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venv/lib/python3.10/site-packages/sympy/categories/__init__.py

@@ -0,0 +1,33 @@
+"""
+Category Theory module.
+
+Provides some of the fundamental category-theory-related classes,
+including categories, morphisms, diagrams.  Functors are not
+implemented yet.
+
+The general reference work this module tries to follow is
+
+  [JoyOfCats] J. Adamek, H. Herrlich. G. E. Strecker: Abstract and
+              Concrete Categories. The Joy of Cats.
+
+The latest version of this book should be available for free download
+from
+
+   katmat.math.uni-bremen.de/acc/acc.pdf
+
+"""
+
+from .baseclasses import (Object, Morphism, IdentityMorphism,
+                         NamedMorphism, CompositeMorphism, Category,
+                         Diagram)
+
+from .diagram_drawing import (DiagramGrid, XypicDiagramDrawer,
+                             xypic_draw_diagram, preview_diagram)
+
+__all__ = [
+    'Object', 'Morphism', 'IdentityMorphism', 'NamedMorphism',
+    'CompositeMorphism', 'Category', 'Diagram',
+
+    'DiagramGrid', 'XypicDiagramDrawer', 'xypic_draw_diagram',
+    'preview_diagram',
+]

venv/lib/python3.10/site-packages/sympy/categories/baseclasses.py

@@ -0,0 +1,979 @@
+from sympy.core import S, Basic, Dict, Symbol, Tuple, sympify
+from sympy.core.symbol import Str
+from sympy.sets import Set, FiniteSet, EmptySet
+from sympy.utilities.iterables import iterable
+
+
+class Class(Set):
+    r"""
+    The base class for any kind of class in the set-theoretic sense.
+
+    Explanation
+    ===========
+
+    In axiomatic set theories, everything is a class.  A class which
+    can be a member of another class is a set.  A class which is not a
+    member of another class is a proper class.  The class `\{1, 2\}`
+    is a set; the class of all sets is a proper class.
+
+    This class is essentially a synonym for :class:`sympy.core.Set`.
+    The goal of this class is to assure easier migration to the
+    eventual proper implementation of set theory.
+    """
+    is_proper = False
+
+
+class Object(Symbol):
+    """
+    The base class for any kind of object in an abstract category.
+
+    Explanation
+    ===========
+
+    While technically any instance of :class:`~.Basic` will do, this
+    class is the recommended way to create abstract objects in
+    abstract categories.
+    """
+
+
+class Morphism(Basic):
+    """
+    The base class for any morphism in an abstract category.
+
+    Explanation
+    ===========
+
+    In abstract categories, a morphism is an arrow between two
+    category objects.  The object where the arrow starts is called the
+    domain, while the object where the arrow ends is called the
+    codomain.
+
+    Two morphisms between the same pair of objects are considered to
+    be the same morphisms.  To distinguish between morphisms between
+    the same objects use :class:`NamedMorphism`.
+
+    It is prohibited to instantiate this class.  Use one of the
+    derived classes instead.
+
+    See Also
+    ========
+
+    IdentityMorphism, NamedMorphism, CompositeMorphism
+    """
+    def __new__(cls, domain, codomain):
+        raise(NotImplementedError(
+            "Cannot instantiate Morphism.  Use derived classes instead."))
+
+    @property
+    def domain(self):
+        """
+        Returns the domain of the morphism.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> f.domain
+        Object("A")
+
+        """
+        return self.args[0]
+
+    @property
+    def codomain(self):
+        """
+        Returns the codomain of the morphism.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> f.codomain
+        Object("B")
+
+        """
+        return self.args[1]
+
+    def compose(self, other):
+        r"""
+        Composes self with the supplied morphism.
+
+        The order of elements in the composition is the usual order,
+        i.e., to construct `g\circ f` use ``g.compose(f)``.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> g * f
+        CompositeMorphism((NamedMorphism(Object("A"), Object("B"), "f"),
+        NamedMorphism(Object("B"), Object("C"), "g")))
+        >>> (g * f).domain
+        Object("A")
+        >>> (g * f).codomain
+        Object("C")
+
+        """
+        return CompositeMorphism(other, self)
+
+    def __mul__(self, other):
+        r"""
+        Composes self with the supplied morphism.
+
+        The semantics of this operation is given by the following
+        equation: ``g * f == g.compose(f)`` for composable morphisms
+        ``g`` and ``f``.
+
+        See Also
+        ========
+
+        compose
+        """
+        return self.compose(other)
+
+
+class IdentityMorphism(Morphism):
+    """
+    Represents an identity morphism.
+
+    Explanation
+    ===========
+
+    An identity morphism is a morphism with equal domain and codomain,
+    which acts as an identity with respect to composition.
+
+    Examples
+    ========
+
+    >>> from sympy.categories import Object, NamedMorphism, IdentityMorphism
+    >>> A = Object("A")
+    >>> B = Object("B")
+    >>> f = NamedMorphism(A, B, "f")
+    >>> id_A = IdentityMorphism(A)
+    >>> id_B = IdentityMorphism(B)
+    >>> f * id_A == f
+    True
+    >>> id_B * f == f
+    True
+
+    See Also
+    ========
+
+    Morphism
+    """
+    def __new__(cls, domain):
+        return Basic.__new__(cls, domain)
+
+    @property
+    def codomain(self):
+        return self.domain
+
+
+class NamedMorphism(Morphism):
+    """
+    Represents a morphism which has a name.
+
+    Explanation
+    ===========
+
+    Names are used to distinguish between morphisms which have the
+    same domain and codomain: two named morphisms are equal if they
+    have the same domains, codomains, and names.
+
+    Examples
+    ========
+
+    >>> from sympy.categories import Object, NamedMorphism
+    >>> A = Object("A")
+    >>> B = Object("B")
+    >>> f = NamedMorphism(A, B, "f")
+    >>> f
+    NamedMorphism(Object("A"), Object("B"), "f")
+    >>> f.name
+    'f'
+
+    See Also
+    ========
+
+    Morphism
+    """
+    def __new__(cls, domain, codomain, name):
+        if not name:
+            raise ValueError("Empty morphism names not allowed.")
+
+        if not isinstance(name, Str):
+            name = Str(name)
+
+        return Basic.__new__(cls, domain, codomain, name)
+
+    @property
+    def name(self):
+        """
+        Returns the name of the morphism.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> f.name
+        'f'
+
+        """
+        return self.args[2].name
+
+
+class CompositeMorphism(Morphism):
+    r"""
+    Represents a morphism which is a composition of other morphisms.
+
+    Explanation
+    ===========
+
+    Two composite morphisms are equal if the morphisms they were
+    obtained from (components) are the same and were listed in the
+    same order.
+
+    The arguments to the constructor for this class should be listed
+    in diagram order: to obtain the composition `g\circ f` from the
+    instances of :class:`Morphism` ``g`` and ``f`` use
+    ``CompositeMorphism(f, g)``.
+
+    Examples
+    ========
+
+    >>> from sympy.categories import Object, NamedMorphism, CompositeMorphism
+    >>> A = Object("A")
+    >>> B = Object("B")
+    >>> C = Object("C")
+    >>> f = NamedMorphism(A, B, "f")
+    >>> g = NamedMorphism(B, C, "g")
+    >>> g * f
+    CompositeMorphism((NamedMorphism(Object("A"), Object("B"), "f"),
+    NamedMorphism(Object("B"), Object("C"), "g")))
+    >>> CompositeMorphism(f, g) == g * f
+    True
+
+    """
+    @staticmethod
+    def _add_morphism(t, morphism):
+        """
+        Intelligently adds ``morphism`` to tuple ``t``.
+
+        Explanation
+        ===========
+
+        If ``morphism`` is a composite morphism, its components are
+        added to the tuple.  If ``morphism`` is an identity, nothing
+        is added to the tuple.
+
+        No composability checks are performed.
+        """
+        if isinstance(morphism, CompositeMorphism):
+            # ``morphism`` is a composite morphism; we have to
+            # denest its components.
+            return t + morphism.components
+        elif isinstance(morphism, IdentityMorphism):
+            # ``morphism`` is an identity.  Nothing happens.
+            return t
+        else:
+            return t + Tuple(morphism)
+
+    def __new__(cls, *components):
+        if components and not isinstance(components[0], Morphism):
+            # Maybe the user has explicitly supplied a list of
+            # morphisms.
+            return CompositeMorphism.__new__(cls, *components[0])
+
+        normalised_components = Tuple()
+
+        for current, following in zip(components, components[1:]):
+            if not isinstance(current, Morphism) or \
+                    not isinstance(following, Morphism):
+                raise TypeError("All components must be morphisms.")
+
+            if current.codomain != following.domain:
+                raise ValueError("Uncomposable morphisms.")
+
+            normalised_components = CompositeMorphism._add_morphism(
+                normalised_components, current)
+
+        # We haven't added the last morphism to the list of normalised
+        # components.  Add it now.
+        normalised_components = CompositeMorphism._add_morphism(
+            normalised_components, components[-1])
+
+        if not normalised_components:
+            # If ``normalised_components`` is empty, only identities
+            # were supplied.  Since they all were composable, they are
+            # all the same identities.
+            return components[0]
+        elif len(normalised_components) == 1:
+            # No sense to construct a whole CompositeMorphism.
+            return normalised_components[0]
+
+        return Basic.__new__(cls, normalised_components)
+
+    @property
+    def components(self):
+        """
+        Returns the components of this composite morphism.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> (g * f).components
+        (NamedMorphism(Object("A"), Object("B"), "f"),
+        NamedMorphism(Object("B"), Object("C"), "g"))
+
+        """
+        return self.args[0]
+
+    @property
+    def domain(self):
+        """
+        Returns the domain of this composite morphism.
+
+        The domain of the composite morphism is the domain of its
+        first component.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> (g * f).domain
+        Object("A")
+
+        """
+        return self.components[0].domain
+
+    @property
+    def codomain(self):
+        """
+        Returns the codomain of this composite morphism.
+
+        The codomain of the composite morphism is the codomain of its
+        last component.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> (g * f).codomain
+        Object("C")
+
+        """
+        return self.components[-1].codomain
+
+    def flatten(self, new_name):
+        """
+        Forgets the composite structure of this morphism.
+
+        Explanation
+        ===========
+
+        If ``new_name`` is not empty, returns a :class:`NamedMorphism`
+        with the supplied name, otherwise returns a :class:`Morphism`.
+        In both cases the domain of the new morphism is the domain of
+        this composite morphism and the codomain of the new morphism
+        is the codomain of this composite morphism.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> (g * f).flatten("h")
+        NamedMorphism(Object("A"), Object("C"), "h")
+
+        """
+        return NamedMorphism(self.domain, self.codomain, new_name)
+
+
+class Category(Basic):
+    r"""
+    An (abstract) category.
+
+    Explanation
+    ===========
+
+    A category [JoyOfCats] is a quadruple `\mbox{K} = (O, \hom, id,
+    \circ)` consisting of
+
+    * a (set-theoretical) class `O`, whose members are called
+      `K`-objects,
+
+    * for each pair `(A, B)` of `K`-objects, a set `\hom(A, B)` whose
+      members are called `K`-morphisms from `A` to `B`,
+
+    * for a each `K`-object `A`, a morphism `id:A\rightarrow A`,
+      called the `K`-identity of `A`,
+
+    * a composition law `\circ` associating with every `K`-morphisms
+      `f:A\rightarrow B` and `g:B\rightarrow C` a `K`-morphism `g\circ
+      f:A\rightarrow C`, called the composite of `f` and `g`.
+
+    Composition is associative, `K`-identities are identities with
+    respect to composition, and the sets `\hom(A, B)` are pairwise
+    disjoint.
+
+    This class knows nothing about its objects and morphisms.
+    Concrete cases of (abstract) categories should be implemented as
+    classes derived from this one.
+
+    Certain instances of :class:`Diagram` can be asserted to be
+    commutative in a :class:`Category` by supplying the argument
+    ``commutative_diagrams`` in the constructor.
+
+    Examples
+    ========
+
+    >>> from sympy.categories import Object, NamedMorphism, Diagram, Category
+    >>> from sympy import FiniteSet
+    >>> A = Object("A")
+    >>> B = Object("B")
+    >>> C = Object("C")
+    >>> f = NamedMorphism(A, B, "f")
+    >>> g = NamedMorphism(B, C, "g")
+    >>> d = Diagram([f, g])
+    >>> K = Category("K", commutative_diagrams=[d])
+    >>> K.commutative_diagrams == FiniteSet(d)
+    True
+
+    See Also
+    ========
+
+    Diagram
+    """
+    def __new__(cls, name, objects=EmptySet, commutative_diagrams=EmptySet):
+        if not name:
+            raise ValueError("A Category cannot have an empty name.")
+
+        if not isinstance(name, Str):
+            name = Str(name)
+
+        if not isinstance(objects, Class):
+            objects = Class(objects)
+
+        new_category = Basic.__new__(cls, name, objects,
+                                     FiniteSet(*commutative_diagrams))
+        return new_category
+
+    @property
+    def name(self):
+        """
+        Returns the name of this category.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Category
+        >>> K = Category("K")
+        >>> K.name
+        'K'
+
+        """
+        return self.args[0].name
+
+    @property
+    def objects(self):
+        """
+        Returns the class of objects of this category.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, Category
+        >>> from sympy import FiniteSet
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> K = Category("K", FiniteSet(A, B))
+        >>> K.objects
+        Class({Object("A"), Object("B")})
+
+        """
+        return self.args[1]
+
+    @property
+    def commutative_diagrams(self):
+        """
+        Returns the :class:`~.FiniteSet` of diagrams which are known to
+        be commutative in this category.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism, Diagram, Category
+        >>> from sympy import FiniteSet
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> d = Diagram([f, g])
+        >>> K = Category("K", commutative_diagrams=[d])
+        >>> K.commutative_diagrams == FiniteSet(d)
+        True
+
+        """
+        return self.args[2]
+
+    def hom(self, A, B):
+        raise NotImplementedError(
+            "hom-sets are not implemented in Category.")
+
+    def all_morphisms(self):
+        raise NotImplementedError(
+            "Obtaining the class of morphisms is not implemented in Category.")
+
+
+class Diagram(Basic):
+    r"""
+    Represents a diagram in a certain category.
+
+    Explanation
+    ===========
+
+    Informally, a diagram is a collection of objects of a category and
+    certain morphisms between them.  A diagram is still a monoid with
+    respect to morphism composition; i.e., identity morphisms, as well
+    as all composites of morphisms included in the diagram belong to
+    the diagram.  For a more formal approach to this notion see
+    [Pare1970].
+
+    The components of composite morphisms are also added to the
+    diagram.  No properties are assigned to such morphisms by default.
+
+    A commutative diagram is often accompanied by a statement of the
+    following kind: "if such morphisms with such properties exist,
+    then such morphisms which such properties exist and the diagram is
+    commutative".  To represent this, an instance of :class:`Diagram`
+    includes a collection of morphisms which are the premises and
+    another collection of conclusions.  ``premises`` and
+    ``conclusions`` associate morphisms belonging to the corresponding
+    categories with the :class:`~.FiniteSet`'s of their properties.
+
+    The set of properties of a composite morphism is the intersection
+    of the sets of properties of its components.  The domain and
+    codomain of a conclusion morphism should be among the domains and
+    codomains of the morphisms listed as the premises of a diagram.
+
+    No checks are carried out of whether the supplied object and
+    morphisms do belong to one and the same category.
+
+    Examples
+    ========
+
+    >>> from sympy.categories import Object, NamedMorphism, Diagram
+    >>> from sympy import pprint, default_sort_key
+    >>> A = Object("A")
+    >>> B = Object("B")
+    >>> C = Object("C")
+    >>> f = NamedMorphism(A, B, "f")
+    >>> g = NamedMorphism(B, C, "g")
+    >>> d = Diagram([f, g])
+    >>> premises_keys = sorted(d.premises.keys(), key=default_sort_key)
+    >>> pprint(premises_keys, use_unicode=False)
+    [g*f:A-->C, id:A-->A, id:B-->B, id:C-->C, f:A-->B, g:B-->C]
+    >>> pprint(d.premises, use_unicode=False)
+    {g*f:A-->C: EmptySet, id:A-->A: EmptySet, id:B-->B: EmptySet, id:C-->C: EmptyS
+    et, f:A-->B: EmptySet, g:B-->C: EmptySet}
+    >>> d = Diagram([f, g], {g * f: "unique"})
+    >>> pprint(d.conclusions,use_unicode=False)
+    {g*f:A-->C: {unique}}
+
+    References
+    ==========
+
+    [Pare1970] B. Pareigis: Categories and functors.  Academic Press, 1970.
+
+    """
+    @staticmethod
+    def _set_dict_union(dictionary, key, value):
+        """
+        If ``key`` is in ``dictionary``, set the new value of ``key``
+        to be the union between the old value and ``value``.
+        Otherwise, set the value of ``key`` to ``value.
+
+        Returns ``True`` if the key already was in the dictionary and
+        ``False`` otherwise.
+        """
+        if key in dictionary:
+            dictionary[key] = dictionary[key] | value
+            return True
+        else:
+            dictionary[key] = value
+            return False
+
+    @staticmethod
+    def _add_morphism_closure(morphisms, morphism, props, add_identities=True,
+                              recurse_composites=True):
+        """
+        Adds a morphism and its attributes to the supplied dictionary
+        ``morphisms``.  If ``add_identities`` is True, also adds the
+        identity morphisms for the domain and the codomain of
+        ``morphism``.
+        """
+        if not Diagram._set_dict_union(morphisms, morphism, props):
+            # We have just added a new morphism.
+
+            if isinstance(morphism, IdentityMorphism):
+                if props:
+                    # Properties for identity morphisms don't really
+                    # make sense, because very much is known about
+                    # identity morphisms already, so much that they
+                    # are trivial.  Having properties for identity
+                    # morphisms would only be confusing.
+                    raise ValueError(
+                        "Instances of IdentityMorphism cannot have properties.")
+                return
+
+            if add_identities:
+                empty = EmptySet
+
+                id_dom = IdentityMorphism(morphism.domain)
+                id_cod = IdentityMorphism(morphism.codomain)
+
+                Diagram._set_dict_union(morphisms, id_dom, empty)
+                Diagram._set_dict_union(morphisms, id_cod, empty)
+
+            for existing_morphism, existing_props in list(morphisms.items()):
+                new_props = existing_props & props
+                if morphism.domain == existing_morphism.codomain:
+                    left = morphism * existing_morphism
+                    Diagram._set_dict_union(morphisms, left, new_props)
+                if morphism.codomain == existing_morphism.domain:
+                    right = existing_morphism * morphism
+                    Diagram._set_dict_union(morphisms, right, new_props)
+
+            if isinstance(morphism, CompositeMorphism) and recurse_composites:
+                # This is a composite morphism, add its components as
+                # well.
+                empty = EmptySet
+                for component in morphism.components:
+                    Diagram._add_morphism_closure(morphisms, component, empty,
+                                                  add_identities)
+
+    def __new__(cls, *args):
+        """
+        Construct a new instance of Diagram.
+
+        Explanation
+        ===========
+
+        If no arguments are supplied, an empty diagram is created.
+
+        If at least an argument is supplied, ``args[0]`` is
+        interpreted as the premises of the diagram.  If ``args[0]`` is
+        a list, it is interpreted as a list of :class:`Morphism`'s, in
+        which each :class:`Morphism` has an empty set of properties.
+        If ``args[0]`` is a Python dictionary or a :class:`Dict`, it
+        is interpreted as a dictionary associating to some
+        :class:`Morphism`'s some properties.
+
+        If at least two arguments are supplied ``args[1]`` is
+        interpreted as the conclusions of the diagram.  The type of
+        ``args[1]`` is interpreted in exactly the same way as the type
+        of ``args[0]``.  If only one argument is supplied, the diagram
+        has no conclusions.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> from sympy.categories import IdentityMorphism, Diagram
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> d = Diagram([f, g])
+        >>> IdentityMorphism(A) in d.premises.keys()
+        True
+        >>> g * f in d.premises.keys()
+        True
+        >>> d = Diagram([f, g], {g * f: "unique"})
+        >>> d.conclusions[g * f]
+        {unique}
+
+        """
+        premises = {}
+        conclusions = {}
+
+        # Here we will keep track of the objects which appear in the
+        # premises.
+        objects = EmptySet
+
+        if len(args) >= 1:
+            # We've got some premises in the arguments.
+            premises_arg = args[0]
+
+            if isinstance(premises_arg, list):
+                # The user has supplied a list of morphisms, none of
+                # which have any attributes.
+                empty = EmptySet
+
+                for morphism in premises_arg:
+                    objects |= FiniteSet(morphism.domain, morphism.codomain)
+                    Diagram._add_morphism_closure(premises, morphism, empty)
+            elif isinstance(premises_arg, (dict, Dict)):
+                # The user has supplied a dictionary of morphisms and
+                # their properties.
+                for morphism, props in premises_arg.items():
+                    objects |= FiniteSet(morphism.domain, morphism.codomain)
+                    Diagram._add_morphism_closure(
+                        premises, morphism, FiniteSet(*props) if iterable(props) else FiniteSet(props))
+
+        if len(args) >= 2:
+            # We also have some conclusions.
+            conclusions_arg = args[1]
+
+            if isinstance(conclusions_arg, list):
+                # The user has supplied a list of morphisms, none of
+                # which have any attributes.
+                empty = EmptySet
+
+                for morphism in conclusions_arg:
+                    # Check that no new objects appear in conclusions.
+                    if ((sympify(objects.contains(morphism.domain)) is S.true) and
+                        (sympify(objects.contains(morphism.codomain)) is S.true)):
+                        # No need to add identities and recurse
+                        # composites this time.
+                        Diagram._add_morphism_closure(
+                            conclusions, morphism, empty, add_identities=False,
+                            recurse_composites=False)
+            elif isinstance(conclusions_arg, dict) or \
+                    isinstance(conclusions_arg, Dict):
+                # The user has supplied a dictionary of morphisms and
+                # their properties.
+                for morphism, props in conclusions_arg.items():
+                    # Check that no new objects appear in conclusions.
+                    if (morphism.domain in objects) and \
+                       (morphism.codomain in objects):
+                        # No need to add identities and recurse
+                        # composites this time.
+                        Diagram._add_morphism_closure(
+                            conclusions, morphism, FiniteSet(*props) if iterable(props) else FiniteSet(props),
+                            add_identities=False, recurse_composites=False)
+
+        return Basic.__new__(cls, Dict(premises), Dict(conclusions), objects)
+
+    @property
+    def premises(self):
+        """
+        Returns the premises of this diagram.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> from sympy.categories import IdentityMorphism, Diagram
+        >>> from sympy import pretty
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> id_A = IdentityMorphism(A)
+        >>> id_B = IdentityMorphism(B)
+        >>> d = Diagram([f])
+        >>> print(pretty(d.premises, use_unicode=False))
+        {id:A-->A: EmptySet, id:B-->B: EmptySet, f:A-->B: EmptySet}
+
+        """
+        return self.args[0]
+
+    @property
+    def conclusions(self):
+        """
+        Returns the conclusions of this diagram.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> from sympy.categories import IdentityMorphism, Diagram
+        >>> from sympy import FiniteSet
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> d = Diagram([f, g])
+        >>> IdentityMorphism(A) in d.premises.keys()
+        True
+        >>> g * f in d.premises.keys()
+        True
+        >>> d = Diagram([f, g], {g * f: "unique"})
+        >>> d.conclusions[g * f] == FiniteSet("unique")
+        True
+
+        """
+        return self.args[1]
+
+    @property
+    def objects(self):
+        """
+        Returns the :class:`~.FiniteSet` of objects that appear in this
+        diagram.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism, Diagram
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> d = Diagram([f, g])
+        >>> d.objects
+        {Object("A"), Object("B"), Object("C")}
+
+        """
+        return self.args[2]
+
+    def hom(self, A, B):
+        """
+        Returns a 2-tuple of sets of morphisms between objects ``A`` and
+        ``B``: one set of morphisms listed as premises, and the other set
+        of morphisms listed as conclusions.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism, Diagram
+        >>> from sympy import pretty
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> d = Diagram([f, g], {g * f: "unique"})
+        >>> print(pretty(d.hom(A, C), use_unicode=False))
+        ({g*f:A-->C}, {g*f:A-->C})
+
+        See Also
+        ========
+        Object, Morphism
+        """
+        premises = EmptySet
+        conclusions = EmptySet
+
+        for morphism in self.premises.keys():
+            if (morphism.domain == A) and (morphism.codomain == B):
+                premises |= FiniteSet(morphism)
+        for morphism in self.conclusions.keys():
+            if (morphism.domain == A) and (morphism.codomain == B):
+                conclusions |= FiniteSet(morphism)
+
+        return (premises, conclusions)
+
+    def is_subdiagram(self, diagram):
+        """
+        Checks whether ``diagram`` is a subdiagram of ``self``.
+        Diagram `D'` is a subdiagram of `D` if all premises
+        (conclusions) of `D'` are contained in the premises
+        (conclusions) of `D`.  The morphisms contained
+        both in `D'` and `D` should have the same properties for `D'`
+        to be a subdiagram of `D`.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism, Diagram
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> d = Diagram([f, g], {g * f: "unique"})
+        >>> d1 = Diagram([f])
+        >>> d.is_subdiagram(d1)
+        True
+        >>> d1.is_subdiagram(d)
+        False
+        """
+        premises = all((m in self.premises) and
+                       (diagram.premises[m] == self.premises[m])
+                       for m in diagram.premises)
+        if not premises:
+            return False
+
+        conclusions = all((m in self.conclusions) and
+                          (diagram.conclusions[m] == self.conclusions[m])
+                          for m in diagram.conclusions)
+
+        # Premises is surely ``True`` here.
+        return conclusions
+
+    def subdiagram_from_objects(self, objects):
+        """
+        If ``objects`` is a subset of the objects of ``self``, returns
+        a diagram which has as premises all those premises of ``self``
+        which have a domains and codomains in ``objects``, likewise
+        for conclusions.  Properties are preserved.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism, Diagram
+        >>> from sympy import FiniteSet
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> d = Diagram([f, g], {f: "unique", g*f: "veryunique"})
+        >>> d1 = d.subdiagram_from_objects(FiniteSet(A, B))
+        >>> d1 == Diagram([f], {f: "unique"})
+        True
+        """
+        if not objects.is_subset(self.objects):
+            raise ValueError(
+                "Supplied objects should all belong to the diagram.")
+
+        new_premises = {}
+        for morphism, props in self.premises.items():
+            if ((sympify(objects.contains(morphism.domain)) is S.true) and
+                (sympify(objects.contains(morphism.codomain)) is S.true)):
+                new_premises[morphism] = props
+
+        new_conclusions = {}
+        for morphism, props in self.conclusions.items():
+            if ((sympify(objects.contains(morphism.domain)) is S.true) and
+                (sympify(objects.contains(morphism.codomain)) is S.true)):
+                new_conclusions[morphism] = props
+
+        return Diagram(new_premises, new_conclusions)

venv/lib/python3.10/site-packages/sympy/categories/diagram_drawing.py

@@ -0,0 +1,2591 @@
+r"""
+This module contains the functionality to arrange the nodes of a
+diagram on an abstract grid, and then to produce a graphical
+representation of the grid.
+
+The currently supported back-ends are Xy-pic [Xypic].
+
+Layout Algorithm
+================
+
+This section provides an overview of the algorithms implemented in
+:class:`DiagramGrid` to lay out diagrams.
+
+The first step of the algorithm is the removal composite and identity
+morphisms which do not have properties in the supplied diagram.  The
+premises and conclusions of the diagram are then merged.
+
+The generic layout algorithm begins with the construction of the
+"skeleton" of the diagram.  The skeleton is an undirected graph which
+has the objects of the diagram as vertices and has an (undirected)
+edge between each pair of objects between which there exist morphisms.
+The direction of the morphisms does not matter at this stage.  The
+skeleton also includes an edge between each pair of vertices `A` and
+`C` such that there exists an object `B` which is connected via
+a morphism to `A`, and via a morphism to `C`.
+
+The skeleton constructed in this way has the property that every
+object is a vertex of a triangle formed by three edges of the
+skeleton.  This property lies at the base of the generic layout
+algorithm.
+
+After the skeleton has been constructed, the algorithm lists all
+triangles which can be formed.  Note that some triangles will not have
+all edges corresponding to morphisms which will actually be drawn.
+Triangles which have only one edge or less which will actually be
+drawn are immediately discarded.
+
+The list of triangles is sorted according to the number of edges which
+correspond to morphisms, then the triangle with the least number of such
+edges is selected.  One of such edges is picked and the corresponding
+objects are placed horizontally, on a grid.  This edge is recorded to
+be in the fringe.  The algorithm then finds a "welding" of a triangle
+to the fringe.  A welding is an edge in the fringe where a triangle
+could be attached.  If the algorithm succeeds in finding such a
+welding, it adds to the grid that vertex of the triangle which was not
+yet included in any edge in the fringe and records the two new edges in
+the fringe.  This process continues iteratively until all objects of
+the diagram has been placed or until no more weldings can be found.
+
+An edge is only removed from the fringe when a welding to this edge
+has been found, and there is no room around this edge to place
+another vertex.
+
+When no more weldings can be found, but there are still triangles
+left, the algorithm searches for a possibility of attaching one of the
+remaining triangles to the existing structure by a vertex.  If such a
+possibility is found, the corresponding edge of the found triangle is
+placed in the found space and the iterative process of welding
+triangles restarts.
+
+When logical groups are supplied, each of these groups is laid out
+independently.  Then a diagram is constructed in which groups are
+objects and any two logical groups between which there exist morphisms
+are connected via a morphism.  This diagram is laid out.  Finally,
+the grid which includes all objects of the initial diagram is
+constructed by replacing the cells which contain logical groups with
+the corresponding laid out grids, and by correspondingly expanding the
+rows and columns.
+
+The sequential layout algorithm begins by constructing the
+underlying undirected graph defined by the morphisms obtained after
+simplifying premises and conclusions and merging them (see above).
+The vertex with the minimal degree is then picked up and depth-first
+search is started from it.  All objects which are located at distance
+`n` from the root in the depth-first search tree, are positioned in
+the `n`-th column of the resulting grid.  The sequential layout will
+therefore attempt to lay the objects out along a line.
+
+References
+==========
+
+.. [Xypic] https://xy-pic.sourceforge.net/
+
+"""
+from sympy.categories import (CompositeMorphism, IdentityMorphism,
+                              NamedMorphism, Diagram)
+from sympy.core import Dict, Symbol, default_sort_key
+from sympy.printing.latex import latex
+from sympy.sets import FiniteSet
+from sympy.utilities.iterables import iterable
+from sympy.utilities.decorator import doctest_depends_on
+
+from itertools import chain
+
+
+__doctest_requires__ = {('preview_diagram',): 'pyglet'}
+
+
+class _GrowableGrid:
+    """
+    Holds a growable grid of objects.
+
+    Explanation
+    ===========
+
+    It is possible to append or prepend a row or a column to the grid
+    using the corresponding methods.  Prepending rows or columns has
+    the effect of changing the coordinates of the already existing
+    elements.
+
+    This class currently represents a naive implementation of the
+    functionality with little attempt at optimisation.
+    """
+    def __init__(self, width, height):
+        self._width = width
+        self._height = height
+
+        self._array = [[None for j in range(width)] for i in range(height)]
+
+    @property
+    def width(self):
+        return self._width
+
+    @property
+    def height(self):
+        return self._height
+
+    def __getitem__(self, i_j):
+        """
+        Returns the element located at in the i-th line and j-th
+        column.
+        """
+        i, j = i_j
+        return self._array[i][j]
+
+    def __setitem__(self, i_j, newvalue):
+        """
+        Sets the element located at in the i-th line and j-th
+        column.
+        """
+        i, j = i_j
+        self._array[i][j] = newvalue
+
+    def append_row(self):
+        """
+        Appends an empty row to the grid.
+        """
+        self._height += 1
+        self._array.append([None for j in range(self._width)])
+
+    def append_column(self):
+        """
+        Appends an empty column to the grid.
+        """
+        self._width += 1
+        for i in range(self._height):
+            self._array[i].append(None)
+
+    def prepend_row(self):
+        """
+        Prepends the grid with an empty row.
+        """
+        self._height += 1
+        self._array.insert(0, [None for j in range(self._width)])
+
+    def prepend_column(self):
+        """
+        Prepends the grid with an empty column.
+        """
+        self._width += 1
+        for i in range(self._height):
+            self._array[i].insert(0, None)
+
+
+class DiagramGrid:
+    r"""
+    Constructs and holds the fitting of the diagram into a grid.
+
+    Explanation
+    ===========
+
+    The mission of this class is to analyse the structure of the
+    supplied diagram and to place its objects on a grid such that,
+    when the objects and the morphisms are actually drawn, the diagram
+    would be "readable", in the sense that there will not be many
+    intersections of moprhisms.  This class does not perform any
+    actual drawing.  It does strive nevertheless to offer sufficient
+    metadata to draw a diagram.
+
+    Consider the following simple diagram.
+
+    >>> from sympy.categories import Object, NamedMorphism
+    >>> from sympy.categories import Diagram, DiagramGrid
+    >>> from sympy import pprint
+    >>> A = Object("A")
+    >>> B = Object("B")
+    >>> C = Object("C")
+    >>> f = NamedMorphism(A, B, "f")
+    >>> g = NamedMorphism(B, C, "g")
+    >>> diagram = Diagram([f, g])
+
+    The simplest way to have a diagram laid out is the following:
+
+    >>> grid = DiagramGrid(diagram)
+    >>> (grid.width, grid.height)
+    (2, 2)
+    >>> pprint(grid)
+    A  B
+    <BLANKLINE>
+       C
+
+    Sometimes one sees the diagram as consisting of logical groups.
+    One can advise ``DiagramGrid`` as to such groups by employing the
+    ``groups`` keyword argument.
+
+    Consider the following diagram:
+
+    >>> D = Object("D")
+    >>> f = NamedMorphism(A, B, "f")
+    >>> g = NamedMorphism(B, C, "g")
+    >>> h = NamedMorphism(D, A, "h")
+    >>> k = NamedMorphism(D, B, "k")
+    >>> diagram = Diagram([f, g, h, k])
+
+    Lay it out with generic layout:
+
+    >>> grid = DiagramGrid(diagram)
+    >>> pprint(grid)
+    A  B  D
+    <BLANKLINE>
+       C
+
+    Now, we can group the objects `A` and `D` to have them near one
+    another:
+
+    >>> grid = DiagramGrid(diagram, groups=[[A, D], B, C])
+    >>> pprint(grid)
+    B     C
+    <BLANKLINE>
+    A  D
+
+    Note how the positioning of the other objects changes.
+
+    Further indications can be supplied to the constructor of
+    :class:`DiagramGrid` using keyword arguments.  The currently
+    supported hints are explained in the following paragraphs.
+
+    :class:`DiagramGrid` does not automatically guess which layout
+    would suit the supplied diagram better.  Consider, for example,
+    the following linear diagram:
+
+    >>> E = Object("E")
+    >>> f = NamedMorphism(A, B, "f")
+    >>> g = NamedMorphism(B, C, "g")
+    >>> h = NamedMorphism(C, D, "h")
+    >>> i = NamedMorphism(D, E, "i")
+    >>> diagram = Diagram([f, g, h, i])
+
+    When laid out with the generic layout, it does not get to look
+    linear:
+
+    >>> grid = DiagramGrid(diagram)
+    >>> pprint(grid)
+    A  B
+    <BLANKLINE>
+       C  D
+    <BLANKLINE>
+          E
+
+    To get it laid out in a line, use ``layout="sequential"``:
+
+    >>> grid = DiagramGrid(diagram, layout="sequential")
+    >>> pprint(grid)
+    A  B  C  D  E
+
+    One may sometimes need to transpose the resulting layout.  While
+    this can always be done by hand, :class:`DiagramGrid` provides a
+    hint for that purpose:
+
+    >>> grid = DiagramGrid(diagram, layout="sequential", transpose=True)
+    >>> pprint(grid)
+    A
+    <BLANKLINE>
+    B
+    <BLANKLINE>
+    C
+    <BLANKLINE>
+    D
+    <BLANKLINE>
+    E
+
+    Separate hints can also be provided for each group.  For an
+    example, refer to ``tests/test_drawing.py``, and see the different
+    ways in which the five lemma [FiveLemma] can be laid out.
+
+    See Also
+    ========
+
+    Diagram
+
+    References
+    ==========
+
+    .. [FiveLemma] https://en.wikipedia.org/wiki/Five_lemma
+    """
+    @staticmethod
+    def _simplify_morphisms(morphisms):
+        """
+        Given a dictionary mapping morphisms to their properties,
+        returns a new dictionary in which there are no morphisms which
+        do not have properties, and which are compositions of other
+        morphisms included in the dictionary.  Identities are dropped
+        as well.
+        """
+        newmorphisms = {}
+        for morphism, props in morphisms.items():
+            if isinstance(morphism, CompositeMorphism) and not props:
+                continue
+            elif isinstance(morphism, IdentityMorphism):
+                continue
+            else:
+                newmorphisms[morphism] = props
+        return newmorphisms
+
+    @staticmethod
+    def _merge_premises_conclusions(premises, conclusions):
+        """
+        Given two dictionaries of morphisms and their properties,
+        produces a single dictionary which includes elements from both
+        dictionaries.  If a morphism has some properties in premises
+        and also in conclusions, the properties in conclusions take
+        priority.
+        """
+        return dict(chain(premises.items(), conclusions.items()))
+
+    @staticmethod
+    def _juxtapose_edges(edge1, edge2):
+        """
+        If ``edge1`` and ``edge2`` have precisely one common endpoint,
+        returns an edge which would form a triangle with ``edge1`` and
+        ``edge2``.
+
+        If ``edge1`` and ``edge2`` do not have a common endpoint,
+        returns ``None``.
+
+        If ``edge1`` and ``edge`` are the same edge, returns ``None``.
+        """
+        intersection = edge1 & edge2
+        if len(intersection) != 1:
+            # The edges either have no common points or are equal.
+            return None
+
+        # The edges have a common endpoint.  Extract the different
+        # endpoints and set up the new edge.
+        return (edge1 - intersection) | (edge2 - intersection)
+
+    @staticmethod
+    def _add_edge_append(dictionary, edge, elem):
+        """
+        If ``edge`` is not in ``dictionary``, adds ``edge`` to the
+        dictionary and sets its value to ``[elem]``.  Otherwise
+        appends ``elem`` to the value of existing entry.
+
+        Note that edges are undirected, thus `(A, B) = (B, A)`.
+        """
+        if edge in dictionary:
+            dictionary[edge].append(elem)
+        else:
+            dictionary[edge] = [elem]
+
+    @staticmethod
+    def _build_skeleton(morphisms):
+        """
+        Creates a dictionary which maps edges to corresponding
+        morphisms.  Thus for a morphism `f:A\rightarrow B`, the edge
+        `(A, B)` will be associated with `f`.  This function also adds
+        to the list those edges which are formed by juxtaposition of
+        two edges already in the list.  These new edges are not
+        associated with any morphism and are only added to assure that
+        the diagram can be decomposed into triangles.
+        """
+        edges = {}
+        # Create edges for morphisms.
+        for morphism in morphisms:
+            DiagramGrid._add_edge_append(
+                edges, frozenset([morphism.domain, morphism.codomain]), morphism)
+
+        # Create new edges by juxtaposing existing edges.
+        edges1 = dict(edges)
+        for w in edges1:
+            for v in edges1:
+                wv = DiagramGrid._juxtapose_edges(w, v)
+                if wv and wv not in edges:
+                    edges[wv] = []
+
+        return edges
+
+    @staticmethod
+    def _list_triangles(edges):
+        """
+        Builds the set of triangles formed by the supplied edges.  The
+        triangles are arbitrary and need not be commutative.  A
+        triangle is a set that contains all three of its sides.
+        """
+        triangles = set()
+
+        for w in edges:
+            for v in edges:
+                wv = DiagramGrid._juxtapose_edges(w, v)
+                if wv and wv in edges:
+                    triangles.add(frozenset([w, v, wv]))
+
+        return triangles
+
+    @staticmethod
+    def _drop_redundant_triangles(triangles, skeleton):
+        """
+        Returns a list which contains only those triangles who have
+        morphisms associated with at least two edges.
+        """
+        return [tri for tri in triangles
+                if len([e for e in tri if skeleton[e]]) >= 2]
+
+    @staticmethod
+    def _morphism_length(morphism):
+        """
+        Returns the length of a morphism.  The length of a morphism is
+        the number of components it consists of.  A non-composite
+        morphism is of length 1.
+        """
+        if isinstance(morphism, CompositeMorphism):
+            return len(morphism.components)
+        else:
+            return 1
+
+    @staticmethod
+    def _compute_triangle_min_sizes(triangles, edges):
+        r"""
+        Returns a dictionary mapping triangles to their minimal sizes.
+        The minimal size of a triangle is the sum of maximal lengths
+        of morphisms associated to the sides of the triangle.  The
+        length of a morphism is the number of components it consists
+        of.  A non-composite morphism is of length 1.
+
+        Sorting triangles by this metric attempts to address two
+        aspects of layout.  For triangles with only simple morphisms
+        in the edge, this assures that triangles with all three edges
+        visible will get typeset after triangles with less visible
+        edges, which sometimes minimizes the necessity in diagonal
+        arrows.  For triangles with composite morphisms in the edges,
+        this assures that objects connected with shorter morphisms
+        will be laid out first, resulting the visual proximity of
+        those objects which are connected by shorter morphisms.
+        """
+        triangle_sizes = {}
+        for triangle in triangles:
+            size = 0
+            for e in triangle:
+                morphisms = edges[e]
+                if morphisms:
+                    size += max(DiagramGrid._morphism_length(m)
+                                for m in morphisms)
+            triangle_sizes[triangle] = size
+        return triangle_sizes
+
+    @staticmethod
+    def _triangle_objects(triangle):
+        """
+        Given a triangle, returns the objects included in it.
+        """
+        # A triangle is a frozenset of three two-element frozensets
+        # (the edges).  This chains the three edges together and
+        # creates a frozenset from the iterator, thus producing a
+        # frozenset of objects of the triangle.
+        return frozenset(chain(*tuple(triangle)))
+
+    @staticmethod
+    def _other_vertex(triangle, edge):
+        """
+        Given a triangle and an edge of it, returns the vertex which
+        opposes the edge.
+        """
+        # This gets the set of objects of the triangle and then
+        # subtracts the set of objects employed in ``edge`` to get the
+        # vertex opposite to ``edge``.
+        return list(DiagramGrid._triangle_objects(triangle) - set(edge))[0]
+
+    @staticmethod
+    def _empty_point(pt, grid):
+        """
+        Checks if the cell at coordinates ``pt`` is either empty or
+        out of the bounds of the grid.
+        """
+        if (pt[0] < 0) or (pt[1] < 0) or \
+           (pt[0] >= grid.height) or (pt[1] >= grid.width):
+            return True
+        return grid[pt] is None
+
+    @staticmethod
+    def _put_object(coords, obj, grid, fringe):
+        """
+        Places an object at the coordinate ``cords`` in ``grid``,
+        growing the grid and updating ``fringe``, if necessary.
+        Returns (0, 0) if no row or column has been prepended, (1, 0)
+        if a row was prepended, (0, 1) if a column was prepended and
+        (1, 1) if both a column and a row were prepended.
+        """
+        (i, j) = coords
+        offset = (0, 0)
+        if i == -1:
+            grid.prepend_row()
+            i = 0
+            offset = (1, 0)
+            for k in range(len(fringe)):
+                ((i1, j1), (i2, j2)) = fringe[k]
+                fringe[k] = ((i1 + 1, j1), (i2 + 1, j2))
+        elif i == grid.height:
+            grid.append_row()
+
+        if j == -1:
+            j = 0
+            offset = (offset[0], 1)
+            grid.prepend_column()
+            for k in range(len(fringe)):
+                ((i1, j1), (i2, j2)) = fringe[k]
+                fringe[k] = ((i1, j1 + 1), (i2, j2 + 1))
+        elif j == grid.width:
+            grid.append_column()
+
+        grid[i, j] = obj
+        return offset
+
+    @staticmethod
+    def _choose_target_cell(pt1, pt2, edge, obj, skeleton, grid):
+        """
+        Given two points, ``pt1`` and ``pt2``, and the welding edge
+        ``edge``, chooses one of the two points to place the opposing
+        vertex ``obj`` of the triangle.  If neither of this points
+        fits, returns ``None``.
+        """
+        pt1_empty = DiagramGrid._empty_point(pt1, grid)
+        pt2_empty = DiagramGrid._empty_point(pt2, grid)
+
+        if pt1_empty and pt2_empty:
+            # Both cells are empty.  Of these two, choose that cell
+            # which will assure that a visible edge of the triangle
+            # will be drawn perpendicularly to the current welding
+            # edge.
+
+            A = grid[edge[0]]
+
+            if skeleton.get(frozenset([A, obj])):
+                return pt1
+            else:
+                return pt2
+        if pt1_empty:
+            return pt1
+        elif pt2_empty:
+            return pt2
+        else:
+            return None
+
+    @staticmethod
+    def _find_triangle_to_weld(triangles, fringe, grid):
+        """
+        Finds, if possible, a triangle and an edge in the ``fringe`` to
+        which the triangle could be attached.  Returns the tuple
+        containing the triangle and the index of the corresponding
+        edge in the ``fringe``.
+
+        This function relies on the fact that objects are unique in
+        the diagram.
+        """
+        for triangle in triangles:
+            for (a, b) in fringe:
+                if frozenset([grid[a], grid[b]]) in triangle:
+                    return (triangle, (a, b))
+        return None
+
+    @staticmethod
+    def _weld_triangle(tri, welding_edge, fringe, grid, skeleton):
+        """
+        If possible, welds the triangle ``tri`` to ``fringe`` and
+        returns ``False``.  If this method encounters a degenerate
+        situation in the fringe and corrects it such that a restart of
+        the search is required, it returns ``True`` (which means that
+        a restart in finding triangle weldings is required).
+
+        A degenerate situation is a situation when an edge listed in
+        the fringe does not belong to the visual boundary of the
+        diagram.
+        """
+        a, b = welding_edge
+        target_cell = None
+
+        obj = DiagramGrid._other_vertex(tri, (grid[a], grid[b]))
+
+        # We now have a triangle and an edge where it can be welded to
+        # the fringe.  Decide where to place the other vertex of the
+        # triangle and check for degenerate situations en route.
+
+        if (abs(a[0] - b[0]) == 1) and (abs(a[1] - b[1]) == 1):
+            # A diagonal edge.
+            target_cell = (a[0], b[1])
+            if grid[target_cell]:
+                # That cell is already occupied.
+                target_cell = (b[0], a[1])
+
+                if grid[target_cell]:
+                    # Degenerate situation, this edge is not
+                    # on the actual fringe.  Correct the
+                    # fringe and go on.
+                    fringe.remove((a, b))
+                    return True
+        elif a[0] == b[0]:
+            # A horizontal edge.  We first attempt to build the
+            # triangle in the downward direction.
+
+            down_left = a[0] + 1, a[1]
+            down_right = a[0] + 1, b[1]
+
+            target_cell = DiagramGrid._choose_target_cell(
+                down_left, down_right, (a, b), obj, skeleton, grid)
+
+            if not target_cell:
+                # No room below this edge.  Check above.
+                up_left = a[0] - 1, a[1]
+                up_right = a[0] - 1, b[1]
+
+                target_cell = DiagramGrid._choose_target_cell(
+                    up_left, up_right, (a, b), obj, skeleton, grid)
+
+                if not target_cell:
+                    # This edge is not in the fringe, remove it
+                    # and restart.
+                    fringe.remove((a, b))
+                    return True
+        elif a[1] == b[1]:
+            # A vertical edge.  We will attempt to place the other
+            # vertex of the triangle to the right of this edge.
+            right_up = a[0], a[1] + 1
+            right_down = b[0], a[1] + 1
+
+            target_cell = DiagramGrid._choose_target_cell(
+                right_up, right_down, (a, b), obj, skeleton, grid)
+
+            if not target_cell:
+                # No room to the left.  See what's to the right.
+                left_up = a[0], a[1] - 1
+                left_down = b[0], a[1] - 1
+
+                target_cell = DiagramGrid._choose_target_cell(
+                    left_up, left_down, (a, b), obj, skeleton, grid)
+
+                if not target_cell:
+                    # This edge is not in the fringe, remove it
+                    # and restart.
+                    fringe.remove((a, b))
+                    return True
+
+        # We now know where to place the other vertex of the
+        # triangle.
+        offset = DiagramGrid._put_object(target_cell, obj, grid, fringe)
+
+        # Take care of the displacement of coordinates if a row or
+        # a column was prepended.
+        target_cell = (target_cell[0] + offset[0],
+                       target_cell[1] + offset[1])
+        a = (a[0] + offset[0], a[1] + offset[1])
+        b = (b[0] + offset[0], b[1] + offset[1])
+
+        fringe.extend([(a, target_cell), (b, target_cell)])
+
+        # No restart is required.
+        return False
+
+    @staticmethod
+    def _triangle_key(tri, triangle_sizes):
+        """
+        Returns a key for the supplied triangle.  It should be the
+        same independently of the hash randomisation.
+        """
+        objects = sorted(
+            DiagramGrid._triangle_objects(tri), key=default_sort_key)
+        return (triangle_sizes[tri], default_sort_key(objects))
+
+    @staticmethod
+    def _pick_root_edge(tri, skeleton):
+        """
+        For a given triangle always picks the same root edge.  The
+        root edge is the edge that will be placed first on the grid.
+        """
+        candidates = [sorted(e, key=default_sort_key)
+                      for e in tri if skeleton[e]]
+        sorted_candidates = sorted(candidates, key=default_sort_key)
+        # Don't forget to assure the proper ordering of the vertices
+        # in this edge.
+        return tuple(sorted(sorted_candidates[0], key=default_sort_key))
+
+    @staticmethod
+    def _drop_irrelevant_triangles(triangles, placed_objects):
+        """
+        Returns only those triangles whose set of objects is not
+        completely included in ``placed_objects``.
+        """
+        return [tri for tri in triangles if not placed_objects.issuperset(
+            DiagramGrid._triangle_objects(tri))]
+
+    @staticmethod
+    def _grow_pseudopod(triangles, fringe, grid, skeleton, placed_objects):
+        """
+        Starting from an object in the existing structure on the ``grid``,
+        adds an edge to which a triangle from ``triangles`` could be
+        welded.  If this method has found a way to do so, it returns
+        the object it has just added.
+
+        This method should be applied when ``_weld_triangle`` cannot
+        find weldings any more.
+        """
+        for i in range(grid.height):
+            for j in range(grid.width):
+                obj = grid[i, j]
+                if not obj:
+                    continue
+
+                # Here we need to choose a triangle which has only
+                # ``obj`` in common with the existing structure.  The
+                # situations when this is not possible should be
+                # handled elsewhere.
+
+                def good_triangle(tri):
+                    objs = DiagramGrid._triangle_objects(tri)
+                    return obj in objs and \
+                        placed_objects & (objs - {obj}) == set()
+
+                tris = [tri for tri in triangles if good_triangle(tri)]
+                if not tris:
+                    # This object is not interesting.
+                    continue
+
+                # Pick the "simplest" of the triangles which could be
+                # attached.  Remember that the list of triangles is
+                # sorted according to their "simplicity" (see
+                # _compute_triangle_min_sizes for the metric).
+                #
+                # Note that ``tris`` are sequentially built from
+                # ``triangles``, so we don't have to worry about hash
+                # randomisation.
+                tri = tris[0]
+
+                # We have found a triangle which could be attached to
+                # the existing structure by a vertex.
+
+                candidates = sorted([e for e in tri if skeleton[e]],
+                                    key=lambda e: FiniteSet(*e).sort_key())
+                edges = [e for e in candidates if obj in e]
+
+                # Note that a meaningful edge (i.e., and edge that is
+                # associated with a morphism) containing ``obj``
+                # always exists.  That's because all triangles are
+                # guaranteed to have at least two meaningful edges.
+                # See _drop_redundant_triangles.
+
+                # Get the object at the other end of the edge.
+                edge = edges[0]
+                other_obj = tuple(edge - frozenset([obj]))[0]
+
+                # Now check for free directions.  When checking for
+                # free directions, prefer the horizontal and vertical
+                # directions.
+                neighbours = [(i - 1, j), (i, j + 1), (i + 1, j), (i, j - 1),
+                              (i - 1, j - 1), (i - 1, j + 1), (i + 1, j - 1), (i + 1, j + 1)]
+
+                for pt in neighbours:
+                    if DiagramGrid._empty_point(pt, grid):
+                        # We have a found a place to grow the
+                        # pseudopod into.
+                        offset = DiagramGrid._put_object(
+                            pt, other_obj, grid, fringe)
+
+                        i += offset[0]
+                        j += offset[1]
+                        pt = (pt[0] + offset[0], pt[1] + offset[1])
+                        fringe.append(((i, j), pt))
+
+                        return other_obj
+
+        # This diagram is actually cooler that I can handle.  Fail cowardly.
+        return None
+
+    @staticmethod
+    def _handle_groups(diagram, groups, merged_morphisms, hints):
+        """
+        Given the slightly preprocessed morphisms of the diagram,
+        produces a grid laid out according to ``groups``.
+
+        If a group has hints, it is laid out with those hints only,
+        without any influence from ``hints``.  Otherwise, it is laid
+        out with ``hints``.
+        """
+        def lay_out_group(group, local_hints):
+            """
+            If ``group`` is a set of objects, uses a ``DiagramGrid``
+            to lay it out and returns the grid.  Otherwise returns the
+            object (i.e., ``group``).  If ``local_hints`` is not
+            empty, it is supplied to ``DiagramGrid`` as the dictionary
+            of hints.  Otherwise, the ``hints`` argument of
+            ``_handle_groups`` is used.
+            """
+            if isinstance(group, FiniteSet):
+                # Set up the corresponding object-to-group
+                # mappings.
+                for obj in group:
+                    obj_groups[obj] = group
+
+                # Lay out the current group.
+                if local_hints:
+                    groups_grids[group] = DiagramGrid(
+                        diagram.subdiagram_from_objects(group), **local_hints)
+                else:
+                    groups_grids[group] = DiagramGrid(
+                        diagram.subdiagram_from_objects(group), **hints)
+            else:
+                obj_groups[group] = group
+
+        def group_to_finiteset(group):
+            """
+            Converts ``group`` to a :class:``FiniteSet`` if it is an
+            iterable.
+            """
+            if iterable(group):
+                return FiniteSet(*group)
+            else:
+                return group
+
+        obj_groups = {}
+        groups_grids = {}
+
+        # We would like to support various containers to represent
+        # groups.  To achieve that, before laying each group out, it
+        # should be converted to a FiniteSet, because that is what the
+        # following code expects.
+
+        if isinstance(groups, (dict, Dict)):
+            finiteset_groups = {}
+            for group, local_hints in groups.items():
+                finiteset_group = group_to_finiteset(group)
+                finiteset_groups[finiteset_group] = local_hints
+                lay_out_group(group, local_hints)
+            groups = finiteset_groups
+        else:
+            finiteset_groups = []
+            for group in groups:
+                finiteset_group = group_to_finiteset(group)
+                finiteset_groups.append(finiteset_group)
+                lay_out_group(finiteset_group, None)
+            groups = finiteset_groups
+
+        new_morphisms = []
+        for morphism in merged_morphisms:
+            dom = obj_groups[morphism.domain]
+            cod = obj_groups[morphism.codomain]
+            # Note that we are not really interested in morphisms
+            # which do not employ two different groups, because
+            # these do not influence the layout.
+            if dom != cod:
+                # These are essentially unnamed morphisms; they are
+                # not going to mess in the final layout.  By giving
+                # them the same names, we avoid unnecessary
+                # duplicates.
+                new_morphisms.append(NamedMorphism(dom, cod, "dummy"))
+
+        # Lay out the new diagram.  Since these are dummy morphisms,
+        # properties and conclusions are irrelevant.
+        top_grid = DiagramGrid(Diagram(new_morphisms))
+
+        # We now have to substitute the groups with the corresponding
+        # grids, laid out at the beginning of this function.  Compute
+        # the size of each row and column in the grid, so that all
+        # nested grids fit.
+
+        def group_size(group):
+            """
+            For the supplied group (or object, eventually), returns
+            the size of the cell that will hold this group (object).
+            """
+            if group in groups_grids:
+                grid = groups_grids[group]
+                return (grid.height, grid.width)
+            else:
+                return (1, 1)
+
+        row_heights = [max(group_size(top_grid[i, j])[0]
+                           for j in range(top_grid.width))
+                       for i in range(top_grid.height)]
+
+        column_widths = [max(group_size(top_grid[i, j])[1]
+                             for i in range(top_grid.height))
+                         for j in range(top_grid.width)]
+
+        grid = _GrowableGrid(sum(column_widths), sum(row_heights))
+
+        real_row = 0
+        real_column = 0
+        for logical_row in range(top_grid.height):
+            for logical_column in range(top_grid.width):
+                obj = top_grid[logical_row, logical_column]
+
+                if obj in groups_grids:
+                    # This is a group.  Copy the corresponding grid in
+                    # place.
+                    local_grid = groups_grids[obj]
+                    for i in range(local_grid.height):
+                        for j in range(local_grid.width):
+                            grid[real_row + i,
+                                real_column + j] = local_grid[i, j]
+                else:
+                    # This is an object.  Just put it there.
+                    grid[real_row, real_column] = obj
+
+                real_column += column_widths[logical_column]
+            real_column = 0
+            real_row += row_heights[logical_row]
+
+        return grid
+
+    @staticmethod
+    def _generic_layout(diagram, merged_morphisms):
+        """
+        Produces the generic layout for the supplied diagram.
+        """
+        all_objects = set(diagram.objects)
+        if len(all_objects) == 1:
+            # There only one object in the diagram, just put in on 1x1
+            # grid.
+            grid = _GrowableGrid(1, 1)
+            grid[0, 0] = tuple(all_objects)[0]
+            return grid
+
+        skeleton = DiagramGrid._build_skeleton(merged_morphisms)
+
+        grid = _GrowableGrid(2, 1)
+
+        if len(skeleton) == 1:
+            # This diagram contains only one morphism.  Draw it
+            # horizontally.
+            objects = sorted(all_objects, key=default_sort_key)
+            grid[0, 0] = objects[0]
+            grid[0, 1] = objects[1]
+
+            return grid
+
+        triangles = DiagramGrid._list_triangles(skeleton)
+        triangles = DiagramGrid._drop_redundant_triangles(triangles, skeleton)
+        triangle_sizes = DiagramGrid._compute_triangle_min_sizes(
+            triangles, skeleton)
+
+        triangles = sorted(triangles, key=lambda tri:
+                           DiagramGrid._triangle_key(tri, triangle_sizes))
+
+        # Place the first edge on the grid.
+        root_edge = DiagramGrid._pick_root_edge(triangles[0], skeleton)
+        grid[0, 0], grid[0, 1] = root_edge
+        fringe = [((0, 0), (0, 1))]
+
+        # Record which objects we now have on the grid.
+        placed_objects = set(root_edge)
+
+        while placed_objects != all_objects:
+            welding = DiagramGrid._find_triangle_to_weld(
+                triangles, fringe, grid)
+
+            if welding:
+                (triangle, welding_edge) = welding
+
+                restart_required = DiagramGrid._weld_triangle(
+                    triangle, welding_edge, fringe, grid, skeleton)
+                if restart_required:
+                    continue
+
+                placed_objects.update(
+                    DiagramGrid._triangle_objects(triangle))
+            else:
+                # No more weldings found.  Try to attach triangles by
+                # vertices.
+                new_obj = DiagramGrid._grow_pseudopod(
+                    triangles, fringe, grid, skeleton, placed_objects)
+
+                if not new_obj:
+                    # No more triangles can be attached, not even by
+                    # the edge.  We will set up a new diagram out of
+                    # what has been left, laid it out independently,
+                    # and then attach it to this one.
+
+                    remaining_objects = all_objects - placed_objects
+
+                    remaining_diagram = diagram.subdiagram_from_objects(
+                        FiniteSet(*remaining_objects))
+                    remaining_grid = DiagramGrid(remaining_diagram)
+
+                    # Now, let's glue ``remaining_grid`` to ``grid``.
+                    final_width = grid.width + remaining_grid.width
+                    final_height = max(grid.height, remaining_grid.height)
+                    final_grid = _GrowableGrid(final_width, final_height)
+
+                    for i in range(grid.width):
+                        for j in range(grid.height):
+                            final_grid[i, j] = grid[i, j]
+
+                    start_j = grid.width
+                    for i in range(remaining_grid.height):
+                        for j in range(remaining_grid.width):
+                            final_grid[i, start_j + j] = remaining_grid[i, j]
+
+                    return final_grid
+
+                placed_objects.add(new_obj)
+
+            triangles = DiagramGrid._drop_irrelevant_triangles(
+                triangles, placed_objects)
+
+        return grid
+
+    @staticmethod
+    def _get_undirected_graph(objects, merged_morphisms):
+        """
+        Given the objects and the relevant morphisms of a diagram,
+        returns the adjacency lists of the underlying undirected
+        graph.
+        """
+        adjlists = {}
+        for obj in objects:
+            adjlists[obj] = []
+
+        for morphism in merged_morphisms:
+            adjlists[morphism.domain].append(morphism.codomain)
+            adjlists[morphism.codomain].append(morphism.domain)
+
+        # Assure that the objects in the adjacency list are always in
+        # the same order.
+        for obj in adjlists.keys():
+            adjlists[obj].sort(key=default_sort_key)
+
+        return adjlists
+
+    @staticmethod
+    def _sequential_layout(diagram, merged_morphisms):
+        r"""
+        Lays out the diagram in "sequential" layout.  This method
+        will attempt to produce a result as close to a line as
+        possible.  For linear diagrams, the result will actually be a
+        line.
+        """
+        objects = diagram.objects
+        sorted_objects = sorted(objects, key=default_sort_key)
+
+        # Set up the adjacency lists of the underlying undirected
+        # graph of ``merged_morphisms``.
+        adjlists = DiagramGrid._get_undirected_graph(objects, merged_morphisms)
+
+        # Find an object with the minimal degree.  This is going to be
+        # the root.
+        root = sorted_objects[0]
+        mindegree = len(adjlists[root])
+        for obj in sorted_objects:
+            current_degree = len(adjlists[obj])
+            if current_degree < mindegree:
+                root = obj
+                mindegree = current_degree
+
+        grid = _GrowableGrid(1, 1)
+        grid[0, 0] = root
+
+        placed_objects = {root}
+
+        def place_objects(pt, placed_objects):
+            """
+            Does depth-first search in the underlying graph of the
+            diagram and places the objects en route.
+            """
+            # We will start placing new objects from here.
+            new_pt = (pt[0], pt[1] + 1)
+
+            for adjacent_obj in adjlists[grid[pt]]:
+                if adjacent_obj in placed_objects:
+                    # This object has already been placed.
+                    continue
+
+                DiagramGrid._put_object(new_pt, adjacent_obj, grid, [])
+                placed_objects.add(adjacent_obj)
+                placed_objects.update(place_objects(new_pt, placed_objects))
+
+                new_pt = (new_pt[0] + 1, new_pt[1])
+
+            return placed_objects
+
+        place_objects((0, 0), placed_objects)
+
+        return grid
+
+    @staticmethod
+    def _drop_inessential_morphisms(merged_morphisms):
+        r"""
+        Removes those morphisms which should appear in the diagram,
+        but which have no relevance to object layout.
+
+        Currently this removes "loop" morphisms: the non-identity
+        morphisms with the same domains and codomains.
+        """
+        morphisms = [m for m in merged_morphisms if m.domain != m.codomain]
+        return morphisms
+
+    @staticmethod
+    def _get_connected_components(objects, merged_morphisms):
+        """
+        Given a container of morphisms, returns a list of connected
+        components formed by these morphisms.  A connected component
+        is represented by a diagram consisting of the corresponding
+        morphisms.
+        """
+        component_index = {}
+        for o in objects:
+            component_index[o] = None
+
+        # Get the underlying undirected graph of the diagram.
+        adjlist = DiagramGrid._get_undirected_graph(objects, merged_morphisms)
+
+        def traverse_component(object, current_index):
+            """
+            Does a depth-first search traversal of the component
+            containing ``object``.
+            """
+            component_index[object] = current_index
+            for o in adjlist[object]:
+                if component_index[o] is None:
+                    traverse_component(o, current_index)
+
+        # Traverse all components.
+        current_index = 0
+        for o in adjlist:
+            if component_index[o] is None:
+                traverse_component(o, current_index)
+                current_index += 1
+
+        # List the objects of the components.
+        component_objects = [[] for i in range(current_index)]
+        for o, idx in component_index.items():
+            component_objects[idx].append(o)
+
+        # Finally, list the morphisms belonging to each component.
+        #
+        # Note: If some objects are isolated, they will not get any
+        # morphisms at this stage, and since the layout algorithm
+        # relies, we are essentially going to lose this object.
+        # Therefore, check if there are isolated objects and, for each
+        # of them, provide the trivial identity morphism.  It will get
+        # discarded later, but the object will be there.
+
+        component_morphisms = []
+        for component in component_objects:
+            current_morphisms = {}
+            for m in merged_morphisms:
+                if (m.domain in component) and (m.codomain in component):
+                    current_morphisms[m] = merged_morphisms[m]
+
+            if len(component) == 1:
+                # Let's add an identity morphism, for the sake of
+                # surely having morphisms in this component.
+                current_morphisms[IdentityMorphism(component[0])] = FiniteSet()
+
+            component_morphisms.append(Diagram(current_morphisms))
+
+        return component_morphisms
+
+    def __init__(self, diagram, groups=None, **hints):
+        premises = DiagramGrid._simplify_morphisms(diagram.premises)
+        conclusions = DiagramGrid._simplify_morphisms(diagram.conclusions)
+        all_merged_morphisms = DiagramGrid._merge_premises_conclusions(
+            premises, conclusions)
+        merged_morphisms = DiagramGrid._drop_inessential_morphisms(
+            all_merged_morphisms)
+
+        # Store the merged morphisms for later use.
+        self._morphisms = all_merged_morphisms
+
+        components = DiagramGrid._get_connected_components(
+            diagram.objects, all_merged_morphisms)
+
+        if groups and (groups != diagram.objects):
+            # Lay out the diagram according to the groups.
+            self._grid = DiagramGrid._handle_groups(
+                diagram, groups, merged_morphisms, hints)
+        elif len(components) > 1:
+            # Note that we check for connectedness _before_ checking
+            # the layout hints because the layout strategies don't
+            # know how to deal with disconnected diagrams.
+
+            # The diagram is disconnected.  Lay out the components
+            # independently.
+            grids = []
+
+            # Sort the components to eventually get the grids arranged
+            # in a fixed, hash-independent order.
+            components = sorted(components, key=default_sort_key)
+
+            for component in components:
+                grid = DiagramGrid(component, **hints)
+                grids.append(grid)
+
+            # Throw the grids together, in a line.
+            total_width = sum(g.width for g in grids)
+            total_height = max(g.height for g in grids)
+
+            grid = _GrowableGrid(total_width, total_height)
+            start_j = 0
+            for g in grids:
+                for i in range(g.height):
+                    for j in range(g.width):
+                        grid[i, start_j + j] = g[i, j]
+
+                start_j += g.width
+
+            self._grid = grid
+        elif "layout" in hints:
+            if hints["layout"] == "sequential":
+                self._grid = DiagramGrid._sequential_layout(
+                    diagram, merged_morphisms)
+        else:
+            self._grid = DiagramGrid._generic_layout(diagram, merged_morphisms)
+
+        if hints.get("transpose"):
+            # Transpose the resulting grid.
+            grid = _GrowableGrid(self._grid.height, self._grid.width)
+            for i in range(self._grid.height):
+                for j in range(self._grid.width):
+                    grid[j, i] = self._grid[i, j]
+            self._grid = grid
+
+    @property
+    def width(self):
+        """
+        Returns the number of columns in this diagram layout.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> from sympy.categories import Diagram, DiagramGrid
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> diagram = Diagram([f, g])
+        >>> grid = DiagramGrid(diagram)
+        >>> grid.width
+        2
+
+        """
+        return self._grid.width
+
+    @property
+    def height(self):
+        """
+        Returns the number of rows in this diagram layout.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> from sympy.categories import Diagram, DiagramGrid
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> diagram = Diagram([f, g])
+        >>> grid = DiagramGrid(diagram)
+        >>> grid.height
+        2
+
+        """
+        return self._grid.height
+
+    def __getitem__(self, i_j):
+        """
+        Returns the object placed in the row ``i`` and column ``j``.
+        The indices are 0-based.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> from sympy.categories import Diagram, DiagramGrid
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> diagram = Diagram([f, g])
+        >>> grid = DiagramGrid(diagram)
+        >>> (grid[0, 0], grid[0, 1])
+        (Object("A"), Object("B"))
+        >>> (grid[1, 0], grid[1, 1])
+        (None, Object("C"))
+
+        """
+        i, j = i_j
+        return self._grid[i, j]
+
+    @property
+    def morphisms(self):
+        """
+        Returns those morphisms (and their properties) which are
+        sufficiently meaningful to be drawn.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> from sympy.categories import Diagram, DiagramGrid
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> diagram = Diagram([f, g])
+        >>> grid = DiagramGrid(diagram)
+        >>> grid.morphisms
+        {NamedMorphism(Object("A"), Object("B"), "f"): EmptySet,
+        NamedMorphism(Object("B"), Object("C"), "g"): EmptySet}
+
+        """
+        return self._morphisms
+
+    def __str__(self):
+        """
+        Produces a string representation of this class.
+
+        This method returns a string representation of the underlying
+        list of lists of objects.
+
+        Examples
+        ========
+
+        >>> from sympy.categories import Object, NamedMorphism
+        >>> from sympy.categories import Diagram, DiagramGrid
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> diagram = Diagram([f, g])
+        >>> grid = DiagramGrid(diagram)
+        >>> print(grid)
+        [[Object("A"), Object("B")],
+        [None, Object("C")]]
+
+        """
+        return repr(self._grid._array)
+
+
+class ArrowStringDescription:
+    r"""
+    Stores the information necessary for producing an Xy-pic
+    description of an arrow.
+
+    The principal goal of this class is to abstract away the string
+    representation of an arrow and to also provide the functionality
+    to produce the actual Xy-pic string.
+
+    ``unit`` sets the unit which will be used to specify the amount of
+    curving and other distances.  ``horizontal_direction`` should be a
+    string of ``"r"`` or ``"l"`` specifying the horizontal offset of the
+    target cell of the arrow relatively to the current one.
+    ``vertical_direction`` should  specify the vertical offset using a
+    series of either ``"d"`` or ``"u"``.  ``label_position`` should be
+    either ``"^"``, ``"_"``,  or ``"|"`` to specify that the label should
+    be positioned above the arrow, below the arrow or just over the arrow,
+    in a break.  Note that the notions "above" and "below" are relative
+    to arrow direction.  ``label`` stores the morphism label.
+
+    This works as follows (disregard the yet unexplained arguments):
+
+    >>> from sympy.categories.diagram_drawing import ArrowStringDescription
+    >>> astr = ArrowStringDescription(
+    ... unit="mm", curving=None, curving_amount=None,
+    ... looping_start=None, looping_end=None, horizontal_direction="d",
+    ... vertical_direction="r", label_position="_", label="f")
+    >>> print(str(astr))
+    \ar[dr]_{f}
+
+    ``curving`` should be one of ``"^"``, ``"_"`` to specify in which
+    direction the arrow is going to curve. ``curving_amount`` is a number
+    describing how many ``unit``'s the morphism is going to curve:
+
+    >>> astr = ArrowStringDescription(
+    ... unit="mm", curving="^", curving_amount=12,
+    ... looping_start=None, looping_end=None, horizontal_direction="d",
+    ... vertical_direction="r", label_position="_", label="f")
+    >>> print(str(astr))
+    \ar@/^12mm/[dr]_{f}
+
+    ``looping_start`` and ``looping_end`` are currently only used for
+    loop morphisms, those which have the same domain and codomain.
+    These two attributes should store a valid Xy-pic direction and
+    specify, correspondingly, the direction the arrow gets out into
+    and the direction the arrow gets back from:
+
+    >>> astr = ArrowStringDescription(
+    ... unit="mm", curving=None, curving_amount=None,
+    ... looping_start="u", looping_end="l", horizontal_direction="",
+    ... vertical_direction="", label_position="_", label="f")
+    >>> print(str(astr))
+    \ar@(u,l)[]_{f}
+
+    ``label_displacement`` controls how far the arrow label is from
+    the ends of the arrow.  For example, to position the arrow label
+    near the arrow head, use ">":
+
+    >>> astr = ArrowStringDescription(
+    ... unit="mm", curving="^", curving_amount=12,
+    ... looping_start=None, looping_end=None, horizontal_direction="d",
+    ... vertical_direction="r", label_position="_", label="f")
+    >>> astr.label_displacement = ">"
+    >>> print(str(astr))
+    \ar@/^12mm/[dr]_>{f}
+
+    Finally, ``arrow_style`` is used to specify the arrow style.  To
+    get a dashed arrow, for example, use "{-->}" as arrow style:
+
+    >>> astr = ArrowStringDescription(
+    ... unit="mm", curving="^", curving_amount=12,
+    ... looping_start=None, looping_end=None, horizontal_direction="d",
+    ... vertical_direction="r", label_position="_", label="f")
+    >>> astr.arrow_style = "{-->}"
+    >>> print(str(astr))
+    \ar@/^12mm/@{-->}[dr]_{f}
+
+    Notes
+    =====
+
+    Instances of :class:`ArrowStringDescription` will be constructed
+    by :class:`XypicDiagramDrawer` and provided for further use in
+    formatters.  The user is not expected to construct instances of
+    :class:`ArrowStringDescription` themselves.
+
+    To be able to properly utilise this class, the reader is encouraged
+    to checkout the Xy-pic user guide, available at [Xypic].
+
+    See Also
+    ========
+
+    XypicDiagramDrawer
+
+    References
+    ==========
+
+    .. [Xypic] https://xy-pic.sourceforge.net/
+    """
+    def __init__(self, unit, curving, curving_amount, looping_start,
+                 looping_end, horizontal_direction, vertical_direction,
+                 label_position, label):
+        self.unit = unit
+        self.curving = curving
+        self.curving_amount = curving_amount
+        self.looping_start = looping_start
+        self.looping_end = looping_end
+        self.horizontal_direction = horizontal_direction
+        self.vertical_direction = vertical_direction
+        self.label_position = label_position
+        self.label = label
+
+        self.label_displacement = ""
+        self.arrow_style = ""
+
+        # This flag shows that the position of the label of this
+        # morphism was set while typesetting a curved morphism and
+        # should not be modified later.
+        self.forced_label_position = False
+
+    def __str__(self):
+        if self.curving:
+            curving_str = "@/%s%d%s/" % (self.curving, self.curving_amount,
+                                         self.unit)
+        else:
+            curving_str = ""
+
+        if self.looping_start and self.looping_end:
+            looping_str = "@(%s,%s)" % (self.looping_start, self.looping_end)
+        else:
+            looping_str = ""
+
+        if self.arrow_style:
+
+            style_str = "@" + self.arrow_style
+        else:
+            style_str = ""
+
+        return "\\ar%s%s%s[%s%s]%s%s{%s}" % \
+               (curving_str, looping_str, style_str, self.horizontal_direction,
+                self.vertical_direction, self.label_position,
+                self.label_displacement, self.label)
+
+
+class XypicDiagramDrawer:
+    r"""
+    Given a :class:`~.Diagram` and the corresponding
+    :class:`DiagramGrid`, produces the Xy-pic representation of the
+    diagram.
+
+    The most important method in this class is ``draw``.  Consider the
+    following triangle diagram:
+
+    >>> from sympy.categories import Object, NamedMorphism, Diagram
+    >>> from sympy.categories import DiagramGrid, XypicDiagramDrawer
+    >>> A = Object("A")
+    >>> B = Object("B")
+    >>> C = Object("C")
+    >>> f = NamedMorphism(A, B, "f")
+    >>> g = NamedMorphism(B, C, "g")
+    >>> diagram = Diagram([f, g], {g * f: "unique"})
+
+    To draw this diagram, its objects need to be laid out with a
+    :class:`DiagramGrid`::
+
+    >>> grid = DiagramGrid(diagram)
+
+    Finally, the drawing:
+
+    >>> drawer = XypicDiagramDrawer()
+    >>> print(drawer.draw(diagram, grid))
+    \xymatrix{
+    A \ar[d]_{g\circ f} \ar[r]^{f} & B \ar[ld]^{g} \\
+    C &
+    }
+
+    For further details see the docstring of this method.
+
+    To control the appearance of the arrows, formatters are used.  The
+    dictionary ``arrow_formatters`` maps morphisms to formatter
+    functions.  A formatter is accepts an
+    :class:`ArrowStringDescription` and is allowed to modify any of
+    the arrow properties exposed thereby.  For example, to have all
+    morphisms with the property ``unique`` appear as dashed arrows,
+    and to have their names prepended with `\exists !`, the following
+    should be done:
+
+    >>> def formatter(astr):
+    ...   astr.label = r"\exists !" + astr.label
+    ...   astr.arrow_style = "{-->}"
+    >>> drawer.arrow_formatters["unique"] = formatter
+    >>> print(drawer.draw(diagram, grid))
+    \xymatrix{
+    A \ar@{-->}[d]_{\exists !g\circ f} \ar[r]^{f} & B \ar[ld]^{g} \\
+    C &
+    }
+
+    To modify the appearance of all arrows in the diagram, set
+    ``default_arrow_formatter``.  For example, to place all morphism
+    labels a little bit farther from the arrow head so that they look
+    more centred, do as follows:
+
+    >>> def default_formatter(astr):
+    ...   astr.label_displacement = "(0.45)"
+    >>> drawer.default_arrow_formatter = default_formatter
+    >>> print(drawer.draw(diagram, grid))
+    \xymatrix{
+    A \ar@{-->}[d]_(0.45){\exists !g\circ f} \ar[r]^(0.45){f} & B \ar[ld]^(0.45){g} \\
+    C &
+    }
+
+    In some diagrams some morphisms are drawn as curved arrows.
+    Consider the following diagram:
+
+    >>> D = Object("D")
+    >>> E = Object("E")
+    >>> h = NamedMorphism(D, A, "h")
+    >>> k = NamedMorphism(D, B, "k")
+    >>> diagram = Diagram([f, g, h, k])
+    >>> grid = DiagramGrid(diagram)
+    >>> drawer = XypicDiagramDrawer()
+    >>> print(drawer.draw(diagram, grid))
+    \xymatrix{
+    A \ar[r]_{f} & B \ar[d]^{g} & D \ar[l]^{k} \ar@/_3mm/[ll]_{h} \\
+    & C &
+    }
+
+    To control how far the morphisms are curved by default, one can
+    use the ``unit`` and ``default_curving_amount`` attributes:
+
+    >>> drawer.unit = "cm"
+    >>> drawer.default_curving_amount = 1
+    >>> print(drawer.draw(diagram, grid))
+    \xymatrix{
+    A \ar[r]_{f} & B \ar[d]^{g} & D \ar[l]^{k} \ar@/_1cm/[ll]_{h} \\
+    & C &
+    }
+
+    In some diagrams, there are multiple curved morphisms between the
+    same two objects.  To control by how much the curving changes
+    between two such successive morphisms, use
+    ``default_curving_step``:
+
+    >>> drawer.default_curving_step = 1
+    >>> h1 = NamedMorphism(A, D, "h1")
+    >>> diagram = Diagram([f, g, h, k, h1])
+    >>> grid = DiagramGrid(diagram)
+    >>> print(drawer.draw(diagram, grid))
+    \xymatrix{
+    A \ar[r]_{f} \ar@/^1cm/[rr]^{h_{1}} & B \ar[d]^{g} & D \ar[l]^{k} \ar@/_2cm/[ll]_{h} \\
+    & C &
+    }
+
+    The default value of ``default_curving_step`` is 4 units.
+
+    See Also
+    ========
+
+    draw, ArrowStringDescription
+    """
+    def __init__(self):
+        self.unit = "mm"
+        self.default_curving_amount = 3
+        self.default_curving_step = 4
+
+        # This dictionary maps properties to the corresponding arrow
+        # formatters.
+        self.arrow_formatters = {}
+
+        # This is the default arrow formatter which will be applied to
+        # each arrow independently of its properties.
+        self.default_arrow_formatter = None
+
+    @staticmethod
+    def _process_loop_morphism(i, j, grid, morphisms_str_info, object_coords):
+        """
+        Produces the information required for constructing the string
+        representation of a loop morphism.  This function is invoked
+        from ``_process_morphism``.
+
+        See Also
+        ========
+
+        _process_morphism
+        """
+        curving = ""
+        label_pos = "^"
+        looping_start = ""
+        looping_end = ""
+
+        # This is a loop morphism.  Count how many morphisms stick
+        # in each of the four quadrants.  Note that straight
+        # vertical and horizontal morphisms count in two quadrants
+        # at the same time (i.e., a morphism going up counts both
+        # in the first and the second quadrants).
+
+        # The usual numbering (counterclockwise) of quadrants
+        # applies.
+        quadrant = [0, 0, 0, 0]
+
+        obj = grid[i, j]
+
+        for m, m_str_info in morphisms_str_info.items():
+            if (m.domain == obj) and (m.codomain == obj):
+                # That's another loop morphism.  Check how it
+                # loops and mark the corresponding quadrants as
+                # busy.
+                (l_s, l_e) = (m_str_info.looping_start, m_str_info.looping_end)
+
+                if (l_s, l_e) == ("r", "u"):
+                    quadrant[0] += 1
+                elif (l_s, l_e) == ("u", "l"):
+                    quadrant[1] += 1
+                elif (l_s, l_e) == ("l", "d"):
+                    quadrant[2] += 1
+                elif (l_s, l_e) == ("d", "r"):
+                    quadrant[3] += 1
+
+                continue
+            if m.domain == obj:
+                (end_i, end_j) = object_coords[m.codomain]
+                goes_out = True
+            elif m.codomain == obj:
+                (end_i, end_j) = object_coords[m.domain]
+                goes_out = False
+            else:
+                continue
+
+            d_i = end_i - i
+            d_j = end_j - j
+            m_curving = m_str_info.curving
+
+            if (d_i != 0) and (d_j != 0):
+                # This is really a diagonal morphism.  Detect the
+                # quadrant.
+                if (d_i > 0) and (d_j > 0):
+                    quadrant[0] += 1
+                elif (d_i > 0) and (d_j < 0):
+                    quadrant[1] += 1
+                elif (d_i < 0) and (d_j < 0):
+                    quadrant[2] += 1
+                elif (d_i < 0) and (d_j > 0):
+                    quadrant[3] += 1
+            elif d_i == 0:
+                # Knowing where the other end of the morphism is
+                # and which way it goes, we now have to decide
+                # which quadrant is now the upper one and which is
+                # the lower one.
+                if d_j > 0:
+                    if goes_out:
+                        upper_quadrant = 0
+                        lower_quadrant = 3
+                    else:
+                        upper_quadrant = 3
+                        lower_quadrant = 0
+                else:
+                    if goes_out:
+                        upper_quadrant = 2
+                        lower_quadrant = 1
+                    else:
+                        upper_quadrant = 1
+                        lower_quadrant = 2
+
+                if m_curving:
+                    if m_curving == "^":
+                        quadrant[upper_quadrant] += 1
+                    elif m_curving == "_":
+                        quadrant[lower_quadrant] += 1
+                else:
+                    # This morphism counts in both upper and lower
+                    # quadrants.
+                    quadrant[upper_quadrant] += 1
+                    quadrant[lower_quadrant] += 1
+            elif d_j == 0:
+                # Knowing where the other end of the morphism is
+                # and which way it goes, we now have to decide
+                # which quadrant is now the left one and which is
+                # the right one.
+                if d_i < 0:
+                    if goes_out:
+                        left_quadrant = 1
+                        right_quadrant = 0
+                    else:
+                        left_quadrant = 0
+                        right_quadrant = 1
+                else:
+                    if goes_out:
+                        left_quadrant = 3
+                        right_quadrant = 2
+                    else:
+                        left_quadrant = 2
+                        right_quadrant = 3
+
+                if m_curving:
+                    if m_curving == "^":
+                        quadrant[left_quadrant] += 1
+                    elif m_curving == "_":
+                        quadrant[right_quadrant] += 1
+                else:
+                    # This morphism counts in both upper and lower
+                    # quadrants.
+                    quadrant[left_quadrant] += 1
+                    quadrant[right_quadrant] += 1
+
+        # Pick the freest quadrant to curve our morphism into.
+        freest_quadrant = 0
+        for i in range(4):
+            if quadrant[i] < quadrant[freest_quadrant]:
+                freest_quadrant = i
+
+        # Now set up proper looping.
+        (looping_start, looping_end) = [("r", "u"), ("u", "l"), ("l", "d"),
+                                        ("d", "r")][freest_quadrant]
+
+        return (curving, label_pos, looping_start, looping_end)
+
+    @staticmethod
+    def _process_horizontal_morphism(i, j, target_j, grid, morphisms_str_info,
+                                     object_coords):
+        """
+        Produces the information required for constructing the string
+        representation of a horizontal morphism.  This function is
+        invoked from ``_process_morphism``.
+
+        See Also
+        ========
+
+        _process_morphism
+        """
+        # The arrow is horizontal.  Check if it goes from left to
+        # right (``backwards == False``) or from right to left
+        # (``backwards == True``).
+        backwards = False
+        start = j
+        end = target_j
+        if end < start:
+            (start, end) = (end, start)
+            backwards = True
+
+        # Let's see which objects are there between ``start`` and
+        # ``end``, and then count how many morphisms stick out
+        # upwards, and how many stick out downwards.
+        #
+        # For example, consider the situation:
+        #
+        #    B1 C1
+        #    |  |
+        # A--B--C--D
+        #    |
+        #    B2
+        #
+        # Between the objects `A` and `D` there are two objects:
+        # `B` and `C`.  Further, there are two morphisms which
+        # stick out upward (the ones between `B1` and `B` and
+        # between `C` and `C1`) and one morphism which sticks out
+        # downward (the one between `B and `B2`).
+        #
+        # We need this information to decide how to curve the
+        # arrow between `A` and `D`.  First of all, since there
+        # are two objects between `A` and `D``, we must curve the
+        # arrow.  Then, we will have it curve downward, because
+        # there is more space (less morphisms stick out downward
+        # than upward).
+        up = []
+        down = []
+        straight_horizontal = []
+        for k in range(start + 1, end):
+            obj = grid[i, k]
+            if not obj:
+                continue
+
+            for m in morphisms_str_info:
+                if m.domain == obj:
+                    (end_i, end_j) = object_coords[m.codomain]
+                elif m.codomain == obj:
+                    (end_i, end_j) = object_coords[m.domain]
+                else:
+                    continue
+
+                if end_i > i:
+                    down.append(m)
+                elif end_i < i:
+                    up.append(m)
+                elif not morphisms_str_info[m].curving:
+                    # This is a straight horizontal morphism,
+                    # because it has no curving.
+                    straight_horizontal.append(m)
+
+        if len(up) < len(down):
+            # More morphisms stick out downward than upward, let's
+            # curve the morphism up.
+            if backwards:
+                curving = "_"
+                label_pos = "_"
+            else:
+                curving = "^"
+                label_pos = "^"
+
+            # Assure that the straight horizontal morphisms have
+            # their labels on the lower side of the arrow.
+            for m in straight_horizontal:
+                (i1, j1) = object_coords[m.domain]
+                (i2, j2) = object_coords[m.codomain]
+
+                m_str_info = morphisms_str_info[m]
+                if j1 < j2:
+                    m_str_info.label_position = "_"
+                else:
+                    m_str_info.label_position = "^"
+
+                # Don't allow any further modifications of the
+                # position of this label.
+                m_str_info.forced_label_position = True
+        else:
+            # More morphisms stick out downward than upward, let's
+            # curve the morphism up.
+            if backwards:
+                curving = "^"
+                label_pos = "^"
+            else:
+                curving = "_"
+                label_pos = "_"
+
+            # Assure that the straight horizontal morphisms have
+            # their labels on the upper side of the arrow.
+            for m in straight_horizontal:
+                (i1, j1) = object_coords[m.domain]
+                (i2, j2) = object_coords[m.codomain]
+
+                m_str_info = morphisms_str_info[m]
+                if j1 < j2:
+                    m_str_info.label_position = "^"
+                else:
+                    m_str_info.label_position = "_"
+
+                # Don't allow any further modifications of the
+                # position of this label.
+                m_str_info.forced_label_position = True
+
+        return (curving, label_pos)
+
+    @staticmethod
+    def _process_vertical_morphism(i, j, target_i, grid, morphisms_str_info,
+                                   object_coords):
+        """
+        Produces the information required for constructing the string
+        representation of a vertical morphism.  This function is
+        invoked from ``_process_morphism``.
+
+        See Also
+        ========
+
+        _process_morphism
+        """
+        # This arrow is vertical.  Check if it goes from top to
+        # bottom (``backwards == False``) or from bottom to top
+        # (``backwards == True``).
+        backwards = False
+        start = i
+        end = target_i
+        if end < start:
+            (start, end) = (end, start)
+            backwards = True
+
+        # Let's see which objects are there between ``start`` and
+        # ``end``, and then count how many morphisms stick out to
+        # the left, and how many stick out to the right.
+        #
+        # See the corresponding comment in the previous branch of
+        # this if-statement for more details.
+        left = []
+        right = []
+        straight_vertical = []
+        for k in range(start + 1, end):
+            obj = grid[k, j]
+            if not obj:
+                continue
+
+            for m in morphisms_str_info:
+                if m.domain == obj:
+                    (end_i, end_j) = object_coords[m.codomain]
+                elif m.codomain == obj:
+                    (end_i, end_j) = object_coords[m.domain]
+                else:
+                    continue
+
+                if end_j > j:
+                    right.append(m)
+                elif end_j < j:
+                    left.append(m)
+                elif not morphisms_str_info[m].curving:
+                    # This is a straight vertical morphism,
+                    # because it has no curving.
+                    straight_vertical.append(m)
+
+        if len(left) < len(right):
+            # More morphisms stick out to the left than to the
+            # right, let's curve the morphism to the right.
+            if backwards:
+                curving = "^"
+                label_pos = "^"
+            else:
+                curving = "_"
+                label_pos = "_"
+
+            # Assure that the straight vertical morphisms have
+            # their labels on the left side of the arrow.
+            for m in straight_vertical:
+                (i1, j1) = object_coords[m.domain]
+                (i2, j2) = object_coords[m.codomain]
+
+                m_str_info = morphisms_str_info[m]
+                if i1 < i2:
+                    m_str_info.label_position = "^"
+                else:
+                    m_str_info.label_position = "_"
+
+                # Don't allow any further modifications of the
+                # position of this label.
+                m_str_info.forced_label_position = True
+        else:
+            # More morphisms stick out to the right than to the
+            # left, let's curve the morphism to the left.
+            if backwards:
+                curving = "_"
+                label_pos = "_"
+            else:
+                curving = "^"
+                label_pos = "^"
+
+            # Assure that the straight vertical morphisms have
+            # their labels on the right side of the arrow.
+            for m in straight_vertical:
+                (i1, j1) = object_coords[m.domain]
+                (i2, j2) = object_coords[m.codomain]
+
+                m_str_info = morphisms_str_info[m]
+                if i1 < i2:
+                    m_str_info.label_position = "_"
+                else:
+                    m_str_info.label_position = "^"
+
+                # Don't allow any further modifications of the
+                # position of this label.
+                m_str_info.forced_label_position = True
+
+        return (curving, label_pos)
+
+    def _process_morphism(self, diagram, grid, morphism, object_coords,
+                          morphisms, morphisms_str_info):
+        """
+        Given the required information, produces the string
+        representation of ``morphism``.
+        """
+        def repeat_string_cond(times, str_gt, str_lt):
+            """
+            If ``times > 0``, repeats ``str_gt`` ``times`` times.
+            Otherwise, repeats ``str_lt`` ``-times`` times.
+            """
+            if times > 0:
+                return str_gt * times
+            else:
+                return str_lt * (-times)
+
+        def count_morphisms_undirected(A, B):
+            """
+            Counts how many processed morphisms there are between the
+            two supplied objects.
+            """
+            return len([m for m in morphisms_str_info
+                        if {m.domain, m.codomain} == {A, B}])
+
+        def count_morphisms_filtered(dom, cod, curving):
+            """
+            Counts the processed morphisms which go out of ``dom``
+            into ``cod`` with curving ``curving``.
+            """
+            return len([m for m, m_str_info in morphisms_str_info.items()
+                        if (m.domain, m.codomain) == (dom, cod) and
+                        (m_str_info.curving == curving)])
+
+        (i, j) = object_coords[morphism.domain]
+        (target_i, target_j) = object_coords[morphism.codomain]
+
+        # We now need to determine the direction of
+        # the arrow.
+        delta_i = target_i - i
+        delta_j = target_j - j
+        vertical_direction = repeat_string_cond(delta_i,
+                                                "d", "u")
+        horizontal_direction = repeat_string_cond(delta_j,
+                                                  "r", "l")
+
+        curving = ""
+        label_pos = "^"
+        looping_start = ""
+        looping_end = ""
+
+        if (delta_i == 0) and (delta_j == 0):
+            # This is a loop morphism.
+            (curving, label_pos, looping_start,
+             looping_end) = XypicDiagramDrawer._process_loop_morphism(
+                 i, j, grid, morphisms_str_info, object_coords)
+        elif (delta_i == 0) and (abs(j - target_j) > 1):
+            # This is a horizontal morphism.
+            (curving, label_pos) = XypicDiagramDrawer._process_horizontal_morphism(
+                i, j, target_j, grid, morphisms_str_info, object_coords)
+        elif (delta_j == 0) and (abs(i - target_i) > 1):
+            # This is a vertical morphism.
+            (curving, label_pos) = XypicDiagramDrawer._process_vertical_morphism(
+                i, j, target_i, grid, morphisms_str_info, object_coords)
+
+        count = count_morphisms_undirected(morphism.domain, morphism.codomain)
+        curving_amount = ""
+        if curving:
+            # This morphisms should be curved anyway.
+            curving_amount = self.default_curving_amount + count * \
+                self.default_curving_step
+        elif count:
+            # There are no objects between the domain and codomain of
+            # the current morphism, but this is not there already are
+            # some morphisms with the same domain and codomain, so we
+            # have to curve this one.
+            curving = "^"
+            filtered_morphisms = count_morphisms_filtered(
+                morphism.domain, morphism.codomain, curving)
+            curving_amount = self.default_curving_amount + \
+                filtered_morphisms * \
+                self.default_curving_step
+
+        # Let's now get the name of the morphism.
+        morphism_name = ""
+        if isinstance(morphism, IdentityMorphism):
+            morphism_name = "id_{%s}" + latex(grid[i, j])
+        elif isinstance(morphism, CompositeMorphism):
+            component_names = [latex(Symbol(component.name)) for
+                               component in morphism.components]
+            component_names.reverse()
+            morphism_name = "\\circ ".join(component_names)
+        elif isinstance(morphism, NamedMorphism):
+            morphism_name = latex(Symbol(morphism.name))
+
+        return ArrowStringDescription(
+            self.unit, curving, curving_amount, looping_start,
+            looping_end, horizontal_direction, vertical_direction,
+            label_pos, morphism_name)
+
+    @staticmethod
+    def _check_free_space_horizontal(dom_i, dom_j, cod_j, grid):
+        """
+        For a horizontal morphism, checks whether there is free space
+        (i.e., space not occupied by any objects) above the morphism
+        or below it.
+        """
+        if dom_j < cod_j:
+            (start, end) = (dom_j, cod_j)
+            backwards = False
+        else:
+            (start, end) = (cod_j, dom_j)
+            backwards = True
+
+        # Check for free space above.
+        if dom_i == 0:
+            free_up = True
+        else:
+            free_up = all(grid[dom_i - 1, j] for j in
+                          range(start, end + 1))
+
+        # Check for free space below.
+        if dom_i == grid.height - 1:
+            free_down = True
+        else:
+            free_down = not any(grid[dom_i + 1, j] for j in
+                                range(start, end + 1))
+
+        return (free_up, free_down, backwards)
+
+    @staticmethod
+    def _check_free_space_vertical(dom_i, cod_i, dom_j, grid):
+        """
+        For a vertical morphism, checks whether there is free space
+        (i.e., space not occupied by any objects) to the left of the
+        morphism or to the right of it.
+        """
+        if dom_i < cod_i:
+            (start, end) = (dom_i, cod_i)
+            backwards = False
+        else:
+            (start, end) = (cod_i, dom_i)
+            backwards = True
+
+        # Check if there's space to the left.
+        if dom_j == 0:
+            free_left = True
+        else:
+            free_left = not any(grid[i, dom_j - 1] for i in
+                                range(start, end + 1))
+
+        if dom_j == grid.width - 1:
+            free_right = True
+        else:
+            free_right = not any(grid[i, dom_j + 1] for i in
+                                 range(start, end + 1))
+
+        return (free_left, free_right, backwards)
+
+    @staticmethod
+    def _check_free_space_diagonal(dom_i, cod_i, dom_j, cod_j, grid):
+        """
+        For a diagonal morphism, checks whether there is free space
+        (i.e., space not occupied by any objects) above the morphism
+        or below it.
+        """
+        def abs_xrange(start, end):
+            if start < end:
+                return range(start, end + 1)
+            else:
+                return range(end, start + 1)
+
+        if dom_i < cod_i and dom_j < cod_j:
+            # This morphism goes from top-left to
+            # bottom-right.
+            (start_i, start_j) = (dom_i, dom_j)
+            (end_i, end_j) = (cod_i, cod_j)
+            backwards = False
+        elif dom_i > cod_i and dom_j > cod_j:
+            # This morphism goes from bottom-right to
+            # top-left.
+            (start_i, start_j) = (cod_i, cod_j)
+            (end_i, end_j) = (dom_i, dom_j)
+            backwards = True
+        if dom_i < cod_i and dom_j > cod_j:
+            # This morphism goes from top-right to
+            # bottom-left.
+            (start_i, start_j) = (dom_i, dom_j)
+            (end_i, end_j) = (cod_i, cod_j)
+            backwards = True
+        elif dom_i > cod_i and dom_j < cod_j:
+            # This morphism goes from bottom-left to
+            # top-right.
+            (start_i, start_j) = (cod_i, cod_j)
+            (end_i, end_j) = (dom_i, dom_j)
+            backwards = False
+
+        # This is an attempt at a fast and furious strategy to
+        # decide where there is free space on the two sides of
+        # a diagonal morphism.  For a diagonal morphism
+        # starting at ``(start_i, start_j)`` and ending at
+        # ``(end_i, end_j)`` the rectangle defined by these
+        # two points is considered.  The slope of the diagonal
+        # ``alpha`` is then computed.  Then, for every cell
+        # ``(i, j)`` within the rectangle, the slope
+        # ``alpha1`` of the line through ``(start_i,
+        # start_j)`` and ``(i, j)`` is considered.  If
+        # ``alpha1`` is between 0 and ``alpha``, the point
+        # ``(i, j)`` is above the diagonal, if ``alpha1`` is
+        # between ``alpha`` and infinity, the point is below
+        # the diagonal.  Also note that, with some beforehand
+        # precautions, this trick works for both the main and
+        # the secondary diagonals of the rectangle.
+
+        # I have considered the possibility to only follow the
+        # shorter diagonals immediately above and below the
+        # main (or secondary) diagonal.  This, however,
+        # wouldn't have resulted in much performance gain or
+        # better detection of outer edges, because of
+        # relatively small sizes of diagram grids, while the
+        # code would have become harder to understand.
+
+        alpha = float(end_i - start_i)/(end_j - start_j)
+        free_up = True
+        free_down = True
+        for i in abs_xrange(start_i, end_i):
+            if not free_up and not free_down:
+                break
+
+            for j in abs_xrange(start_j, end_j):
+                if not free_up and not free_down:
+                    break
+
+                if (i, j) == (start_i, start_j):
+                    continue
+
+                if j == start_j:
+                    alpha1 = "inf"
+                else:
+                    alpha1 = float(i - start_i)/(j - start_j)
+
+                if grid[i, j]:
+                    if (alpha1 == "inf") or (abs(alpha1) > abs(alpha)):
+                        free_down = False
+                    elif abs(alpha1) < abs(alpha):
+                        free_up = False
+
+        return (free_up, free_down, backwards)
+
+    def _push_labels_out(self, morphisms_str_info, grid, object_coords):
+        """
+        For all straight morphisms which form the visual boundary of
+        the laid out diagram, puts their labels on their outer sides.
+        """
+        def set_label_position(free1, free2, pos1, pos2, backwards, m_str_info):
+            """
+            Given the information about room available to one side and
+            to the other side of a morphism (``free1`` and ``free2``),
+            sets the position of the morphism label in such a way that
+            it is on the freer side.  This latter operations involves
+            choice between ``pos1`` and ``pos2``, taking ``backwards``
+            in consideration.
+
+            Thus this function will do nothing if either both ``free1
+            == True`` and ``free2 == True`` or both ``free1 == False``
+            and ``free2 == False``.  In either case, choosing one side
+            over the other presents no advantage.
+            """
+            if backwards:
+                (pos1, pos2) = (pos2, pos1)
+
+            if free1 and not free2:
+                m_str_info.label_position = pos1
+            elif free2 and not free1:
+                m_str_info.label_position = pos2
+
+        for m, m_str_info in morphisms_str_info.items():
+            if m_str_info.curving or m_str_info.forced_label_position:
+                # This is either a curved morphism, and curved
+                # morphisms have other magic, or the position of this
+                # label has already been fixed.
+                continue
+
+            if m.domain == m.codomain:
+                # This is a loop morphism, their labels, again have a
+                # different magic.
+                continue
+
+            (dom_i, dom_j) = object_coords[m.domain]
+            (cod_i, cod_j) = object_coords[m.codomain]
+
+            if dom_i == cod_i:
+                # Horizontal morphism.
+                (free_up, free_down,
+                 backwards) = XypicDiagramDrawer._check_free_space_horizontal(
+                     dom_i, dom_j, cod_j, grid)
+
+                set_label_position(free_up, free_down, "^", "_",
+                                   backwards, m_str_info)
+            elif dom_j == cod_j:
+                # Vertical morphism.
+                (free_left, free_right,
+                 backwards) = XypicDiagramDrawer._check_free_space_vertical(
+                     dom_i, cod_i, dom_j, grid)
+
+                set_label_position(free_left, free_right, "_", "^",
+                                   backwards, m_str_info)
+            else:
+                # A diagonal morphism.
+                (free_up, free_down,
+                 backwards) = XypicDiagramDrawer._check_free_space_diagonal(
+                     dom_i, cod_i, dom_j, cod_j, grid)
+
+                set_label_position(free_up, free_down, "^", "_",
+                                   backwards, m_str_info)
+
+    @staticmethod
+    def _morphism_sort_key(morphism, object_coords):
+        """
+        Provides a morphism sorting key such that horizontal or
+        vertical morphisms between neighbouring objects come
+        first, then horizontal or vertical morphisms between more
+        far away objects, and finally, all other morphisms.
+        """
+        (i, j) = object_coords[morphism.domain]
+        (target_i, target_j) = object_coords[morphism.codomain]
+
+        if morphism.domain == morphism.codomain:
+            # Loop morphisms should get after diagonal morphisms
+            # so that the proper direction in which to curve the
+            # loop can be determined.
+            return (3, 0, default_sort_key(morphism))
+
+        if target_i == i:
+            return (1, abs(target_j - j), default_sort_key(morphism))
+
+        if target_j == j:
+            return (1, abs(target_i - i), default_sort_key(morphism))
+
+        # Diagonal morphism.
+        return (2, 0, default_sort_key(morphism))
+
+    @staticmethod
+    def _build_xypic_string(diagram, grid, morphisms,
+                            morphisms_str_info, diagram_format):
+        """
+        Given a collection of :class:`ArrowStringDescription`
+        describing the morphisms of a diagram and the object layout
+        information of a diagram, produces the final Xy-pic picture.
+        """
+        # Build the mapping between objects and morphisms which have
+        # them as domains.
+        object_morphisms = {}
+        for obj in diagram.objects:
+            object_morphisms[obj] = []
+        for morphism in morphisms:
+            object_morphisms[morphism.domain].append(morphism)
+
+        result = "\\xymatrix%s{\n" % diagram_format
+
+        for i in range(grid.height):
+            for j in range(grid.width):
+                obj = grid[i, j]
+                if obj:
+                    result += latex(obj) + " "
+
+                    morphisms_to_draw = object_morphisms[obj]
+                    for morphism in morphisms_to_draw:
+                        result += str(morphisms_str_info[morphism]) + " "
+
+                # Don't put the & after the last column.
+                if j < grid.width - 1:
+                    result += "& "
+
+            # Don't put the line break after the last row.
+            if i < grid.height - 1:
+                result += "\\\\"
+            result += "\n"
+
+        result += "}\n"
+
+        return result
+
+    def draw(self, diagram, grid, masked=None, diagram_format=""):
+        r"""
+        Returns the Xy-pic representation of ``diagram`` laid out in
+        ``grid``.
+
+        Consider the following simple triangle diagram.
+
+        >>> from sympy.categories import Object, NamedMorphism, Diagram
+        >>> from sympy.categories import DiagramGrid, XypicDiagramDrawer
+        >>> A = Object("A")
+        >>> B = Object("B")
+        >>> C = Object("C")
+        >>> f = NamedMorphism(A, B, "f")
+        >>> g = NamedMorphism(B, C, "g")
+        >>> diagram = Diagram([f, g], {g * f: "unique"})
+
+        To draw this diagram, its objects need to be laid out with a
+        :class:`DiagramGrid`::
+
+        >>> grid = DiagramGrid(diagram)
+
+        Finally, the drawing:
+
+        >>> drawer = XypicDiagramDrawer()
+        >>> print(drawer.draw(diagram, grid))
+        \xymatrix{
+        A \ar[d]_{g\circ f} \ar[r]^{f} & B \ar[ld]^{g} \\
+        C &
+        }
+
+        The argument ``masked`` can be used to skip morphisms in the
+        presentation of the diagram:
+
+        >>> print(drawer.draw(diagram, grid, masked=[g * f]))
+        \xymatrix{
+        A \ar[r]^{f} & B \ar[ld]^{g} \\
+        C &
+        }
+
+        Finally, the ``diagram_format`` argument can be used to
+        specify the format string of the diagram.  For example, to
+        increase the spacing by 1 cm, proceeding as follows:
+
+        >>> print(drawer.draw(diagram, grid, diagram_format="@+1cm"))
+        \xymatrix@+1cm{
+        A \ar[d]_{g\circ f} \ar[r]^{f} & B \ar[ld]^{g} \\
+        C &
+        }
+
+        """
+        # This method works in several steps.  It starts by removing
+        # the masked morphisms, if necessary, and then maps objects to
+        # their positions in the grid (coordinate tuples).  Remember
+        # that objects are unique in ``Diagram`` and in the layout
+        # produced by ``DiagramGrid``, so every object is mapped to a
+        # single coordinate pair.
+        #
+        # The next step is the central step and is concerned with
+        # analysing the morphisms of the diagram and deciding how to
+        # draw them.  For example, how to curve the arrows is decided
+        # at this step.  The bulk of the analysis is implemented in
+        # ``_process_morphism``, to the result of which the
+        # appropriate formatters are applied.
+        #
+        # The result of the previous step is a list of
+        # ``ArrowStringDescription``.  After the analysis and
+        # application of formatters, some extra logic tries to assure
+        # better positioning of morphism labels (for example, an
+        # attempt is made to avoid the situations when arrows cross
+        # labels).  This functionality constitutes the next step and
+        # is implemented in ``_push_labels_out``.  Note that label
+        # positions which have been set via a formatter are not
+        # affected in this step.
+        #
+        # Finally, at the closing step, the array of
+        # ``ArrowStringDescription`` and the layout information
+        # incorporated in ``DiagramGrid`` are combined to produce the
+        # resulting Xy-pic picture.  This part of code lies in
+        # ``_build_xypic_string``.
+
+        if not masked:
+            morphisms_props = grid.morphisms
+        else:
+            morphisms_props = {}
+            for m, props in grid.morphisms.items():
+                if m in masked:
+                    continue
+                morphisms_props[m] = props
+
+        # Build the mapping between objects and their position in the
+        # grid.
+        object_coords = {}
+        for i in range(grid.height):
+            for j in range(grid.width):
+                if grid[i, j]:
+                    object_coords[grid[i, j]] = (i, j)
+
+        morphisms = sorted(morphisms_props,
+                           key=lambda m: XypicDiagramDrawer._morphism_sort_key(
+                               m, object_coords))
+
+        # Build the tuples defining the string representations of
+        # morphisms.
+        morphisms_str_info = {}
+        for morphism in morphisms:
+            string_description = self._process_morphism(
+                diagram, grid, morphism, object_coords, morphisms,
+                morphisms_str_info)
+
+            if self.default_arrow_formatter:
+                self.default_arrow_formatter(string_description)
+
+            for prop in morphisms_props[morphism]:
+                # prop is a Symbol.  TODO: Find out why.
+                if prop.name in self.arrow_formatters:
+                    formatter = self.arrow_formatters[prop.name]
+                    formatter(string_description)
+
+            morphisms_str_info[morphism] = string_description
+
+        # Reposition the labels a bit.
+        self._push_labels_out(morphisms_str_info, grid, object_coords)
+
+        return XypicDiagramDrawer._build_xypic_string(
+            diagram, grid, morphisms, morphisms_str_info, diagram_format)
+
+
+def xypic_draw_diagram(diagram, masked=None, diagram_format="",
+                       groups=None, **hints):
+    r"""
+    Provides a shortcut combining :class:`DiagramGrid` and
+    :class:`XypicDiagramDrawer`.  Returns an Xy-pic presentation of
+    ``diagram``.  The argument ``masked`` is a list of morphisms which
+    will be not be drawn.  The argument ``diagram_format`` is the
+    format string inserted after "\xymatrix".  ``groups`` should be a
+    set of logical groups.  The ``hints`` will be passed directly to
+    the constructor of :class:`DiagramGrid`.
+
+    For more information about the arguments, see the docstrings of
+    :class:`DiagramGrid` and ``XypicDiagramDrawer.draw``.
+
+    Examples
+    ========
+
+    >>> from sympy.categories import Object, NamedMorphism, Diagram
+    >>> from sympy.categories import xypic_draw_diagram
+    >>> A = Object("A")
+    >>> B = Object("B")
+    >>> C = Object("C")
+    >>> f = NamedMorphism(A, B, "f")
+    >>> g = NamedMorphism(B, C, "g")
+    >>> diagram = Diagram([f, g], {g * f: "unique"})
+    >>> print(xypic_draw_diagram(diagram))
+    \xymatrix{
+    A \ar[d]_{g\circ f} \ar[r]^{f} & B \ar[ld]^{g} \\
+    C &
+    }
+
+    See Also
+    ========
+
+    XypicDiagramDrawer, DiagramGrid
+    """
+    grid = DiagramGrid(diagram, groups, **hints)
+    drawer = XypicDiagramDrawer()
+    return drawer.draw(diagram, grid, masked, diagram_format)
+
+
+@doctest_depends_on(exe=('latex', 'dvipng'), modules=('pyglet',))
+def preview_diagram(diagram, masked=None, diagram_format="", groups=None,
+                    output='png', viewer=None, euler=True, **hints):
+    """
+    Combines the functionality of ``xypic_draw_diagram`` and
+    ``sympy.printing.preview``.  The arguments ``masked``,
+    ``diagram_format``, ``groups``, and ``hints`` are passed to
+    ``xypic_draw_diagram``, while ``output``, ``viewer, and ``euler``
+    are passed to ``preview``.
+
+    Examples
+    ========
+
+    >>> from sympy.categories import Object, NamedMorphism, Diagram
+    >>> from sympy.categories import preview_diagram
+    >>> A = Object("A")
+    >>> B = Object("B")
+    >>> C = Object("C")
+    >>> f = NamedMorphism(A, B, "f")
+    >>> g = NamedMorphism(B, C, "g")
+    >>> d = Diagram([f, g], {g * f: "unique"})
+    >>> preview_diagram(d)
+
+    See Also
+    ========
+
+    XypicDiagramDrawer
+    """
+    from sympy.printing import preview
+    latex_output = xypic_draw_diagram(diagram, masked, diagram_format,
+                                      groups, **hints)
+    preview(latex_output, output, viewer, euler, ("xypic",))

venv/lib/python3.10/site-packages/sympy/categories/tests/test_baseclasses.py

@@ -0,0 +1,209 @@
+from sympy.categories import (Object, Morphism, IdentityMorphism,
+                              NamedMorphism, CompositeMorphism,
+                              Diagram, Category)
+from sympy.categories.baseclasses import Class
+from sympy.testing.pytest import raises
+from sympy.core.containers import (Dict, Tuple)
+from sympy.sets import EmptySet
+from sympy.sets.sets import FiniteSet
+
+
+def test_morphisms():
+    A = Object("A")
+    B = Object("B")
+    C = Object("C")
+    D = Object("D")
+
+    # Test the base morphism.
+    f = NamedMorphism(A, B, "f")
+    assert f.domain == A
+    assert f.codomain == B
+    assert f == NamedMorphism(A, B, "f")
+
+    # Test identities.
+    id_A = IdentityMorphism(A)
+    id_B = IdentityMorphism(B)
+    assert id_A.domain == A
+    assert id_A.codomain == A
+    assert id_A == IdentityMorphism(A)
+    assert id_A != id_B
+
+    # Test named morphisms.
+    g = NamedMorphism(B, C, "g")
+    assert g.name == "g"
+    assert g != f
+    assert g == NamedMorphism(B, C, "g")
+    assert g != NamedMorphism(B, C, "f")
+
+    # Test composite morphisms.
+    assert f == CompositeMorphism(f)
+
+    k = g.compose(f)
+    assert k.domain == A
+    assert k.codomain == C
+    assert k.components == Tuple(f, g)
+    assert g * f == k
+    assert CompositeMorphism(f, g) == k
+
+    assert CompositeMorphism(g * f) == g * f
+
+    # Test the associativity of composition.
+    h = NamedMorphism(C, D, "h")
+
+    p = h * g
+    u = h * g * f
+
+    assert h * k == u
+    assert p * f == u
+    assert CompositeMorphism(f, g, h) == u
+
+    # Test flattening.
+    u2 = u.flatten("u")
+    assert isinstance(u2, NamedMorphism)
+    assert u2.name == "u"
+    assert u2.domain == A
+    assert u2.codomain == D
+
+    # Test identities.
+    assert f * id_A == f
+    assert id_B * f == f
+    assert id_A * id_A == id_A
+    assert CompositeMorphism(id_A) == id_A
+
+    # Test bad compositions.
+    raises(ValueError, lambda: f * g)
+
+    raises(TypeError, lambda: f.compose(None))
+    raises(TypeError, lambda: id_A.compose(None))
+    raises(TypeError, lambda: f * None)
+    raises(TypeError, lambda: id_A * None)
+
+    raises(TypeError, lambda: CompositeMorphism(f, None, 1))
+
+    raises(ValueError, lambda: NamedMorphism(A, B, ""))
+    raises(NotImplementedError, lambda: Morphism(A, B))
+
+
+def test_diagram():
+    A = Object("A")
+    B = Object("B")
+    C = Object("C")
+
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(B, C, "g")
+    id_A = IdentityMorphism(A)
+    id_B = IdentityMorphism(B)
+
+    empty = EmptySet
+
+    # Test the addition of identities.
+    d1 = Diagram([f])
+
+    assert d1.objects == FiniteSet(A, B)
+    assert d1.hom(A, B) == (FiniteSet(f), empty)
+    assert d1.hom(A, A) == (FiniteSet(id_A), empty)
+    assert d1.hom(B, B) == (FiniteSet(id_B), empty)
+
+    assert d1 == Diagram([id_A, f])
+    assert d1 == Diagram([f, f])
+
+    # Test the addition of composites.
+    d2 = Diagram([f, g])
+    homAC = d2.hom(A, C)[0]
+
+    assert d2.objects == FiniteSet(A, B, C)
+    assert g * f in d2.premises.keys()
+    assert homAC == FiniteSet(g * f)
+
+    # Test equality, inequality and hash.
+    d11 = Diagram([f])
+
+    assert d1 == d11
+    assert d1 != d2
+    assert hash(d1) == hash(d11)
+
+    d11 = Diagram({f: "unique"})
+    assert d1 != d11
+
+    # Make sure that (re-)adding composites (with new properties)
+    # works as expected.
+    d = Diagram([f, g], {g * f: "unique"})
+    assert d.conclusions == Dict({g * f: FiniteSet("unique")})
+
+    # Check the hom-sets when there are premises and conclusions.
+    assert d.hom(A, C) == (FiniteSet(g * f), FiniteSet(g * f))
+    d = Diagram([f, g], [g * f])
+    assert d.hom(A, C) == (FiniteSet(g * f), FiniteSet(g * f))
+
+    # Check how the properties of composite morphisms are computed.
+    d = Diagram({f: ["unique", "isomorphism"], g: "unique"})
+    assert d.premises[g * f] == FiniteSet("unique")
+
+    # Check that conclusion morphisms with new objects are not allowed.
+    d = Diagram([f], [g])
+    assert d.conclusions == Dict({})
+
+    # Test an empty diagram.
+    d = Diagram()
+    assert d.premises == Dict({})
+    assert d.conclusions == Dict({})
+    assert d.objects == empty
+
+    # Check a SymPy Dict object.
+    d = Diagram(Dict({f: FiniteSet("unique", "isomorphism"), g: "unique"}))
+    assert d.premises[g * f] == FiniteSet("unique")
+
+    # Check the addition of components of composite morphisms.
+    d = Diagram([g * f])
+    assert f in d.premises
+    assert g in d.premises
+
+    # Check subdiagrams.
+    d = Diagram([f, g], {g * f: "unique"})
+
+    d1 = Diagram([f])
+    assert d.is_subdiagram(d1)
+    assert not d1.is_subdiagram(d)
+
+    d = Diagram([NamedMorphism(B, A, "f'")])
+    assert not d.is_subdiagram(d1)
+    assert not d1.is_subdiagram(d)
+
+    d1 = Diagram([f, g], {g * f: ["unique", "something"]})
+    assert not d.is_subdiagram(d1)
+    assert not d1.is_subdiagram(d)
+
+    d = Diagram({f: "blooh"})
+    d1 = Diagram({f: "bleeh"})
+    assert not d.is_subdiagram(d1)
+    assert not d1.is_subdiagram(d)
+
+    d = Diagram([f, g], {f: "unique", g * f: "veryunique"})
+    d1 = d.subdiagram_from_objects(FiniteSet(A, B))
+    assert d1 == Diagram([f], {f: "unique"})
+    raises(ValueError, lambda: d.subdiagram_from_objects(FiniteSet(A,
+           Object("D"))))
+
+    raises(ValueError, lambda: Diagram({IdentityMorphism(A): "unique"}))
+
+
+def test_category():
+    A = Object("A")
+    B = Object("B")
+    C = Object("C")
+
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(B, C, "g")
+
+    d1 = Diagram([f, g])
+    d2 = Diagram([f])
+
+    objects = d1.objects | d2.objects
+
+    K = Category("K", objects, commutative_diagrams=[d1, d2])
+
+    assert K.name == "K"
+    assert K.objects == Class(objects)
+    assert K.commutative_diagrams == FiniteSet(d1, d2)
+
+    raises(ValueError, lambda: Category(""))

venv/lib/python3.10/site-packages/sympy/categories/tests/test_drawing.py

@@ -0,0 +1,919 @@
+from sympy.categories.diagram_drawing import _GrowableGrid, ArrowStringDescription
+from sympy.categories import (DiagramGrid, Object, NamedMorphism,
+                              Diagram, XypicDiagramDrawer, xypic_draw_diagram)
+from sympy.sets.sets import FiniteSet
+
+
+def test_GrowableGrid():
+    grid = _GrowableGrid(1, 2)
+
+    # Check dimensions.
+    assert grid.width == 1
+    assert grid.height == 2
+
+    # Check initialization of elements.
+    assert grid[0, 0] is None
+    assert grid[1, 0] is None
+
+    # Check assignment to elements.
+    grid[0, 0] = 1
+    grid[1, 0] = "two"
+
+    assert grid[0, 0] == 1
+    assert grid[1, 0] == "two"
+
+    # Check appending a row.
+    grid.append_row()
+
+    assert grid.width == 1
+    assert grid.height == 3
+
+    assert grid[0, 0] == 1
+    assert grid[1, 0] == "two"
+    assert grid[2, 0] is None
+
+    # Check appending a column.
+    grid.append_column()
+    assert grid.width == 2
+    assert grid.height == 3
+
+    assert grid[0, 0] == 1
+    assert grid[1, 0] == "two"
+    assert grid[2, 0] is None
+
+    assert grid[0, 1] is None
+    assert grid[1, 1] is None
+    assert grid[2, 1] is None
+
+    grid = _GrowableGrid(1, 2)
+    grid[0, 0] = 1
+    grid[1, 0] = "two"
+
+    # Check prepending a row.
+    grid.prepend_row()
+    assert grid.width == 1
+    assert grid.height == 3
+
+    assert grid[0, 0] is None
+    assert grid[1, 0] == 1
+    assert grid[2, 0] == "two"
+
+    # Check prepending a column.
+    grid.prepend_column()
+    assert grid.width == 2
+    assert grid.height == 3
+
+    assert grid[0, 0] is None
+    assert grid[1, 0] is None
+    assert grid[2, 0] is None
+
+    assert grid[0, 1] is None
+    assert grid[1, 1] == 1
+    assert grid[2, 1] == "two"
+
+
+def test_DiagramGrid():
+    # Set up some objects and morphisms.
+    A = Object("A")
+    B = Object("B")
+    C = Object("C")
+    D = Object("D")
+    E = Object("E")
+
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(B, C, "g")
+    h = NamedMorphism(D, A, "h")
+    k = NamedMorphism(D, B, "k")
+
+    # A one-morphism diagram.
+    d = Diagram([f])
+    grid = DiagramGrid(d)
+
+    assert grid.width == 2
+    assert grid.height == 1
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+    assert grid.morphisms == {f: FiniteSet()}
+
+    # A triangle.
+    d = Diagram([f, g], {g * f: "unique"})
+    grid = DiagramGrid(d)
+
+    assert grid.width == 2
+    assert grid.height == 2
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+    assert grid[1, 0] == C
+    assert grid[1, 1] is None
+    assert grid.morphisms == {f: FiniteSet(), g: FiniteSet(),
+                              g * f: FiniteSet("unique")}
+
+    # A triangle with a "loop" morphism.
+    l_A = NamedMorphism(A, A, "l_A")
+    d = Diagram([f, g, l_A])
+    grid = DiagramGrid(d)
+
+    assert grid.width == 2
+    assert grid.height == 2
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+    assert grid[1, 0] is None
+    assert grid[1, 1] == C
+    assert grid.morphisms == {f: FiniteSet(), g: FiniteSet(), l_A: FiniteSet()}
+
+    # A simple diagram.
+    d = Diagram([f, g, h, k])
+    grid = DiagramGrid(d)
+
+    assert grid.width == 3
+    assert grid.height == 2
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+    assert grid[0, 2] == D
+    assert grid[1, 0] is None
+    assert grid[1, 1] == C
+    assert grid[1, 2] is None
+    assert grid.morphisms == {f: FiniteSet(), g: FiniteSet(), h: FiniteSet(),
+                              k: FiniteSet()}
+
+    assert str(grid) == '[[Object("A"), Object("B"), Object("D")], ' \
+        '[None, Object("C"), None]]'
+
+    # A chain of morphisms.
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(B, C, "g")
+    h = NamedMorphism(C, D, "h")
+    k = NamedMorphism(D, E, "k")
+    d = Diagram([f, g, h, k])
+    grid = DiagramGrid(d)
+
+    assert grid.width == 3
+    assert grid.height == 3
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+    assert grid[0, 2] is None
+    assert grid[1, 0] is None
+    assert grid[1, 1] == C
+    assert grid[1, 2] == D
+    assert grid[2, 0] is None
+    assert grid[2, 1] is None
+    assert grid[2, 2] == E
+    assert grid.morphisms == {f: FiniteSet(), g: FiniteSet(), h: FiniteSet(),
+                              k: FiniteSet()}
+
+    # A square.
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(B, D, "g")
+    h = NamedMorphism(A, C, "h")
+    k = NamedMorphism(C, D, "k")
+    d = Diagram([f, g, h, k])
+    grid = DiagramGrid(d)
+
+    assert grid.width == 2
+    assert grid.height == 2
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+    assert grid[1, 0] == C
+    assert grid[1, 1] == D
+    assert grid.morphisms == {f: FiniteSet(), g: FiniteSet(), h: FiniteSet(),
+                              k: FiniteSet()}
+
+    # A strange diagram which resulted from a typo when creating a
+    # test for five lemma, but which allowed to stop one extra problem
+    # in the algorithm.
+    A = Object("A")
+    B = Object("B")
+    C = Object("C")
+    D = Object("D")
+    E = Object("E")
+    A_ = Object("A'")
+    B_ = Object("B'")
+    C_ = Object("C'")
+    D_ = Object("D'")
+    E_ = Object("E'")
+
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(B, C, "g")
+    h = NamedMorphism(C, D, "h")
+    i = NamedMorphism(D, E, "i")
+
+    # These 4 morphisms should be between primed objects.
+    j = NamedMorphism(A, B, "j")
+    k = NamedMorphism(B, C, "k")
+    l = NamedMorphism(C, D, "l")
+    m = NamedMorphism(D, E, "m")
+
+    o = NamedMorphism(A, A_, "o")
+    p = NamedMorphism(B, B_, "p")
+    q = NamedMorphism(C, C_, "q")
+    r = NamedMorphism(D, D_, "r")
+    s = NamedMorphism(E, E_, "s")
+
+    d = Diagram([f, g, h, i, j, k, l, m, o, p, q, r, s])
+    grid = DiagramGrid(d)
+
+    assert grid.width == 3
+    assert grid.height == 4
+    assert grid[0, 0] is None
+    assert grid[0, 1] == A
+    assert grid[0, 2] == A_
+    assert grid[1, 0] == C
+    assert grid[1, 1] == B
+    assert grid[1, 2] == B_
+    assert grid[2, 0] == C_
+    assert grid[2, 1] == D
+    assert grid[2, 2] == D_
+    assert grid[3, 0] is None
+    assert grid[3, 1] == E
+    assert grid[3, 2] == E_
+
+    morphisms = {}
+    for m in [f, g, h, i, j, k, l, m, o, p, q, r, s]:
+        morphisms[m] = FiniteSet()
+    assert grid.morphisms == morphisms
+
+    # A cube.
+    A1 = Object("A1")
+    A2 = Object("A2")
+    A3 = Object("A3")
+    A4 = Object("A4")
+    A5 = Object("A5")
+    A6 = Object("A6")
+    A7 = Object("A7")
+    A8 = Object("A8")
+
+    # The top face of the cube.
+    f1 = NamedMorphism(A1, A2, "f1")
+    f2 = NamedMorphism(A1, A3, "f2")
+    f3 = NamedMorphism(A2, A4, "f3")
+    f4 = NamedMorphism(A3, A4, "f3")
+
+    # The bottom face of the cube.
+    f5 = NamedMorphism(A5, A6, "f5")
+    f6 = NamedMorphism(A5, A7, "f6")
+    f7 = NamedMorphism(A6, A8, "f7")
+    f8 = NamedMorphism(A7, A8, "f8")
+
+    # The remaining morphisms.
+    f9 = NamedMorphism(A1, A5, "f9")
+    f10 = NamedMorphism(A2, A6, "f10")
+    f11 = NamedMorphism(A3, A7, "f11")
+    f12 = NamedMorphism(A4, A8, "f11")
+
+    d = Diagram([f1, f2, f3, f4, f5, f6, f7, f8, f9, f10, f11, f12])
+    grid = DiagramGrid(d)
+
+    assert grid.width == 4
+    assert grid.height == 3
+    assert grid[0, 0] is None
+    assert grid[0, 1] == A5
+    assert grid[0, 2] == A6
+    assert grid[0, 3] is None
+    assert grid[1, 0] is None
+    assert grid[1, 1] == A1
+    assert grid[1, 2] == A2
+    assert grid[1, 3] is None
+    assert grid[2, 0] == A7
+    assert grid[2, 1] == A3
+    assert grid[2, 2] == A4
+    assert grid[2, 3] == A8
+
+    morphisms = {}
+    for m in [f1, f2, f3, f4, f5, f6, f7, f8, f9, f10, f11, f12]:
+        morphisms[m] = FiniteSet()
+    assert grid.morphisms == morphisms
+
+    # A line diagram.
+    A = Object("A")
+    B = Object("B")
+    C = Object("C")
+    D = Object("D")
+    E = Object("E")
+
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(B, C, "g")
+    h = NamedMorphism(C, D, "h")
+    i = NamedMorphism(D, E, "i")
+    d = Diagram([f, g, h, i])
+    grid = DiagramGrid(d, layout="sequential")
+
+    assert grid.width == 5
+    assert grid.height == 1
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+    assert grid[0, 2] == C
+    assert grid[0, 3] == D
+    assert grid[0, 4] == E
+    assert grid.morphisms == {f: FiniteSet(), g: FiniteSet(), h: FiniteSet(),
+                              i: FiniteSet()}
+
+    # Test the transposed version.
+    grid = DiagramGrid(d, layout="sequential", transpose=True)
+
+    assert grid.width == 1
+    assert grid.height == 5
+    assert grid[0, 0] == A
+    assert grid[1, 0] == B
+    assert grid[2, 0] == C
+    assert grid[3, 0] == D
+    assert grid[4, 0] == E
+    assert grid.morphisms == {f: FiniteSet(), g: FiniteSet(), h: FiniteSet(),
+                              i: FiniteSet()}
+
+    # A pullback.
+    m1 = NamedMorphism(A, B, "m1")
+    m2 = NamedMorphism(A, C, "m2")
+    s1 = NamedMorphism(B, D, "s1")
+    s2 = NamedMorphism(C, D, "s2")
+    f1 = NamedMorphism(E, B, "f1")
+    f2 = NamedMorphism(E, C, "f2")
+    g = NamedMorphism(E, A, "g")
+
+    d = Diagram([m1, m2, s1, s2, f1, f2], {g: "unique"})
+    grid = DiagramGrid(d)
+
+    assert grid.width == 3
+    assert grid.height == 2
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+    assert grid[0, 2] == E
+    assert grid[1, 0] == C
+    assert grid[1, 1] == D
+    assert grid[1, 2] is None
+
+    morphisms = {g: FiniteSet("unique")}
+    for m in [m1, m2, s1, s2, f1, f2]:
+        morphisms[m] = FiniteSet()
+    assert grid.morphisms == morphisms
+
+    # Test the pullback with sequential layout, just for stress
+    # testing.
+    grid = DiagramGrid(d, layout="sequential")
+
+    assert grid.width == 5
+    assert grid.height == 1
+    assert grid[0, 0] == D
+    assert grid[0, 1] == B
+    assert grid[0, 2] == A
+    assert grid[0, 3] == C
+    assert grid[0, 4] == E
+    assert grid.morphisms == morphisms
+
+    # Test a pullback with object grouping.
+    grid = DiagramGrid(d, groups=FiniteSet(E, FiniteSet(A, B, C, D)))
+
+    assert grid.width == 3
+    assert grid.height == 2
+    assert grid[0, 0] == E
+    assert grid[0, 1] == A
+    assert grid[0, 2] == B
+    assert grid[1, 0] is None
+    assert grid[1, 1] == C
+    assert grid[1, 2] == D
+    assert grid.morphisms == morphisms
+
+    # Five lemma, actually.
+    A = Object("A")
+    B = Object("B")
+    C = Object("C")
+    D = Object("D")
+    E = Object("E")
+    A_ = Object("A'")
+    B_ = Object("B'")
+    C_ = Object("C'")
+    D_ = Object("D'")
+    E_ = Object("E'")
+
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(B, C, "g")
+    h = NamedMorphism(C, D, "h")
+    i = NamedMorphism(D, E, "i")
+
+    j = NamedMorphism(A_, B_, "j")
+    k = NamedMorphism(B_, C_, "k")
+    l = NamedMorphism(C_, D_, "l")
+    m = NamedMorphism(D_, E_, "m")
+
+    o = NamedMorphism(A, A_, "o")
+    p = NamedMorphism(B, B_, "p")
+    q = NamedMorphism(C, C_, "q")
+    r = NamedMorphism(D, D_, "r")
+    s = NamedMorphism(E, E_, "s")
+
+    d = Diagram([f, g, h, i, j, k, l, m, o, p, q, r, s])
+    grid = DiagramGrid(d)
+
+    assert grid.width == 5
+    assert grid.height == 3
+    assert grid[0, 0] is None
+    assert grid[0, 1] == A
+    assert grid[0, 2] == A_
+    assert grid[0, 3] is None
+    assert grid[0, 4] is None
+    assert grid[1, 0] == C
+    assert grid[1, 1] == B
+    assert grid[1, 2] == B_
+    assert grid[1, 3] == C_
+    assert grid[1, 4] is None
+    assert grid[2, 0] == D
+    assert grid[2, 1] == E
+    assert grid[2, 2] is None
+    assert grid[2, 3] == D_
+    assert grid[2, 4] == E_
+
+    morphisms = {}
+    for m in [f, g, h, i, j, k, l, m, o, p, q, r, s]:
+        morphisms[m] = FiniteSet()
+    assert grid.morphisms == morphisms
+
+    # Test the five lemma with object grouping.
+    grid = DiagramGrid(d, FiniteSet(
+        FiniteSet(A, B, C, D, E), FiniteSet(A_, B_, C_, D_, E_)))
+
+    assert grid.width == 6
+    assert grid.height == 3
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+    assert grid[0, 2] is None
+    assert grid[0, 3] == A_
+    assert grid[0, 4] == B_
+    assert grid[0, 5] is None
+    assert grid[1, 0] is None
+    assert grid[1, 1] == C
+    assert grid[1, 2] == D
+    assert grid[1, 3] is None
+    assert grid[1, 4] == C_
+    assert grid[1, 5] == D_
+    assert grid[2, 0] is None
+    assert grid[2, 1] is None
+    assert grid[2, 2] == E
+    assert grid[2, 3] is None
+    assert grid[2, 4] is None
+    assert grid[2, 5] == E_
+    assert grid.morphisms == morphisms
+
+    # Test the five lemma with object grouping, but mixing containers
+    # to represent groups.
+    grid = DiagramGrid(d, [(A, B, C, D, E), {A_, B_, C_, D_, E_}])
+
+    assert grid.width == 6
+    assert grid.height == 3
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+    assert grid[0, 2] is None
+    assert grid[0, 3] == A_
+    assert grid[0, 4] == B_
+    assert grid[0, 5] is None
+    assert grid[1, 0] is None
+    assert grid[1, 1] == C
+    assert grid[1, 2] == D
+    assert grid[1, 3] is None
+    assert grid[1, 4] == C_
+    assert grid[1, 5] == D_
+    assert grid[2, 0] is None
+    assert grid[2, 1] is None
+    assert grid[2, 2] == E
+    assert grid[2, 3] is None
+    assert grid[2, 4] is None
+    assert grid[2, 5] == E_
+    assert grid.morphisms == morphisms
+
+    # Test the five lemma with object grouping and hints.
+    grid = DiagramGrid(d, {
+        FiniteSet(A, B, C, D, E): {"layout": "sequential",
+                                   "transpose": True},
+        FiniteSet(A_, B_, C_, D_, E_): {"layout": "sequential",
+                                        "transpose": True}},
+        transpose=True)
+
+    assert grid.width == 5
+    assert grid.height == 2
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+    assert grid[0, 2] == C
+    assert grid[0, 3] == D
+    assert grid[0, 4] == E
+    assert grid[1, 0] == A_
+    assert grid[1, 1] == B_
+    assert grid[1, 2] == C_
+    assert grid[1, 3] == D_
+    assert grid[1, 4] == E_
+    assert grid.morphisms == morphisms
+
+    # A two-triangle disconnected diagram.
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(B, C, "g")
+    f_ = NamedMorphism(A_, B_, "f")
+    g_ = NamedMorphism(B_, C_, "g")
+    d = Diagram([f, g, f_, g_], {g * f: "unique", g_ * f_: "unique"})
+    grid = DiagramGrid(d)
+
+    assert grid.width == 4
+    assert grid.height == 2
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+    assert grid[0, 2] == A_
+    assert grid[0, 3] == B_
+    assert grid[1, 0] == C
+    assert grid[1, 1] is None
+    assert grid[1, 2] == C_
+    assert grid[1, 3] is None
+    assert grid.morphisms == {f: FiniteSet(), g: FiniteSet(), f_: FiniteSet(),
+                              g_: FiniteSet(), g * f: FiniteSet("unique"),
+                              g_ * f_: FiniteSet("unique")}
+
+    # A two-morphism disconnected diagram.
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(C, D, "g")
+    d = Diagram([f, g])
+    grid = DiagramGrid(d)
+
+    assert grid.width == 4
+    assert grid.height == 1
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+    assert grid[0, 2] == C
+    assert grid[0, 3] == D
+    assert grid.morphisms == {f: FiniteSet(), g: FiniteSet()}
+
+    # Test a one-object diagram.
+    f = NamedMorphism(A, A, "f")
+    d = Diagram([f])
+    grid = DiagramGrid(d)
+
+    assert grid.width == 1
+    assert grid.height == 1
+    assert grid[0, 0] == A
+
+    # Test a two-object disconnected diagram.
+    g = NamedMorphism(B, B, "g")
+    d = Diagram([f, g])
+    grid = DiagramGrid(d)
+
+    assert grid.width == 2
+    assert grid.height == 1
+    assert grid[0, 0] == A
+    assert grid[0, 1] == B
+
+
+def test_DiagramGrid_pseudopod():
+    # Test a diagram in which even growing a pseudopod does not
+    # eventually help.
+    A = Object("A")
+    B = Object("B")
+    C = Object("C")
+    D = Object("D")
+    E = Object("E")
+    F = Object("F")
+    A_ = Object("A'")
+    B_ = Object("B'")
+    C_ = Object("C'")
+    D_ = Object("D'")
+    E_ = Object("E'")
+
+    f1 = NamedMorphism(A, B, "f1")
+    f2 = NamedMorphism(A, C, "f2")
+    f3 = NamedMorphism(A, D, "f3")
+    f4 = NamedMorphism(A, E, "f4")
+    f5 = NamedMorphism(A, A_, "f5")
+    f6 = NamedMorphism(A, B_, "f6")
+    f7 = NamedMorphism(A, C_, "f7")
+    f8 = NamedMorphism(A, D_, "f8")
+    f9 = NamedMorphism(A, E_, "f9")
+    f10 = NamedMorphism(A, F, "f10")
+    d = Diagram([f1, f2, f3, f4, f5, f6, f7, f8, f9, f10])
+    grid = DiagramGrid(d)
+
+    assert grid.width == 5
+    assert grid.height == 3
+    assert grid[0, 0] == E
+    assert grid[0, 1] == C
+    assert grid[0, 2] == C_
+    assert grid[0, 3] == E_
+    assert grid[0, 4] == F
+    assert grid[1, 0] == D
+    assert grid[1, 1] == A
+    assert grid[1, 2] == A_
+    assert grid[1, 3] is None
+    assert grid[1, 4] is None
+    assert grid[2, 0] == D_
+    assert grid[2, 1] == B
+    assert grid[2, 2] == B_
+    assert grid[2, 3] is None
+    assert grid[2, 4] is None
+
+    morphisms = {}
+    for f in [f1, f2, f3, f4, f5, f6, f7, f8, f9, f10]:
+        morphisms[f] = FiniteSet()
+    assert grid.morphisms == morphisms
+
+
+def test_ArrowStringDescription():
+    astr = ArrowStringDescription("cm", "", None, "", "", "d", "r", "_", "f")
+    assert str(astr) == "\\ar[dr]_{f}"
+
+    astr = ArrowStringDescription("cm", "", 12, "", "", "d", "r", "_", "f")
+    assert str(astr) == "\\ar[dr]_{f}"
+
+    astr = ArrowStringDescription("cm", "^", 12, "", "", "d", "r", "_", "f")
+    assert str(astr) == "\\ar@/^12cm/[dr]_{f}"
+
+    astr = ArrowStringDescription("cm", "", 12, "r", "", "d", "r", "_", "f")
+    assert str(astr) == "\\ar[dr]_{f}"
+
+    astr = ArrowStringDescription("cm", "", 12, "r", "u", "d", "r", "_", "f")
+    assert str(astr) == "\\ar@(r,u)[dr]_{f}"
+
+    astr = ArrowStringDescription("cm", "", 12, "r", "u", "d", "r", "_", "f")
+    assert str(astr) == "\\ar@(r,u)[dr]_{f}"
+
+    astr = ArrowStringDescription("cm", "", 12, "r", "u", "d", "r", "_", "f")
+    astr.arrow_style = "{-->}"
+    assert str(astr) == "\\ar@(r,u)@{-->}[dr]_{f}"
+
+    astr = ArrowStringDescription("cm", "_", 12, "", "", "d", "r", "_", "f")
+    astr.arrow_style = "{-->}"
+    assert str(astr) == "\\ar@/_12cm/@{-->}[dr]_{f}"
+
+
+def test_XypicDiagramDrawer_line():
+    # A linear diagram.
+    A = Object("A")
+    B = Object("B")
+    C = Object("C")
+    D = Object("D")
+    E = Object("E")
+
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(B, C, "g")
+    h = NamedMorphism(C, D, "h")
+    i = NamedMorphism(D, E, "i")
+    d = Diagram([f, g, h, i])
+    grid = DiagramGrid(d, layout="sequential")
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar[r]^{f} & B \\ar[r]^{g} & C \\ar[r]^{h} & D \\ar[r]^{i} & E \n" \
+        "}\n"
+
+    # The same diagram, transposed.
+    grid = DiagramGrid(d, layout="sequential", transpose=True)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar[d]^{f} \\\\\n" \
+        "B \\ar[d]^{g} \\\\\n" \
+        "C \\ar[d]^{h} \\\\\n" \
+        "D \\ar[d]^{i} \\\\\n" \
+        "E \n" \
+        "}\n"
+
+
+def test_XypicDiagramDrawer_triangle():
+    # A triangle diagram.
+    A = Object("A")
+    B = Object("B")
+    C = Object("C")
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(B, C, "g")
+
+    d = Diagram([f, g], {g * f: "unique"})
+    grid = DiagramGrid(d)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar[d]_{g\\circ f} \\ar[r]^{f} & B \\ar[ld]^{g} \\\\\n" \
+        "C & \n" \
+        "}\n"
+
+    # The same diagram, transposed.
+    grid = DiagramGrid(d, transpose=True)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar[r]^{g\\circ f} \\ar[d]_{f} & C \\\\\n" \
+        "B \\ar[ru]_{g} & \n" \
+        "}\n"
+
+    # The same diagram, with a masked morphism.
+    assert drawer.draw(d, grid, masked=[g]) == "\\xymatrix{\n" \
+        "A \\ar[r]^{g\\circ f} \\ar[d]_{f} & C \\\\\n" \
+        "B & \n" \
+        "}\n"
+
+    # The same diagram with a formatter for "unique".
+    def formatter(astr):
+        astr.label = "\\exists !" + astr.label
+        astr.arrow_style = "{-->}"
+
+    drawer.arrow_formatters["unique"] = formatter
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar@{-->}[r]^{\\exists !g\\circ f} \\ar[d]_{f} & C \\\\\n" \
+        "B \\ar[ru]_{g} & \n" \
+        "}\n"
+
+    # The same diagram with a default formatter.
+    def default_formatter(astr):
+        astr.label_displacement = "(0.45)"
+
+    drawer.default_arrow_formatter = default_formatter
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar@{-->}[r]^(0.45){\\exists !g\\circ f} \\ar[d]_(0.45){f} & C \\\\\n" \
+        "B \\ar[ru]_(0.45){g} & \n" \
+        "}\n"
+
+    # A triangle diagram with a lot of morphisms between the same
+    # objects.
+    f1 = NamedMorphism(B, A, "f1")
+    f2 = NamedMorphism(A, B, "f2")
+    g1 = NamedMorphism(C, B, "g1")
+    g2 = NamedMorphism(B, C, "g2")
+    d = Diagram([f, f1, f2, g, g1, g2], {f1 * g1: "unique", g2 * f2: "unique"})
+
+    grid = DiagramGrid(d, transpose=True)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid, masked=[f1*g1*g2*f2, g2*f2*f1*g1]) == \
+        "\\xymatrix{\n" \
+        "A \\ar[r]^{g_{2}\\circ f_{2}} \\ar[d]_{f} \\ar@/^3mm/[d]^{f_{2}} " \
+        "& C \\ar@/^3mm/[l]^{f_{1}\\circ g_{1}} \\ar@/^3mm/[ld]^{g_{1}} \\\\\n" \
+        "B \\ar@/^3mm/[u]^{f_{1}} \\ar[ru]_{g} \\ar@/^3mm/[ru]^{g_{2}} & \n" \
+        "}\n"
+
+
+def test_XypicDiagramDrawer_cube():
+    # A cube diagram.
+    A1 = Object("A1")
+    A2 = Object("A2")
+    A3 = Object("A3")
+    A4 = Object("A4")
+    A5 = Object("A5")
+    A6 = Object("A6")
+    A7 = Object("A7")
+    A8 = Object("A8")
+
+    # The top face of the cube.
+    f1 = NamedMorphism(A1, A2, "f1")
+    f2 = NamedMorphism(A1, A3, "f2")
+    f3 = NamedMorphism(A2, A4, "f3")
+    f4 = NamedMorphism(A3, A4, "f3")
+
+    # The bottom face of the cube.
+    f5 = NamedMorphism(A5, A6, "f5")
+    f6 = NamedMorphism(A5, A7, "f6")
+    f7 = NamedMorphism(A6, A8, "f7")
+    f8 = NamedMorphism(A7, A8, "f8")
+
+    # The remaining morphisms.
+    f9 = NamedMorphism(A1, A5, "f9")
+    f10 = NamedMorphism(A2, A6, "f10")
+    f11 = NamedMorphism(A3, A7, "f11")
+    f12 = NamedMorphism(A4, A8, "f11")
+
+    d = Diagram([f1, f2, f3, f4, f5, f6, f7, f8, f9, f10, f11, f12])
+    grid = DiagramGrid(d)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "& A_{5} \\ar[r]^{f_{5}} \\ar[ldd]_{f_{6}} & A_{6} \\ar[rdd]^{f_{7}} " \
+        "& \\\\\n" \
+        "& A_{1} \\ar[r]^{f_{1}} \\ar[d]^{f_{2}} \\ar[u]^{f_{9}} & A_{2} " \
+        "\\ar[d]^{f_{3}} \\ar[u]_{f_{10}} & \\\\\n" \
+        "A_{7} \\ar@/_3mm/[rrr]_{f_{8}} & A_{3} \\ar[r]^{f_{3}} \\ar[l]_{f_{11}} " \
+        "& A_{4} \\ar[r]^{f_{11}} & A_{8} \n" \
+        "}\n"
+
+    # The same diagram, transposed.
+    grid = DiagramGrid(d, transpose=True)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "& & A_{7} \\ar@/^3mm/[ddd]^{f_{8}} \\\\\n" \
+        "A_{5} \\ar[d]_{f_{5}} \\ar[rru]^{f_{6}} & A_{1} \\ar[d]^{f_{1}} " \
+        "\\ar[r]^{f_{2}} \\ar[l]^{f_{9}} & A_{3} \\ar[d]_{f_{3}} " \
+        "\\ar[u]^{f_{11}} \\\\\n" \
+        "A_{6} \\ar[rrd]_{f_{7}} & A_{2} \\ar[r]^{f_{3}} \\ar[l]^{f_{10}} " \
+        "& A_{4} \\ar[d]_{f_{11}} \\\\\n" \
+        "& & A_{8} \n" \
+        "}\n"
+
+
+def test_XypicDiagramDrawer_curved_and_loops():
+    # A simple diagram, with a curved arrow.
+    A = Object("A")
+    B = Object("B")
+    C = Object("C")
+    D = Object("D")
+
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(B, C, "g")
+    h = NamedMorphism(D, A, "h")
+    k = NamedMorphism(D, B, "k")
+    d = Diagram([f, g, h, k])
+    grid = DiagramGrid(d)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar[r]_{f} & B \\ar[d]^{g} & D \\ar[l]^{k} \\ar@/_3mm/[ll]_{h} \\\\\n" \
+        "& C & \n" \
+        "}\n"
+
+    # The same diagram, transposed.
+    grid = DiagramGrid(d, transpose=True)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar[d]^{f} & \\\\\n" \
+        "B \\ar[r]^{g} & C \\\\\n" \
+        "D \\ar[u]_{k} \\ar@/^3mm/[uu]^{h} & \n" \
+        "}\n"
+
+    # The same diagram, larger and rotated.
+    assert drawer.draw(d, grid, diagram_format="@+1cm@dr") == \
+        "\\xymatrix@+1cm@dr{\n" \
+        "A \\ar[d]^{f} & \\\\\n" \
+        "B \\ar[r]^{g} & C \\\\\n" \
+        "D \\ar[u]_{k} \\ar@/^3mm/[uu]^{h} & \n" \
+        "}\n"
+
+    # A simple diagram with three curved arrows.
+    h1 = NamedMorphism(D, A, "h1")
+    h2 = NamedMorphism(A, D, "h2")
+    k = NamedMorphism(D, B, "k")
+    d = Diagram([f, g, h, k, h1, h2])
+    grid = DiagramGrid(d)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar[r]_{f} \\ar@/^3mm/[rr]^{h_{2}} & B \\ar[d]^{g} & D \\ar[l]^{k} " \
+        "\\ar@/_7mm/[ll]_{h} \\ar@/_11mm/[ll]_{h_{1}} \\\\\n" \
+        "& C & \n" \
+        "}\n"
+
+    # The same diagram, transposed.
+    grid = DiagramGrid(d, transpose=True)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar[d]^{f} \\ar@/_3mm/[dd]_{h_{2}} & \\\\\n" \
+        "B \\ar[r]^{g} & C \\\\\n" \
+        "D \\ar[u]_{k} \\ar@/^7mm/[uu]^{h} \\ar@/^11mm/[uu]^{h_{1}} & \n" \
+        "}\n"
+
+    # The same diagram, with "loop" morphisms.
+    l_A = NamedMorphism(A, A, "l_A")
+    l_D = NamedMorphism(D, D, "l_D")
+    l_C = NamedMorphism(C, C, "l_C")
+    d = Diagram([f, g, h, k, h1, h2, l_A, l_D, l_C])
+    grid = DiagramGrid(d)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar[r]_{f} \\ar@/^3mm/[rr]^{h_{2}} \\ar@(u,l)[]^{l_{A}} " \
+        "& B \\ar[d]^{g} & D \\ar[l]^{k} \\ar@/_7mm/[ll]_{h} " \
+        "\\ar@/_11mm/[ll]_{h_{1}} \\ar@(r,u)[]^{l_{D}} \\\\\n" \
+        "& C \\ar@(l,d)[]^{l_{C}} & \n" \
+        "}\n"
+
+    # The same diagram with "loop" morphisms, transposed.
+    grid = DiagramGrid(d, transpose=True)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar[d]^{f} \\ar@/_3mm/[dd]_{h_{2}} \\ar@(r,u)[]^{l_{A}} & \\\\\n" \
+        "B \\ar[r]^{g} & C \\ar@(r,u)[]^{l_{C}} \\\\\n" \
+        "D \\ar[u]_{k} \\ar@/^7mm/[uu]^{h} \\ar@/^11mm/[uu]^{h_{1}} " \
+        "\\ar@(l,d)[]^{l_{D}} & \n" \
+        "}\n"
+
+    # The same diagram with two "loop" morphisms per object.
+    l_A_ = NamedMorphism(A, A, "n_A")
+    l_D_ = NamedMorphism(D, D, "n_D")
+    l_C_ = NamedMorphism(C, C, "n_C")
+    d = Diagram([f, g, h, k, h1, h2, l_A, l_D, l_C, l_A_, l_D_, l_C_])
+    grid = DiagramGrid(d)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar[r]_{f} \\ar@/^3mm/[rr]^{h_{2}} \\ar@(u,l)[]^{l_{A}} " \
+        "\\ar@/^3mm/@(l,d)[]^{n_{A}} & B \\ar[d]^{g} & D \\ar[l]^{k} " \
+        "\\ar@/_7mm/[ll]_{h} \\ar@/_11mm/[ll]_{h_{1}} \\ar@(r,u)[]^{l_{D}} " \
+        "\\ar@/^3mm/@(d,r)[]^{n_{D}} \\\\\n" \
+        "& C \\ar@(l,d)[]^{l_{C}} \\ar@/^3mm/@(d,r)[]^{n_{C}} & \n" \
+        "}\n"
+
+    # The same diagram with two "loop" morphisms per object, transposed.
+    grid = DiagramGrid(d, transpose=True)
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == "\\xymatrix{\n" \
+        "A \\ar[d]^{f} \\ar@/_3mm/[dd]_{h_{2}} \\ar@(r,u)[]^{l_{A}} " \
+        "\\ar@/^3mm/@(u,l)[]^{n_{A}} & \\\\\n" \
+        "B \\ar[r]^{g} & C \\ar@(r,u)[]^{l_{C}} \\ar@/^3mm/@(d,r)[]^{n_{C}} \\\\\n" \
+        "D \\ar[u]_{k} \\ar@/^7mm/[uu]^{h} \\ar@/^11mm/[uu]^{h_{1}} " \
+        "\\ar@(l,d)[]^{l_{D}} \\ar@/^3mm/@(d,r)[]^{n_{D}} & \n" \
+        "}\n"
+
+
+def test_xypic_draw_diagram():
+    # A linear diagram.
+    A = Object("A")
+    B = Object("B")
+    C = Object("C")
+    D = Object("D")
+    E = Object("E")
+
+    f = NamedMorphism(A, B, "f")
+    g = NamedMorphism(B, C, "g")
+    h = NamedMorphism(C, D, "h")
+    i = NamedMorphism(D, E, "i")
+    d = Diagram([f, g, h, i])
+
+    grid = DiagramGrid(d, layout="sequential")
+    drawer = XypicDiagramDrawer()
+    assert drawer.draw(d, grid) == xypic_draw_diagram(d, layout="sequential")

venv/lib/python3.10/site-packages/sympy/crypto/__init__.py

@@ -0,0 +1,35 @@
+from sympy.crypto.crypto import (cycle_list,
+        encipher_shift, encipher_affine, encipher_substitution,
+        check_and_join, encipher_vigenere, decipher_vigenere, bifid5_square,
+        bifid6_square, encipher_hill, decipher_hill,
+        encipher_bifid5, encipher_bifid6, decipher_bifid5,
+        decipher_bifid6, encipher_kid_rsa, decipher_kid_rsa,
+        kid_rsa_private_key, kid_rsa_public_key, decipher_rsa, rsa_private_key,
+        rsa_public_key, encipher_rsa, lfsr_connection_polynomial,
+        lfsr_autocorrelation, lfsr_sequence, encode_morse, decode_morse,
+        elgamal_private_key, elgamal_public_key, decipher_elgamal,
+        encipher_elgamal, dh_private_key, dh_public_key, dh_shared_key,
+        padded_key, encipher_bifid, decipher_bifid, bifid_square, bifid5,
+        bifid6, bifid10, decipher_gm, encipher_gm, gm_public_key,
+        gm_private_key, bg_private_key, bg_public_key, encipher_bg, decipher_bg,
+        encipher_rot13, decipher_rot13, encipher_atbash, decipher_atbash,
+        encipher_railfence, decipher_railfence)
+
+__all__ = [
+    'cycle_list', 'encipher_shift', 'encipher_affine',
+    'encipher_substitution', 'check_and_join', 'encipher_vigenere',
+    'decipher_vigenere', 'bifid5_square', 'bifid6_square', 'encipher_hill',
+    'decipher_hill', 'encipher_bifid5', 'encipher_bifid6', 'decipher_bifid5',
+    'decipher_bifid6', 'encipher_kid_rsa', 'decipher_kid_rsa',
+    'kid_rsa_private_key', 'kid_rsa_public_key', 'decipher_rsa',
+    'rsa_private_key', 'rsa_public_key', 'encipher_rsa',
+    'lfsr_connection_polynomial', 'lfsr_autocorrelation', 'lfsr_sequence',
+    'encode_morse', 'decode_morse', 'elgamal_private_key',
+    'elgamal_public_key', 'decipher_elgamal', 'encipher_elgamal',
+    'dh_private_key', 'dh_public_key', 'dh_shared_key', 'padded_key',
+    'encipher_bifid', 'decipher_bifid', 'bifid_square', 'bifid5', 'bifid6',
+    'bifid10', 'decipher_gm', 'encipher_gm', 'gm_public_key',
+    'gm_private_key', 'bg_private_key', 'bg_public_key', 'encipher_bg',
+    'decipher_bg', 'encipher_rot13', 'decipher_rot13', 'encipher_atbash',
+    'decipher_atbash', 'encipher_railfence', 'decipher_railfence',
+]

venv/lib/python3.10/site-packages/sympy/crypto/crypto.py

@@ -0,0 +1,3360 @@
+"""
+This file contains some classical ciphers and routines
+implementing a linear-feedback shift register (LFSR)
+and the Diffie-Hellman key exchange.
+
+.. warning::
+
+   This module is intended for educational purposes only. Do not use the
+   functions in this module for real cryptographic applications. If you wish
+   to encrypt real data, we recommend using something like the `cryptography
+   <https://cryptography.io/en/latest/>`_ module.
+
+"""
+
+from string import whitespace, ascii_uppercase as uppercase, printable
+from functools import reduce
+import warnings
+
+from itertools import cycle
+
+from sympy.core import Symbol
+from sympy.core.numbers import igcdex, mod_inverse, igcd, Rational
+from sympy.core.random import _randrange, _randint
+from sympy.matrices import Matrix
+from sympy.ntheory import isprime, primitive_root, factorint
+from sympy.ntheory import totient as _euler
+from sympy.ntheory import reduced_totient as _carmichael
+from sympy.ntheory.generate import nextprime
+from sympy.ntheory.modular import crt
+from sympy.polys.domains import FF
+from sympy.polys.polytools import gcd, Poly
+from sympy.utilities.misc import as_int, filldedent, translate
+from sympy.utilities.iterables import uniq, multiset
+
+
+class NonInvertibleCipherWarning(RuntimeWarning):
+    """A warning raised if the cipher is not invertible."""
+    def __init__(self, msg):
+        self.fullMessage = msg
+
+    def __str__(self):
+        return '\n\t' + self.fullMessage
+
+    def warn(self, stacklevel=3):
+        warnings.warn(self, stacklevel=stacklevel)
+
+
+def AZ(s=None):
+    """Return the letters of ``s`` in uppercase. In case more than
+    one string is passed, each of them will be processed and a list
+    of upper case strings will be returned.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import AZ
+    >>> AZ('Hello, world!')
+    'HELLOWORLD'
+    >>> AZ('Hello, world!'.split())
+    ['HELLO', 'WORLD']
+
+    See Also
+    ========
+
+    check_and_join
+
+    """
+    if not s:
+        return uppercase
+    t = isinstance(s, str)
+    if t:
+        s = [s]
+    rv = [check_and_join(i.upper().split(), uppercase, filter=True)
+        for i in s]
+    if t:
+        return rv[0]
+    return rv
+
+bifid5 = AZ().replace('J', '')
+bifid6 = AZ() + '0123456789'
+bifid10 = printable
+
+
+def padded_key(key, symbols):
+    """Return a string of the distinct characters of ``symbols`` with
+    those of ``key`` appearing first. A ValueError is raised if
+    a) there are duplicate characters in ``symbols`` or
+    b) there are characters in ``key`` that are  not in ``symbols``.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import padded_key
+    >>> padded_key('PUPPY', 'OPQRSTUVWXY')
+    'PUYOQRSTVWX'
+    >>> padded_key('RSA', 'ARTIST')
+    Traceback (most recent call last):
+    ...
+    ValueError: duplicate characters in symbols: T
+
+    """
+    syms = list(uniq(symbols))
+    if len(syms) != len(symbols):
+        extra = ''.join(sorted({
+            i for i in symbols if symbols.count(i) > 1}))
+        raise ValueError('duplicate characters in symbols: %s' % extra)
+    extra = set(key) - set(syms)
+    if extra:
+        raise ValueError(
+            'characters in key but not symbols: %s' % ''.join(
+            sorted(extra)))
+    key0 = ''.join(list(uniq(key)))
+    # remove from syms characters in key0
+    return key0 + translate(''.join(syms), None, key0)
+
+
+def check_and_join(phrase, symbols=None, filter=None):
+    """
+    Joins characters of ``phrase`` and if ``symbols`` is given, raises
+    an error if any character in ``phrase`` is not in ``symbols``.
+
+    Parameters
+    ==========
+
+    phrase
+        String or list of strings to be returned as a string.
+
+    symbols
+        Iterable of characters allowed in ``phrase``.
+
+        If ``symbols`` is ``None``, no checking is performed.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import check_and_join
+    >>> check_and_join('a phrase')
+    'a phrase'
+    >>> check_and_join('a phrase'.upper().split())
+    'APHRASE'
+    >>> check_and_join('a phrase!'.upper().split(), 'ARE', filter=True)
+    'ARAE'
+    >>> check_and_join('a phrase!'.upper().split(), 'ARE')
+    Traceback (most recent call last):
+    ...
+    ValueError: characters in phrase but not symbols: "!HPS"
+
+    """
+    rv = ''.join(''.join(phrase))
+    if symbols is not None:
+        symbols = check_and_join(symbols)
+        missing = ''.join(sorted(set(rv) - set(symbols)))
+        if missing:
+            if not filter:
+                raise ValueError(
+                    'characters in phrase but not symbols: "%s"' % missing)
+            rv = translate(rv, None, missing)
+    return rv
+
+
+def _prep(msg, key, alp, default=None):
+    if not alp:
+        if not default:
+            alp = AZ()
+            msg = AZ(msg)
+            key = AZ(key)
+        else:
+            alp = default
+    else:
+        alp = ''.join(alp)
+    key = check_and_join(key, alp, filter=True)
+    msg = check_and_join(msg, alp, filter=True)
+    return msg, key, alp
+
+
+def cycle_list(k, n):
+    """
+    Returns the elements of the list ``range(n)`` shifted to the
+    left by ``k`` (so the list starts with ``k`` (mod ``n``)).
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import cycle_list
+    >>> cycle_list(3, 10)
+    [3, 4, 5, 6, 7, 8, 9, 0, 1, 2]
+
+    """
+    k = k % n
+    return list(range(k, n)) + list(range(k))
+
+
+######## shift cipher examples ############
+
+
+def encipher_shift(msg, key, symbols=None):
+    """
+    Performs shift cipher encryption on plaintext msg, and returns the
+    ciphertext.
+
+    Parameters
+    ==========
+
+    key : int
+        The secret key.
+
+    msg : str
+        Plaintext of upper-case letters.
+
+    Returns
+    =======
+
+    str
+        Ciphertext of upper-case letters.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encipher_shift, decipher_shift
+    >>> msg = "GONAVYBEATARMY"
+    >>> ct = encipher_shift(msg, 1); ct
+    'HPOBWZCFBUBSNZ'
+
+    To decipher the shifted text, change the sign of the key:
+
+    >>> encipher_shift(ct, -1)
+    'GONAVYBEATARMY'
+
+    There is also a convenience function that does this with the
+    original key:
+
+    >>> decipher_shift(ct, 1)
+    'GONAVYBEATARMY'
+
+    Notes
+    =====
+
+    ALGORITHM:
+
+        STEPS:
+            0. Number the letters of the alphabet from 0, ..., N
+            1. Compute from the string ``msg`` a list ``L1`` of
+               corresponding integers.
+            2. Compute from the list ``L1`` a new list ``L2``, given by
+               adding ``(k mod 26)`` to each element in ``L1``.
+            3. Compute from the list ``L2`` a string ``ct`` of
+               corresponding letters.
+
+    The shift cipher is also called the Caesar cipher, after
+    Julius Caesar, who, according to Suetonius, used it with a
+    shift of three to protect messages of military significance.
+    Caesar's nephew Augustus reportedly used a similar cipher, but
+    with a right shift of 1.
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Caesar_cipher
+    .. [2] https://mathworld.wolfram.com/CaesarsMethod.html
+
+    See Also
+    ========
+
+    decipher_shift
+
+    """
+    msg, _, A = _prep(msg, '', symbols)
+    shift = len(A) - key % len(A)
+    key = A[shift:] + A[:shift]
+    return translate(msg, key, A)
+
+
+def decipher_shift(msg, key, symbols=None):
+    """
+    Return the text by shifting the characters of ``msg`` to the
+    left by the amount given by ``key``.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encipher_shift, decipher_shift
+    >>> msg = "GONAVYBEATARMY"
+    >>> ct = encipher_shift(msg, 1); ct
+    'HPOBWZCFBUBSNZ'
+
+    To decipher the shifted text, change the sign of the key:
+
+    >>> encipher_shift(ct, -1)
+    'GONAVYBEATARMY'
+
+    Or use this function with the original key:
+
+    >>> decipher_shift(ct, 1)
+    'GONAVYBEATARMY'
+
+    """
+    return encipher_shift(msg, -key, symbols)
+
+def encipher_rot13(msg, symbols=None):
+    """
+    Performs the ROT13 encryption on a given plaintext ``msg``.
+
+    Explanation
+    ===========
+
+    ROT13 is a substitution cipher which substitutes each letter
+    in the plaintext message for the letter furthest away from it
+    in the English alphabet.
+
+    Equivalently, it is just a Caeser (shift) cipher with a shift
+    key of 13 (midway point of the alphabet).
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/ROT13
+
+    See Also
+    ========
+
+    decipher_rot13
+    encipher_shift
+
+    """
+    return encipher_shift(msg, 13, symbols)
+
+def decipher_rot13(msg, symbols=None):
+    """
+    Performs the ROT13 decryption on a given plaintext ``msg``.
+
+    Explanation
+    ============
+
+    ``decipher_rot13`` is equivalent to ``encipher_rot13`` as both
+    ``decipher_shift`` with a key of 13 and ``encipher_shift`` key with a
+    key of 13 will return the same results. Nonetheless,
+    ``decipher_rot13`` has nonetheless been explicitly defined here for
+    consistency.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encipher_rot13, decipher_rot13
+    >>> msg = 'GONAVYBEATARMY'
+    >>> ciphertext = encipher_rot13(msg);ciphertext
+    'TBANILORNGNEZL'
+    >>> decipher_rot13(ciphertext)
+    'GONAVYBEATARMY'
+    >>> encipher_rot13(msg) == decipher_rot13(msg)
+    True
+    >>> msg == decipher_rot13(ciphertext)
+    True
+
+    """
+    return decipher_shift(msg, 13, symbols)
+
+######## affine cipher examples ############
+
+
+def encipher_affine(msg, key, symbols=None, _inverse=False):
+    r"""
+    Performs the affine cipher encryption on plaintext ``msg``, and
+    returns the ciphertext.
+
+    Explanation
+    ===========
+
+    Encryption is based on the map `x \rightarrow ax+b` (mod `N`)
+    where ``N`` is the number of characters in the alphabet.
+    Decryption is based on the map `x \rightarrow cx+d` (mod `N`),
+    where `c = a^{-1}` (mod `N`) and `d = -a^{-1}b` (mod `N`).
+    In particular, for the map to be invertible, we need
+    `\mathrm{gcd}(a, N) = 1` and an error will be raised if this is
+    not true.
+
+    Parameters
+    ==========
+
+    msg : str
+        Characters that appear in ``symbols``.
+
+    a, b : int, int
+        A pair integers, with ``gcd(a, N) = 1`` (the secret key).
+
+    symbols
+        String of characters (default = uppercase letters).
+
+        When no symbols are given, ``msg`` is converted to upper case
+        letters and all other characters are ignored.
+
+    Returns
+    =======
+
+    ct
+        String of characters (the ciphertext message)
+
+    Notes
+    =====
+
+    ALGORITHM:
+
+        STEPS:
+            0. Number the letters of the alphabet from 0, ..., N
+            1. Compute from the string ``msg`` a list ``L1`` of
+               corresponding integers.
+            2. Compute from the list ``L1`` a new list ``L2``, given by
+               replacing ``x`` by ``a*x + b (mod N)``, for each element
+               ``x`` in ``L1``.
+            3. Compute from the list ``L2`` a string ``ct`` of
+               corresponding letters.
+
+    This is a straightforward generalization of the shift cipher with
+    the added complexity of requiring 2 characters to be deciphered in
+    order to recover the key.
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Affine_cipher
+
+    See Also
+    ========
+
+    decipher_affine
+
+    """
+    msg, _, A = _prep(msg, '', symbols)
+    N = len(A)
+    a, b = key
+    assert gcd(a, N) == 1
+    if _inverse:
+        c = mod_inverse(a, N)
+        d = -b*c
+        a, b = c, d
+    B = ''.join([A[(a*i + b) % N] for i in range(N)])
+    return translate(msg, A, B)
+
+
+def decipher_affine(msg, key, symbols=None):
+    r"""
+    Return the deciphered text that was made from the mapping,
+    `x \rightarrow ax+b` (mod `N`), where ``N`` is the
+    number of characters in the alphabet. Deciphering is done by
+    reciphering with a new key: `x \rightarrow cx+d` (mod `N`),
+    where `c = a^{-1}` (mod `N`) and `d = -a^{-1}b` (mod `N`).
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encipher_affine, decipher_affine
+    >>> msg = "GO NAVY BEAT ARMY"
+    >>> key = (3, 1)
+    >>> encipher_affine(msg, key)
+    'TROBMVENBGBALV'
+    >>> decipher_affine(_, key)
+    'GONAVYBEATARMY'
+
+    See Also
+    ========
+
+    encipher_affine
+
+    """
+    return encipher_affine(msg, key, symbols, _inverse=True)
+
+
+def encipher_atbash(msg, symbols=None):
+    r"""
+    Enciphers a given ``msg`` into its Atbash ciphertext and returns it.
+
+    Explanation
+    ===========
+
+    Atbash is a substitution cipher originally used to encrypt the Hebrew
+    alphabet. Atbash works on the principle of mapping each alphabet to its
+    reverse / counterpart (i.e. a would map to z, b to y etc.)
+
+    Atbash is functionally equivalent to the affine cipher with ``a = 25``
+    and ``b = 25``
+
+    See Also
+    ========
+
+    decipher_atbash
+
+    """
+    return encipher_affine(msg, (25, 25), symbols)
+
+
+def decipher_atbash(msg, symbols=None):
+    r"""
+    Deciphers a given ``msg`` using Atbash cipher and returns it.
+
+    Explanation
+    ===========
+
+    ``decipher_atbash`` is functionally equivalent to ``encipher_atbash``.
+    However, it has still been added as a separate function to maintain
+    consistency.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encipher_atbash, decipher_atbash
+    >>> msg = 'GONAVYBEATARMY'
+    >>> encipher_atbash(msg)
+    'TLMZEBYVZGZINB'
+    >>> decipher_atbash(msg)
+    'TLMZEBYVZGZINB'
+    >>> encipher_atbash(msg) == decipher_atbash(msg)
+    True
+    >>> msg == encipher_atbash(encipher_atbash(msg))
+    True
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Atbash
+
+    See Also
+    ========
+
+    encipher_atbash
+
+    """
+    return decipher_affine(msg, (25, 25), symbols)
+
+#################### substitution cipher ###########################
+
+
+def encipher_substitution(msg, old, new=None):
+    r"""
+    Returns the ciphertext obtained by replacing each character that
+    appears in ``old`` with the corresponding character in ``new``.
+    If ``old`` is a mapping, then new is ignored and the replacements
+    defined by ``old`` are used.
+
+    Explanation
+    ===========
+
+    This is a more general than the affine cipher in that the key can
+    only be recovered by determining the mapping for each symbol.
+    Though in practice, once a few symbols are recognized the mappings
+    for other characters can be quickly guessed.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encipher_substitution, AZ
+    >>> old = 'OEYAG'
+    >>> new = '034^6'
+    >>> msg = AZ("go navy! beat army!")
+    >>> ct = encipher_substitution(msg, old, new); ct
+    '60N^V4B3^T^RM4'
+
+    To decrypt a substitution, reverse the last two arguments:
+
+    >>> encipher_substitution(ct, new, old)
+    'GONAVYBEATARMY'
+
+    In the special case where ``old`` and ``new`` are a permutation of
+    order 2 (representing a transposition of characters) their order
+    is immaterial:
+
+    >>> old = 'NAVY'
+    >>> new = 'ANYV'
+    >>> encipher = lambda x: encipher_substitution(x, old, new)
+    >>> encipher('NAVY')
+    'ANYV'
+    >>> encipher(_)
+    'NAVY'
+
+    The substitution cipher, in general, is a method
+    whereby "units" (not necessarily single characters) of plaintext
+    are replaced with ciphertext according to a regular system.
+
+    >>> ords = dict(zip('abc', ['\\%i' % ord(i) for i in 'abc']))
+    >>> print(encipher_substitution('abc', ords))
+    \97\98\99
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Substitution_cipher
+
+    """
+    return translate(msg, old, new)
+
+
+######################################################################
+#################### Vigenere cipher examples ########################
+######################################################################
+
+def encipher_vigenere(msg, key, symbols=None):
+    """
+    Performs the Vigenere cipher encryption on plaintext ``msg``, and
+    returns the ciphertext.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encipher_vigenere, AZ
+    >>> key = "encrypt"
+    >>> msg = "meet me on monday"
+    >>> encipher_vigenere(msg, key)
+    'QRGKKTHRZQEBPR'
+
+    Section 1 of the Kryptos sculpture at the CIA headquarters
+    uses this cipher and also changes the order of the
+    alphabet [2]_. Here is the first line of that section of
+    the sculpture:
+
+    >>> from sympy.crypto.crypto import decipher_vigenere, padded_key
+    >>> alp = padded_key('KRYPTOS', AZ())
+    >>> key = 'PALIMPSEST'
+    >>> msg = 'EMUFPHZLRFAXYUSDJKZLDKRNSHGNFIVJ'
+    >>> decipher_vigenere(msg, key, alp)
+    'BETWEENSUBTLESHADINGANDTHEABSENC'
+
+    Explanation
+    ===========
+
+    The Vigenere cipher is named after Blaise de Vigenere, a sixteenth
+    century diplomat and cryptographer, by a historical accident.
+    Vigenere actually invented a different and more complicated cipher.
+    The so-called *Vigenere cipher* was actually invented
+    by Giovan Batista Belaso in 1553.
+
+    This cipher was used in the 1800's, for example, during the American
+    Civil War. The Confederacy used a brass cipher disk to implement the
+    Vigenere cipher (now on display in the NSA Museum in Fort
+    Meade) [1]_.
+
+    The Vigenere cipher is a generalization of the shift cipher.
+    Whereas the shift cipher shifts each letter by the same amount
+    (that amount being the key of the shift cipher) the Vigenere
+    cipher shifts a letter by an amount determined by the key (which is
+    a word or phrase known only to the sender and receiver).
+
+    For example, if the key was a single letter, such as "C", then the
+    so-called Vigenere cipher is actually a shift cipher with a
+    shift of `2` (since "C" is the 2nd letter of the alphabet, if
+    you start counting at `0`). If the key was a word with two
+    letters, such as "CA", then the so-called Vigenere cipher will
+    shift letters in even positions by `2` and letters in odd positions
+    are left alone (shifted by `0`, since "A" is the 0th letter, if
+    you start counting at `0`).
+
+
+    ALGORITHM:
+
+        INPUT:
+
+            ``msg``: string of characters that appear in ``symbols``
+            (the plaintext)
+
+            ``key``: a string of characters that appear in ``symbols``
+            (the secret key)
+
+            ``symbols``: a string of letters defining the alphabet
+
+
+        OUTPUT:
+
+            ``ct``: string of characters (the ciphertext message)
+
+        STEPS:
+            0. Number the letters of the alphabet from 0, ..., N
+            1. Compute from the string ``key`` a list ``L1`` of
+               corresponding integers. Let ``n1 = len(L1)``.
+            2. Compute from the string ``msg`` a list ``L2`` of
+               corresponding integers. Let ``n2 = len(L2)``.
+            3. Break ``L2`` up sequentially into sublists of size
+               ``n1``; the last sublist may be smaller than ``n1``
+            4. For each of these sublists ``L`` of ``L2``, compute a
+               new list ``C`` given by ``C[i] = L[i] + L1[i] (mod N)``
+               to the ``i``-th element in the sublist, for each ``i``.
+            5. Assemble these lists ``C`` by concatenation into a new
+               list of length ``n2``.
+            6. Compute from the new list a string ``ct`` of
+               corresponding letters.
+
+    Once it is known that the key is, say, `n` characters long,
+    frequency analysis can be applied to every `n`-th letter of
+    the ciphertext to determine the plaintext. This method is
+    called *Kasiski examination* (although it was first discovered
+    by Babbage). If they key is as long as the message and is
+    comprised of randomly selected characters -- a one-time pad -- the
+    message is theoretically unbreakable.
+
+    The cipher Vigenere actually discovered is an "auto-key" cipher
+    described as follows.
+
+    ALGORITHM:
+
+        INPUT:
+
+          ``key``: a string of letters (the secret key)
+
+          ``msg``: string of letters (the plaintext message)
+
+        OUTPUT:
+
+          ``ct``: string of upper-case letters (the ciphertext message)
+
+        STEPS:
+            0. Number the letters of the alphabet from 0, ..., N
+            1. Compute from the string ``msg`` a list ``L2`` of
+               corresponding integers. Let ``n2 = len(L2)``.
+            2. Let ``n1`` be the length of the key. Append to the
+               string ``key`` the first ``n2 - n1`` characters of
+               the plaintext message. Compute from this string (also of
+               length ``n2``) a list ``L1`` of integers corresponding
+               to the letter numbers in the first step.
+            3. Compute a new list ``C`` given by
+               ``C[i] = L1[i] + L2[i] (mod N)``.
+            4. Compute from the new list a string ``ct`` of letters
+               corresponding to the new integers.
+
+    To decipher the auto-key ciphertext, the key is used to decipher
+    the first ``n1`` characters and then those characters become the
+    key to  decipher the next ``n1`` characters, etc...:
+
+    >>> m = AZ('go navy, beat army! yes you can'); m
+    'GONAVYBEATARMYYESYOUCAN'
+    >>> key = AZ('gold bug'); n1 = len(key); n2 = len(m)
+    >>> auto_key = key + m[:n2 - n1]; auto_key
+    'GOLDBUGGONAVYBEATARMYYE'
+    >>> ct = encipher_vigenere(m, auto_key); ct
+    'MCYDWSHKOGAMKZCELYFGAYR'
+    >>> n1 = len(key)
+    >>> pt = []
+    >>> while ct:
+    ...     part, ct = ct[:n1], ct[n1:]
+    ...     pt.append(decipher_vigenere(part, key))
+    ...     key = pt[-1]
+    ...
+    >>> ''.join(pt) == m
+    True
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Vigenere_cipher
+    .. [2] https://web.archive.org/web/20071116100808/https://filebox.vt.edu/users/batman/kryptos.html
+       (short URL: https://goo.gl/ijr22d)
+
+    """
+    msg, key, A = _prep(msg, key, symbols)
+    map = {c: i for i, c in enumerate(A)}
+    key = [map[c] for c in key]
+    N = len(map)
+    k = len(key)
+    rv = []
+    for i, m in enumerate(msg):
+        rv.append(A[(map[m] + key[i % k]) % N])
+    rv = ''.join(rv)
+    return rv
+
+
+def decipher_vigenere(msg, key, symbols=None):
+    """
+    Decode using the Vigenere cipher.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import decipher_vigenere
+    >>> key = "encrypt"
+    >>> ct = "QRGK kt HRZQE BPR"
+    >>> decipher_vigenere(ct, key)
+    'MEETMEONMONDAY'
+
+    """
+    msg, key, A = _prep(msg, key, symbols)
+    map = {c: i for i, c in enumerate(A)}
+    N = len(A)   # normally, 26
+    K = [map[c] for c in key]
+    n = len(K)
+    C = [map[c] for c in msg]
+    rv = ''.join([A[(-K[i % n] + c) % N] for i, c in enumerate(C)])
+    return rv
+
+
+#################### Hill cipher  ########################
+
+
+def encipher_hill(msg, key, symbols=None, pad="Q"):
+    r"""
+    Return the Hill cipher encryption of ``msg``.
+
+    Explanation
+    ===========
+
+    The Hill cipher [1]_, invented by Lester S. Hill in the 1920's [2]_,
+    was the first polygraphic cipher in which it was practical
+    (though barely) to operate on more than three symbols at once.
+    The following discussion assumes an elementary knowledge of
+    matrices.
+
+    First, each letter is first encoded as a number starting with 0.
+    Suppose your message `msg` consists of `n` capital letters, with no
+    spaces. This may be regarded an `n`-tuple M of elements of
+    `Z_{26}` (if the letters are those of the English alphabet). A key
+    in the Hill cipher is a `k x k` matrix `K`, all of whose entries
+    are in `Z_{26}`, such that the matrix `K` is invertible (i.e., the
+    linear transformation `K: Z_{N}^k \rightarrow Z_{N}^k`
+    is one-to-one).
+
+
+    Parameters
+    ==========
+
+    msg
+        Plaintext message of `n` upper-case letters.
+
+    key
+        A `k \times k` invertible matrix `K`, all of whose entries are
+        in `Z_{26}` (or whatever number of symbols are being used).
+
+    pad
+        Character (default "Q") to use to make length of text be a
+        multiple of ``k``.
+
+    Returns
+    =======
+
+    ct
+        Ciphertext of upper-case letters.
+
+    Notes
+    =====
+
+    ALGORITHM:
+
+        STEPS:
+            0. Number the letters of the alphabet from 0, ..., N
+            1. Compute from the string ``msg`` a list ``L`` of
+               corresponding integers. Let ``n = len(L)``.
+            2. Break the list ``L`` up into ``t = ceiling(n/k)``
+               sublists ``L_1``, ..., ``L_t`` of size ``k`` (with
+               the last list "padded" to ensure its size is
+               ``k``).
+            3. Compute new list ``C_1``, ..., ``C_t`` given by
+               ``C[i] = K*L_i`` (arithmetic is done mod N), for each
+               ``i``.
+            4. Concatenate these into a list ``C = C_1 + ... + C_t``.
+            5. Compute from ``C`` a string ``ct`` of corresponding
+               letters. This has length ``k*t``.
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Hill_cipher
+    .. [2] Lester S. Hill, Cryptography in an Algebraic Alphabet,
+       The American Mathematical Monthly Vol.36, June-July 1929,
+       pp.306-312.
+
+    See Also
+    ========
+
+    decipher_hill
+
+    """
+    assert key.is_square
+    assert len(pad) == 1
+    msg, pad, A = _prep(msg, pad, symbols)
+    map = {c: i for i, c in enumerate(A)}
+    P = [map[c] for c in msg]
+    N = len(A)
+    k = key.cols
+    n = len(P)
+    m, r = divmod(n, k)
+    if r:
+        P = P + [map[pad]]*(k - r)
+        m += 1
+    rv = ''.join([A[c % N] for j in range(m) for c in
+        list(key*Matrix(k, 1, [P[i]
+        for i in range(k*j, k*(j + 1))]))])
+    return rv
+
+
+def decipher_hill(msg, key, symbols=None):
+    """
+    Deciphering is the same as enciphering but using the inverse of the
+    key matrix.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encipher_hill, decipher_hill
+    >>> from sympy import Matrix
+
+    >>> key = Matrix([[1, 2], [3, 5]])
+    >>> encipher_hill("meet me on monday", key)
+    'UEQDUEODOCTCWQ'
+    >>> decipher_hill(_, key)
+    'MEETMEONMONDAY'
+
+    When the length of the plaintext (stripped of invalid characters)
+    is not a multiple of the key dimension, extra characters will
+    appear at the end of the enciphered and deciphered text. In order to
+    decipher the text, those characters must be included in the text to
+    be deciphered. In the following, the key has a dimension of 4 but
+    the text is 2 short of being a multiple of 4 so two characters will
+    be added.
+
+    >>> key = Matrix([[1, 1, 1, 2], [0, 1, 1, 0],
+    ...               [2, 2, 3, 4], [1, 1, 0, 1]])
+    >>> msg = "ST"
+    >>> encipher_hill(msg, key)
+    'HJEB'
+    >>> decipher_hill(_, key)
+    'STQQ'
+    >>> encipher_hill(msg, key, pad="Z")
+    'ISPK'
+    >>> decipher_hill(_, key)
+    'STZZ'
+
+    If the last two characters of the ciphertext were ignored in
+    either case, the wrong plaintext would be recovered:
+
+    >>> decipher_hill("HD", key)
+    'ORMV'
+    >>> decipher_hill("IS", key)
+    'UIKY'
+
+    See Also
+    ========
+
+    encipher_hill
+
+    """
+    assert key.is_square
+    msg, _, A = _prep(msg, '', symbols)
+    map = {c: i for i, c in enumerate(A)}
+    C = [map[c] for c in msg]
+    N = len(A)
+    k = key.cols
+    n = len(C)
+    m, r = divmod(n, k)
+    if r:
+        C = C + [0]*(k - r)
+        m += 1
+    key_inv = key.inv_mod(N)
+    rv = ''.join([A[p % N] for j in range(m) for p in
+        list(key_inv*Matrix(
+        k, 1, [C[i] for i in range(k*j, k*(j + 1))]))])
+    return rv
+
+
+#################### Bifid cipher  ########################
+
+
+def encipher_bifid(msg, key, symbols=None):
+    r"""
+    Performs the Bifid cipher encryption on plaintext ``msg``, and
+    returns the ciphertext.
+
+    This is the version of the Bifid cipher that uses an `n \times n`
+    Polybius square.
+
+    Parameters
+    ==========
+
+    msg
+        Plaintext string.
+
+    key
+        Short string for key.
+
+        Duplicate characters are ignored and then it is padded with the
+        characters in ``symbols`` that were not in the short key.
+
+    symbols
+        `n \times n` characters defining the alphabet.
+
+        (default is string.printable)
+
+    Returns
+    =======
+
+    ciphertext
+        Ciphertext using Bifid5 cipher without spaces.
+
+    See Also
+    ========
+
+    decipher_bifid, encipher_bifid5, encipher_bifid6
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Bifid_cipher
+
+    """
+    msg, key, A = _prep(msg, key, symbols, bifid10)
+    long_key = ''.join(uniq(key)) or A
+
+    n = len(A)**.5
+    if n != int(n):
+        raise ValueError(
+            'Length of alphabet (%s) is not a square number.' % len(A))
+    N = int(n)
+    if len(long_key) < N**2:
+      long_key = list(long_key) + [x for x in A if x not in long_key]
+
+    # the fractionalization
+    row_col = {ch: divmod(i, N) for i, ch in enumerate(long_key)}
+    r, c = zip(*[row_col[x] for x in msg])
+    rc = r + c
+    ch = {i: ch for ch, i in row_col.items()}
+    rv = ''.join(ch[i] for i in zip(rc[::2], rc[1::2]))
+    return rv
+
+
+def decipher_bifid(msg, key, symbols=None):
+    r"""
+    Performs the Bifid cipher decryption on ciphertext ``msg``, and
+    returns the plaintext.
+
+    This is the version of the Bifid cipher that uses the `n \times n`
+    Polybius square.
+
+    Parameters
+    ==========
+
+    msg
+        Ciphertext string.
+
+    key
+        Short string for key.
+
+        Duplicate characters are ignored and then it is padded with the
+        characters in symbols that were not in the short key.
+
+    symbols
+        `n \times n` characters defining the alphabet.
+
+        (default=string.printable, a `10 \times 10` matrix)
+
+    Returns
+    =======
+
+    deciphered
+        Deciphered text.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import (
+    ...     encipher_bifid, decipher_bifid, AZ)
+
+    Do an encryption using the bifid5 alphabet:
+
+    >>> alp = AZ().replace('J', '')
+    >>> ct = AZ("meet me on monday!")
+    >>> key = AZ("gold bug")
+    >>> encipher_bifid(ct, key, alp)
+    'IEILHHFSTSFQYE'
+
+    When entering the text or ciphertext, spaces are ignored so it
+    can be formatted as desired. Re-entering the ciphertext from the
+    preceding, putting 4 characters per line and padding with an extra
+    J, does not cause problems for the deciphering:
+
+    >>> decipher_bifid('''
+    ... IEILH
+    ... HFSTS
+    ... FQYEJ''', key, alp)
+    'MEETMEONMONDAY'
+
+    When no alphabet is given, all 100 printable characters will be
+    used:
+
+    >>> key = ''
+    >>> encipher_bifid('hello world!', key)
+    'bmtwmg-bIo*w'
+    >>> decipher_bifid(_, key)
+    'hello world!'
+
+    If the key is changed, a different encryption is obtained:
+
+    >>> key = 'gold bug'
+    >>> encipher_bifid('hello world!', 'gold_bug')
+    'hg2sfuei7t}w'
+
+    And if the key used to decrypt the message is not exact, the
+    original text will not be perfectly obtained:
+
+    >>> decipher_bifid(_, 'gold pug')
+    'heldo~wor6d!'
+
+    """
+    msg, _, A = _prep(msg, '', symbols, bifid10)
+    long_key = ''.join(uniq(key)) or A
+
+    n = len(A)**.5
+    if n != int(n):
+        raise ValueError(
+            'Length of alphabet (%s) is not a square number.' % len(A))
+    N = int(n)
+    if len(long_key) < N**2:
+        long_key = list(long_key) + [x for x in A if x not in long_key]
+
+    # the reverse fractionalization
+    row_col = {
+        ch: divmod(i, N) for i, ch in enumerate(long_key)}
+    rc = [i for c in msg for i in row_col[c]]
+    n = len(msg)
+    rc = zip(*(rc[:n], rc[n:]))
+    ch = {i: ch for ch, i in row_col.items()}
+    rv = ''.join(ch[i] for i in rc)
+    return rv
+
+
+def bifid_square(key):
+    """Return characters of ``key`` arranged in a square.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import (
+    ...    bifid_square, AZ, padded_key, bifid5)
+    >>> bifid_square(AZ().replace('J', ''))
+    Matrix([
+    [A, B, C, D, E],
+    [F, G, H, I, K],
+    [L, M, N, O, P],
+    [Q, R, S, T, U],
+    [V, W, X, Y, Z]])
+
+    >>> bifid_square(padded_key(AZ('gold bug!'), bifid5))
+    Matrix([
+    [G, O, L, D, B],
+    [U, A, C, E, F],
+    [H, I, K, M, N],
+    [P, Q, R, S, T],
+    [V, W, X, Y, Z]])
+
+    See Also
+    ========
+
+    padded_key
+
+    """
+    A = ''.join(uniq(''.join(key)))
+    n = len(A)**.5
+    if n != int(n):
+        raise ValueError(
+            'Length of alphabet (%s) is not a square number.' % len(A))
+    n = int(n)
+    f = lambda i, j: Symbol(A[n*i + j])
+    rv = Matrix(n, n, f)
+    return rv
+
+
+def encipher_bifid5(msg, key):
+    r"""
+    Performs the Bifid cipher encryption on plaintext ``msg``, and
+    returns the ciphertext.
+
+    Explanation
+    ===========
+
+    This is the version of the Bifid cipher that uses the `5 \times 5`
+    Polybius square. The letter "J" is ignored so it must be replaced
+    with something else (traditionally an "I") before encryption.
+
+    ALGORITHM: (5x5 case)
+
+        STEPS:
+            0. Create the `5 \times 5` Polybius square ``S`` associated
+               to ``key`` as follows:
+
+                a) moving from left-to-right, top-to-bottom,
+                   place the letters of the key into a `5 \times 5`
+                   matrix,
+                b) if the key has less than 25 letters, add the
+                   letters of the alphabet not in the key until the
+                   `5 \times 5` square is filled.
+
+            1. Create a list ``P`` of pairs of numbers which are the
+               coordinates in the Polybius square of the letters in
+               ``msg``.
+            2. Let ``L1`` be the list of all first coordinates of ``P``
+               (length of ``L1 = n``), let ``L2`` be the list of all
+               second coordinates of ``P`` (so the length of ``L2``
+               is also ``n``).
+            3. Let ``L`` be the concatenation of ``L1`` and ``L2``
+               (length ``L = 2*n``), except that consecutive numbers
+               are paired ``(L[2*i], L[2*i + 1])``. You can regard
+               ``L`` as a list of pairs of length ``n``.
+            4. Let ``C`` be the list of all letters which are of the
+               form ``S[i, j]``, for all ``(i, j)`` in ``L``. As a
+               string, this is the ciphertext of ``msg``.
+
+    Parameters
+    ==========
+
+    msg : str
+        Plaintext string.
+
+        Converted to upper case and filtered of anything but all letters
+        except J.
+
+    key
+        Short string for key; non-alphabetic letters, J and duplicated
+        characters are ignored and then, if the length is less than 25
+        characters, it is padded with other letters of the alphabet
+        (in alphabetical order).
+
+    Returns
+    =======
+
+    ct
+        Ciphertext (all caps, no spaces).
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import (
+    ...     encipher_bifid5, decipher_bifid5)
+
+    "J" will be omitted unless it is replaced with something else:
+
+    >>> round_trip = lambda m, k: \
+    ...     decipher_bifid5(encipher_bifid5(m, k), k)
+    >>> key = 'a'
+    >>> msg = "JOSIE"
+    >>> round_trip(msg, key)
+    'OSIE'
+    >>> round_trip(msg.replace("J", "I"), key)
+    'IOSIE'
+    >>> j = "QIQ"
+    >>> round_trip(msg.replace("J", j), key).replace(j, "J")
+    'JOSIE'
+
+
+    Notes
+    =====
+
+    The Bifid cipher was invented around 1901 by Felix Delastelle.
+    It is a *fractional substitution* cipher, where letters are
+    replaced by pairs of symbols from a smaller alphabet. The
+    cipher uses a `5 \times 5` square filled with some ordering of the
+    alphabet, except that "J" is replaced with "I" (this is a so-called
+    Polybius square; there is a `6 \times 6` analog if you add back in
+    "J" and also append onto the usual 26 letter alphabet, the digits
+    0, 1, ..., 9).
+    According to Helen Gaines' book *Cryptanalysis*, this type of cipher
+    was used in the field by the German Army during World War I.
+
+    See Also
+    ========
+
+    decipher_bifid5, encipher_bifid
+
+    """
+    msg, key, _ = _prep(msg.upper(), key.upper(), None, bifid5)
+    key = padded_key(key, bifid5)
+    return encipher_bifid(msg, '', key)
+
+
+def decipher_bifid5(msg, key):
+    r"""
+    Return the Bifid cipher decryption of ``msg``.
+
+    Explanation
+    ===========
+
+    This is the version of the Bifid cipher that uses the `5 \times 5`
+    Polybius square; the letter "J" is ignored unless a ``key`` of
+    length 25 is used.
+
+    Parameters
+    ==========
+
+    msg
+        Ciphertext string.
+
+    key
+        Short string for key; duplicated characters are ignored and if
+        the length is less then 25 characters, it will be padded with
+        other letters from the alphabet omitting "J".
+        Non-alphabetic characters are ignored.
+
+    Returns
+    =======
+
+    plaintext
+        Plaintext from Bifid5 cipher (all caps, no spaces).
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encipher_bifid5, decipher_bifid5
+    >>> key = "gold bug"
+    >>> encipher_bifid5('meet me on friday', key)
+    'IEILEHFSTSFXEE'
+    >>> encipher_bifid5('meet me on monday', key)
+    'IEILHHFSTSFQYE'
+    >>> decipher_bifid5(_, key)
+    'MEETMEONMONDAY'
+
+    """
+    msg, key, _ = _prep(msg.upper(), key.upper(), None, bifid5)
+    key = padded_key(key, bifid5)
+    return decipher_bifid(msg, '', key)
+
+
+def bifid5_square(key=None):
+    r"""
+    5x5 Polybius square.
+
+    Produce the Polybius square for the `5 \times 5` Bifid cipher.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import bifid5_square
+    >>> bifid5_square("gold bug")
+    Matrix([
+    [G, O, L, D, B],
+    [U, A, C, E, F],
+    [H, I, K, M, N],
+    [P, Q, R, S, T],
+    [V, W, X, Y, Z]])
+
+    """
+    if not key:
+        key = bifid5
+    else:
+        _, key, _ = _prep('', key.upper(), None, bifid5)
+        key = padded_key(key, bifid5)
+    return bifid_square(key)
+
+
+def encipher_bifid6(msg, key):
+    r"""
+    Performs the Bifid cipher encryption on plaintext ``msg``, and
+    returns the ciphertext.
+
+    This is the version of the Bifid cipher that uses the `6 \times 6`
+    Polybius square.
+
+    Parameters
+    ==========
+
+    msg
+        Plaintext string (digits okay).
+
+    key
+        Short string for key (digits okay).
+
+        If ``key`` is less than 36 characters long, the square will be
+        filled with letters A through Z and digits 0 through 9.
+
+    Returns
+    =======
+
+    ciphertext
+        Ciphertext from Bifid cipher (all caps, no spaces).
+
+    See Also
+    ========
+
+    decipher_bifid6, encipher_bifid
+
+    """
+    msg, key, _ = _prep(msg.upper(), key.upper(), None, bifid6)
+    key = padded_key(key, bifid6)
+    return encipher_bifid(msg, '', key)
+
+
+def decipher_bifid6(msg, key):
+    r"""
+    Performs the Bifid cipher decryption on ciphertext ``msg``, and
+    returns the plaintext.
+
+    This is the version of the Bifid cipher that uses the `6 \times 6`
+    Polybius square.
+
+    Parameters
+    ==========
+
+    msg
+        Ciphertext string (digits okay); converted to upper case
+
+    key
+        Short string for key (digits okay).
+
+        If ``key`` is less than 36 characters long, the square will be
+        filled with letters A through Z and digits 0 through 9.
+        All letters are converted to uppercase.
+
+    Returns
+    =======
+
+    plaintext
+        Plaintext from Bifid cipher (all caps, no spaces).
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encipher_bifid6, decipher_bifid6
+    >>> key = "gold bug"
+    >>> encipher_bifid6('meet me on monday at 8am', key)
+    'KFKLJJHF5MMMKTFRGPL'
+    >>> decipher_bifid6(_, key)
+    'MEETMEONMONDAYAT8AM'
+
+    """
+    msg, key, _ = _prep(msg.upper(), key.upper(), None, bifid6)
+    key = padded_key(key, bifid6)
+    return decipher_bifid(msg, '', key)
+
+
+def bifid6_square(key=None):
+    r"""
+    6x6 Polybius square.
+
+    Produces the Polybius square for the `6 \times 6` Bifid cipher.
+    Assumes alphabet of symbols is "A", ..., "Z", "0", ..., "9".
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import bifid6_square
+    >>> key = "gold bug"
+    >>> bifid6_square(key)
+    Matrix([
+    [G, O, L, D, B, U],
+    [A, C, E, F, H, I],
+    [J, K, M, N, P, Q],
+    [R, S, T, V, W, X],
+    [Y, Z, 0, 1, 2, 3],
+    [4, 5, 6, 7, 8, 9]])
+
+    """
+    if not key:
+        key = bifid6
+    else:
+        _, key, _ = _prep('', key.upper(), None, bifid6)
+        key = padded_key(key, bifid6)
+    return bifid_square(key)
+
+
+#################### RSA  #############################
+
+def _decipher_rsa_crt(i, d, factors):
+    """Decipher RSA using chinese remainder theorem from the information
+    of the relatively-prime factors of the modulus.
+
+    Parameters
+    ==========
+
+    i : integer
+        Ciphertext
+
+    d : integer
+        The exponent component.
+
+    factors : list of relatively-prime integers
+        The integers given must be coprime and the product must equal
+        the modulus component of the original RSA key.
+
+    Examples
+    ========
+
+    How to decrypt RSA with CRT:
+
+    >>> from sympy.crypto.crypto import rsa_public_key, rsa_private_key
+    >>> primes = [61, 53]
+    >>> e = 17
+    >>> args = primes + [e]
+    >>> puk = rsa_public_key(*args)
+    >>> prk = rsa_private_key(*args)
+
+    >>> from sympy.crypto.crypto import encipher_rsa, _decipher_rsa_crt
+    >>> msg = 65
+    >>> crt_primes = primes
+    >>> encrypted = encipher_rsa(msg, puk)
+    >>> decrypted = _decipher_rsa_crt(encrypted, prk[1], primes)
+    >>> decrypted
+    65
+    """
+    moduluses = [pow(i, d, p) for p in factors]
+
+    result = crt(factors, moduluses)
+    if not result:
+        raise ValueError("CRT failed")
+    return result[0]
+
+
+def _rsa_key(*args, public=True, private=True, totient='Euler', index=None, multipower=None):
+    r"""A private subroutine to generate RSA key
+
+    Parameters
+    ==========
+
+    public, private : bool, optional
+        Flag to generate either a public key, a private key.
+
+    totient : 'Euler' or 'Carmichael'
+        Different notation used for totient.
+
+    multipower : bool, optional
+        Flag to bypass warning for multipower RSA.
+    """
+
+    if len(args) < 2:
+        return False
+
+    if totient not in ('Euler', 'Carmichael'):
+        raise ValueError(
+            "The argument totient={} should either be " \
+            "'Euler', 'Carmichalel'." \
+            .format(totient))
+
+    if totient == 'Euler':
+        _totient = _euler
+    else:
+        _totient = _carmichael
+
+    if index is not None:
+        index = as_int(index)
+        if totient != 'Carmichael':
+            raise ValueError(
+                "Setting the 'index' keyword argument requires totient"
+                "notation to be specified as 'Carmichael'.")
+
+    primes, e = args[:-1], args[-1]
+
+    if not all(isprime(p) for p in primes):
+        new_primes = []
+        for i in primes:
+            new_primes.extend(factorint(i, multiple=True))
+        primes = new_primes
+
+    n = reduce(lambda i, j: i*j, primes)
+
+    tally = multiset(primes)
+    if all(v == 1 for v in tally.values()):
+        multiple = list(tally.keys())
+        phi = _totient._from_distinct_primes(*multiple)
+
+    else:
+        if not multipower:
+            NonInvertibleCipherWarning(
+                'Non-distinctive primes found in the factors {}. '
+                'The cipher may not be decryptable for some numbers '
+                'in the complete residue system Z[{}], but the cipher '
+                'can still be valid if you restrict the domain to be '
+                'the reduced residue system Z*[{}]. You can pass '
+                'the flag multipower=True if you want to suppress this '
+                'warning.'
+                .format(primes, n, n)
+                # stacklevel=4 because most users will call a function that
+                # calls this function
+                ).warn(stacklevel=4)
+        phi = _totient._from_factors(tally)
+
+    if igcd(e, phi) == 1:
+        if public and not private:
+            if isinstance(index, int):
+                e = e % phi
+                e += index * phi
+            return n, e
+
+        if private and not public:
+            d = mod_inverse(e, phi)
+            if isinstance(index, int):
+                d += index * phi
+            return n, d
+
+    return False
+
+
+def rsa_public_key(*args, **kwargs):
+    r"""Return the RSA *public key* pair, `(n, e)`
+
+    Parameters
+    ==========
+
+    args : naturals
+        If specified as `p, q, e` where `p` and `q` are distinct primes
+        and `e` is a desired public exponent of the RSA, `n = p q` and
+        `e` will be verified against the totient
+        `\phi(n)` (Euler totient) or `\lambda(n)` (Carmichael totient)
+        to be `\gcd(e, \phi(n)) = 1` or `\gcd(e, \lambda(n)) = 1`.
+
+        If specified as `p_1, p_2, \dots, p_n, e` where
+        `p_1, p_2, \dots, p_n` are specified as primes,
+        and `e` is specified as a desired public exponent of the RSA,
+        it will be able to form a multi-prime RSA, which is a more
+        generalized form of the popular 2-prime RSA.
+
+        It can also be possible to form a single-prime RSA by specifying
+        the argument as `p, e`, which can be considered a trivial case
+        of a multiprime RSA.
+
+        Furthermore, it can be possible to form a multi-power RSA by
+        specifying two or more pairs of the primes to be same.
+        However, unlike the two-distinct prime RSA or multi-prime
+        RSA, not every numbers in the complete residue system
+        (`\mathbb{Z}_n`) will be decryptable since the mapping
+        `\mathbb{Z}_{n} \rightarrow \mathbb{Z}_{n}`
+        will not be bijective.
+        (Only except for the trivial case when
+        `e = 1`
+        or more generally,
+
+        .. math::
+            e \in \left \{ 1 + k \lambda(n)
+            \mid k \in \mathbb{Z} \land k \geq 0 \right \}
+
+        when RSA reduces to the identity.)
+        However, the RSA can still be decryptable for the numbers in the
+        reduced residue system (`\mathbb{Z}_n^{\times}`), since the
+        mapping
+        `\mathbb{Z}_{n}^{\times} \rightarrow \mathbb{Z}_{n}^{\times}`
+        can still be bijective.
+
+        If you pass a non-prime integer to the arguments
+        `p_1, p_2, \dots, p_n`, the particular number will be
+        prime-factored and it will become either a multi-prime RSA or a
+        multi-power RSA in its canonical form, depending on whether the
+        product equals its radical or not.
+        `p_1 p_2 \dots p_n = \text{rad}(p_1 p_2 \dots p_n)`
+
+    totient : bool, optional
+        If ``'Euler'``, it uses Euler's totient `\phi(n)` which is
+        :meth:`sympy.ntheory.factor_.totient` in SymPy.
+
+        If ``'Carmichael'``, it uses Carmichael's totient `\lambda(n)`
+        which is :meth:`sympy.ntheory.factor_.reduced_totient` in SymPy.
+
+        Unlike private key generation, this is a trivial keyword for
+        public key generation because
+        `\gcd(e, \phi(n)) = 1 \iff \gcd(e, \lambda(n)) = 1`.
+
+    index : nonnegative integer, optional
+        Returns an arbitrary solution of a RSA public key at the index
+        specified at `0, 1, 2, \dots`. This parameter needs to be
+        specified along with ``totient='Carmichael'``.
+
+        Similarly to the non-uniquenss of a RSA private key as described
+        in the ``index`` parameter documentation in
+        :meth:`rsa_private_key`, RSA public key is also not unique and
+        there is an infinite number of RSA public exponents which
+        can behave in the same manner.
+
+        From any given RSA public exponent `e`, there are can be an
+        another RSA public exponent `e + k \lambda(n)` where `k` is an
+        integer, `\lambda` is a Carmichael's totient function.
+
+        However, considering only the positive cases, there can be
+        a principal solution of a RSA public exponent `e_0` in
+        `0 < e_0 < \lambda(n)`, and all the other solutions
+        can be canonicalzed in a form of `e_0 + k \lambda(n)`.
+
+        ``index`` specifies the `k` notation to yield any possible value
+        an RSA public key can have.
+
+        An example of computing any arbitrary RSA public key:
+
+        >>> from sympy.crypto.crypto import rsa_public_key
+        >>> rsa_public_key(61, 53, 17, totient='Carmichael', index=0)
+        (3233, 17)
+        >>> rsa_public_key(61, 53, 17, totient='Carmichael', index=1)
+        (3233, 797)
+        >>> rsa_public_key(61, 53, 17, totient='Carmichael', index=2)
+        (3233, 1577)
+
+    multipower : bool, optional
+        Any pair of non-distinct primes found in the RSA specification
+        will restrict the domain of the cryptosystem, as noted in the
+        explanation of the parameter ``args``.
+
+        SymPy RSA key generator may give a warning before dispatching it
+        as a multi-power RSA, however, you can disable the warning if
+        you pass ``True`` to this keyword.
+
+    Returns
+    =======
+
+    (n, e) : int, int
+        `n` is a product of any arbitrary number of primes given as
+        the argument.
+
+        `e` is relatively prime (coprime) to the Euler totient
+        `\phi(n)`.
+
+    False
+        Returned if less than two arguments are given, or `e` is
+        not relatively prime to the modulus.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import rsa_public_key
+
+    A public key of a two-prime RSA:
+
+    >>> p, q, e = 3, 5, 7
+    >>> rsa_public_key(p, q, e)
+    (15, 7)
+    >>> rsa_public_key(p, q, 30)
+    False
+
+    A public key of a multiprime RSA:
+
+    >>> primes = [2, 3, 5, 7, 11, 13]
+    >>> e = 7
+    >>> args = primes + [e]
+    >>> rsa_public_key(*args)
+    (30030, 7)
+
+    Notes
+    =====
+
+    Although the RSA can be generalized over any modulus `n`, using
+    two large primes had became the most popular specification because a
+    product of two large primes is usually the hardest to factor
+    relatively to the digits of `n` can have.
+
+    However, it may need further understanding of the time complexities
+    of each prime-factoring algorithms to verify the claim.
+
+    See Also
+    ========
+
+    rsa_private_key
+    encipher_rsa
+    decipher_rsa
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/RSA_%28cryptosystem%29
+
+    .. [2] https://cacr.uwaterloo.ca/techreports/2006/cacr2006-16.pdf
+
+    .. [3] https://link.springer.com/content/pdf/10.1007/BFb0055738.pdf
+
+    .. [4] https://www.itiis.org/digital-library/manuscript/1381
+    """
+    return _rsa_key(*args, public=True, private=False, **kwargs)
+
+
+def rsa_private_key(*args, **kwargs):
+    r"""Return the RSA *private key* pair, `(n, d)`
+
+    Parameters
+    ==========
+
+    args : naturals
+        The keyword is identical to the ``args`` in
+        :meth:`rsa_public_key`.
+
+    totient : bool, optional
+        If ``'Euler'``, it uses Euler's totient convention `\phi(n)`
+        which is :meth:`sympy.ntheory.factor_.totient` in SymPy.
+
+        If ``'Carmichael'``, it uses Carmichael's totient convention
+        `\lambda(n)` which is
+        :meth:`sympy.ntheory.factor_.reduced_totient` in SymPy.
+
+        There can be some output differences for private key generation
+        as examples below.
+
+        Example using Euler's totient:
+
+        >>> from sympy.crypto.crypto import rsa_private_key
+        >>> rsa_private_key(61, 53, 17, totient='Euler')
+        (3233, 2753)
+
+        Example using Carmichael's totient:
+
+        >>> from sympy.crypto.crypto import rsa_private_key
+        >>> rsa_private_key(61, 53, 17, totient='Carmichael')
+        (3233, 413)
+
+    index : nonnegative integer, optional
+        Returns an arbitrary solution of a RSA private key at the index
+        specified at `0, 1, 2, \dots`. This parameter needs to be
+        specified along with ``totient='Carmichael'``.
+
+        RSA private exponent is a non-unique solution of
+        `e d \mod \lambda(n) = 1` and it is possible in any form of
+        `d + k \lambda(n)`, where `d` is an another
+        already-computed private exponent, and `\lambda` is a
+        Carmichael's totient function, and `k` is any integer.
+
+        However, considering only the positive cases, there can be
+        a principal solution of a RSA private exponent `d_0` in
+        `0 < d_0 < \lambda(n)`, and all the other solutions
+        can be canonicalzed in a form of `d_0 + k \lambda(n)`.
+
+        ``index`` specifies the `k` notation to yield any possible value
+        an RSA private key can have.
+
+        An example of computing any arbitrary RSA private key:
+
+        >>> from sympy.crypto.crypto import rsa_private_key
+        >>> rsa_private_key(61, 53, 17, totient='Carmichael', index=0)
+        (3233, 413)
+        >>> rsa_private_key(61, 53, 17, totient='Carmichael', index=1)
+        (3233, 1193)
+        >>> rsa_private_key(61, 53, 17, totient='Carmichael', index=2)
+        (3233, 1973)
+
+    multipower : bool, optional
+        The keyword is identical to the ``multipower`` in
+        :meth:`rsa_public_key`.
+
+    Returns
+    =======
+
+    (n, d) : int, int
+        `n` is a product of any arbitrary number of primes given as
+        the argument.
+
+        `d` is the inverse of `e` (mod `\phi(n)`) where `e` is the
+        exponent given, and `\phi` is a Euler totient.
+
+    False
+        Returned if less than two arguments are given, or `e` is
+        not relatively prime to the totient of the modulus.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import rsa_private_key
+
+    A private key of a two-prime RSA:
+
+    >>> p, q, e = 3, 5, 7
+    >>> rsa_private_key(p, q, e)
+    (15, 7)
+    >>> rsa_private_key(p, q, 30)
+    False
+
+    A private key of a multiprime RSA:
+
+    >>> primes = [2, 3, 5, 7, 11, 13]
+    >>> e = 7
+    >>> args = primes + [e]
+    >>> rsa_private_key(*args)
+    (30030, 823)
+
+    See Also
+    ========
+
+    rsa_public_key
+    encipher_rsa
+    decipher_rsa
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/RSA_%28cryptosystem%29
+
+    .. [2] https://cacr.uwaterloo.ca/techreports/2006/cacr2006-16.pdf
+
+    .. [3] https://link.springer.com/content/pdf/10.1007/BFb0055738.pdf
+
+    .. [4] https://www.itiis.org/digital-library/manuscript/1381
+    """
+    return _rsa_key(*args, public=False, private=True, **kwargs)
+
+
+def _encipher_decipher_rsa(i, key, factors=None):
+    n, d = key
+    if not factors:
+        return pow(i, d, n)
+
+    def _is_coprime_set(l):
+        is_coprime_set = True
+        for i in range(len(l)):
+            for j in range(i+1, len(l)):
+                if igcd(l[i], l[j]) != 1:
+                    is_coprime_set = False
+                    break
+        return is_coprime_set
+
+    prod = reduce(lambda i, j: i*j, factors)
+    if prod == n and _is_coprime_set(factors):
+        return _decipher_rsa_crt(i, d, factors)
+    return _encipher_decipher_rsa(i, key, factors=None)
+
+
+def encipher_rsa(i, key, factors=None):
+    r"""Encrypt the plaintext with RSA.
+
+    Parameters
+    ==========
+
+    i : integer
+        The plaintext to be encrypted for.
+
+    key : (n, e) where n, e are integers
+        `n` is the modulus of the key and `e` is the exponent of the
+        key. The encryption is computed by `i^e \bmod n`.
+
+        The key can either be a public key or a private key, however,
+        the message encrypted by a public key can only be decrypted by
+        a private key, and vice versa, as RSA is an asymmetric
+        cryptography system.
+
+    factors : list of coprime integers
+        This is identical to the keyword ``factors`` in
+        :meth:`decipher_rsa`.
+
+    Notes
+    =====
+
+    Some specifications may make the RSA not cryptographically
+    meaningful.
+
+    For example, `0`, `1` will remain always same after taking any
+    number of exponentiation, thus, should be avoided.
+
+    Furthermore, if `i^e < n`, `i` may easily be figured out by taking
+    `e` th root.
+
+    And also, specifying the exponent as `1` or in more generalized form
+    as `1 + k \lambda(n)` where `k` is an nonnegative integer,
+    `\lambda` is a carmichael totient, the RSA becomes an identity
+    mapping.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encipher_rsa
+    >>> from sympy.crypto.crypto import rsa_public_key, rsa_private_key
+
+    Public Key Encryption:
+
+    >>> p, q, e = 3, 5, 7
+    >>> puk = rsa_public_key(p, q, e)
+    >>> msg = 12
+    >>> encipher_rsa(msg, puk)
+    3
+
+    Private Key Encryption:
+
+    >>> p, q, e = 3, 5, 7
+    >>> prk = rsa_private_key(p, q, e)
+    >>> msg = 12
+    >>> encipher_rsa(msg, prk)
+    3
+
+    Encryption using chinese remainder theorem:
+
+    >>> encipher_rsa(msg, prk, factors=[p, q])
+    3
+    """
+    return _encipher_decipher_rsa(i, key, factors=factors)
+
+
+def decipher_rsa(i, key, factors=None):
+    r"""Decrypt the ciphertext with RSA.
+
+    Parameters
+    ==========
+
+    i : integer
+        The ciphertext to be decrypted for.
+
+    key : (n, d) where n, d are integers
+        `n` is the modulus of the key and `d` is the exponent of the
+        key. The decryption is computed by `i^d \bmod n`.
+
+        The key can either be a public key or a private key, however,
+        the message encrypted by a public key can only be decrypted by
+        a private key, and vice versa, as RSA is an asymmetric
+        cryptography system.
+
+    factors : list of coprime integers
+        As the modulus `n` created from RSA key generation is composed
+        of arbitrary prime factors
+        `n = {p_1}^{k_1}{p_2}^{k_2}\dots{p_n}^{k_n}` where
+        `p_1, p_2, \dots, p_n` are distinct primes and
+        `k_1, k_2, \dots, k_n` are positive integers, chinese remainder
+        theorem can be used to compute `i^d \bmod n` from the
+        fragmented modulo operations like
+
+        .. math::
+            i^d \bmod {p_1}^{k_1}, i^d \bmod {p_2}^{k_2}, \dots,
+            i^d \bmod {p_n}^{k_n}
+
+        or like
+
+        .. math::
+            i^d \bmod {p_1}^{k_1}{p_2}^{k_2},
+            i^d \bmod {p_3}^{k_3}, \dots ,
+            i^d \bmod {p_n}^{k_n}
+
+        as long as every moduli does not share any common divisor each
+        other.
+
+        The raw primes used in generating the RSA key pair can be a good
+        option.
+
+        Note that the speed advantage of using this is only viable for
+        very large cases (Like 2048-bit RSA keys) since the
+        overhead of using pure Python implementation of
+        :meth:`sympy.ntheory.modular.crt` may overcompensate the
+        theoretical speed advantage.
+
+    Notes
+    =====
+
+    See the ``Notes`` section in the documentation of
+    :meth:`encipher_rsa`
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import decipher_rsa, encipher_rsa
+    >>> from sympy.crypto.crypto import rsa_public_key, rsa_private_key
+
+    Public Key Encryption and Decryption:
+
+    >>> p, q, e = 3, 5, 7
+    >>> prk = rsa_private_key(p, q, e)
+    >>> puk = rsa_public_key(p, q, e)
+    >>> msg = 12
+    >>> new_msg = encipher_rsa(msg, prk)
+    >>> new_msg
+    3
+    >>> decipher_rsa(new_msg, puk)
+    12
+
+    Private Key Encryption and Decryption:
+
+    >>> p, q, e = 3, 5, 7
+    >>> prk = rsa_private_key(p, q, e)
+    >>> puk = rsa_public_key(p, q, e)
+    >>> msg = 12
+    >>> new_msg = encipher_rsa(msg, puk)
+    >>> new_msg
+    3
+    >>> decipher_rsa(new_msg, prk)
+    12
+
+    Decryption using chinese remainder theorem:
+
+    >>> decipher_rsa(new_msg, prk, factors=[p, q])
+    12
+
+    See Also
+    ========
+
+    encipher_rsa
+    """
+    return _encipher_decipher_rsa(i, key, factors=factors)
+
+
+#################### kid krypto (kid RSA) #############################
+
+
+def kid_rsa_public_key(a, b, A, B):
+    r"""
+    Kid RSA is a version of RSA useful to teach grade school children
+    since it does not involve exponentiation.
+
+    Explanation
+    ===========
+
+    Alice wants to talk to Bob. Bob generates keys as follows.
+    Key generation:
+
+    * Select positive integers `a, b, A, B` at random.
+    * Compute `M = a b - 1`, `e = A M + a`, `d = B M + b`,
+      `n = (e d - 1)//M`.
+    * The *public key* is `(n, e)`. Bob sends these to Alice.
+    * The *private key* is `(n, d)`, which Bob keeps secret.
+
+    Encryption: If `p` is the plaintext message then the
+    ciphertext is `c = p e \pmod n`.
+
+    Decryption: If `c` is the ciphertext message then the
+    plaintext is `p = c d \pmod n`.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import kid_rsa_public_key
+    >>> a, b, A, B = 3, 4, 5, 6
+    >>> kid_rsa_public_key(a, b, A, B)
+    (369, 58)
+
+    """
+    M = a*b - 1
+    e = A*M + a
+    d = B*M + b
+    n = (e*d - 1)//M
+    return n, e
+
+
+def kid_rsa_private_key(a, b, A, B):
+    """
+    Compute `M = a b - 1`, `e = A M + a`, `d = B M + b`,
+    `n = (e d - 1) / M`. The *private key* is `d`, which Bob
+    keeps secret.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import kid_rsa_private_key
+    >>> a, b, A, B = 3, 4, 5, 6
+    >>> kid_rsa_private_key(a, b, A, B)
+    (369, 70)
+
+    """
+    M = a*b - 1
+    e = A*M + a
+    d = B*M + b
+    n = (e*d - 1)//M
+    return n, d
+
+
+def encipher_kid_rsa(msg, key):
+    """
+    Here ``msg`` is the plaintext and ``key`` is the public key.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import (
+    ...     encipher_kid_rsa, kid_rsa_public_key)
+    >>> msg = 200
+    >>> a, b, A, B = 3, 4, 5, 6
+    >>> key = kid_rsa_public_key(a, b, A, B)
+    >>> encipher_kid_rsa(msg, key)
+    161
+
+    """
+    n, e = key
+    return (msg*e) % n
+
+
+def decipher_kid_rsa(msg, key):
+    """
+    Here ``msg`` is the plaintext and ``key`` is the private key.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import (
+    ...     kid_rsa_public_key, kid_rsa_private_key,
+    ...     decipher_kid_rsa, encipher_kid_rsa)
+    >>> a, b, A, B = 3, 4, 5, 6
+    >>> d = kid_rsa_private_key(a, b, A, B)
+    >>> msg = 200
+    >>> pub = kid_rsa_public_key(a, b, A, B)
+    >>> pri = kid_rsa_private_key(a, b, A, B)
+    >>> ct = encipher_kid_rsa(msg, pub)
+    >>> decipher_kid_rsa(ct, pri)
+    200
+
+    """
+    n, d = key
+    return (msg*d) % n
+
+
+#################### Morse Code ######################################
+
+morse_char = {
+    ".-": "A", "-...": "B",
+    "-.-.": "C", "-..": "D",
+    ".": "E", "..-.": "F",
+    "--.": "G", "....": "H",
+    "..": "I", ".---": "J",
+    "-.-": "K", ".-..": "L",
+    "--": "M", "-.": "N",
+    "---": "O", ".--.": "P",
+    "--.-": "Q", ".-.": "R",
+    "...": "S", "-": "T",
+    "..-": "U", "...-": "V",
+    ".--": "W", "-..-": "X",
+    "-.--": "Y", "--..": "Z",
+    "-----": "0", ".----": "1",
+    "..---": "2", "...--": "3",
+    "....-": "4", ".....": "5",
+    "-....": "6", "--...": "7",
+    "---..": "8", "----.": "9",
+    ".-.-.-": ".", "--..--": ",",
+    "---...": ":", "-.-.-.": ";",
+    "..--..": "?", "-....-": "-",
+    "..--.-": "_", "-.--.": "(",
+    "-.--.-": ")", ".----.": "'",
+    "-...-": "=", ".-.-.": "+",
+    "-..-.": "/", ".--.-.": "@",
+    "...-..-": "$", "-.-.--": "!"}
+char_morse = {v: k for k, v in morse_char.items()}
+
+
+def encode_morse(msg, sep='|', mapping=None):
+    """
+    Encodes a plaintext into popular Morse Code with letters
+    separated by ``sep`` and words by a double ``sep``.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encode_morse
+    >>> msg = 'ATTACK RIGHT FLANK'
+    >>> encode_morse(msg)
+    '.-|-|-|.-|-.-.|-.-||.-.|..|--.|....|-||..-.|.-..|.-|-.|-.-'
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Morse_code
+
+    """
+
+    mapping = mapping or char_morse
+    assert sep not in mapping
+    word_sep = 2*sep
+    mapping[" "] = word_sep
+    suffix = msg and msg[-1] in whitespace
+
+    # normalize whitespace
+    msg = (' ' if word_sep else '').join(msg.split())
+    # omit unmapped chars
+    chars = set(''.join(msg.split()))
+    ok = set(mapping.keys())
+    msg = translate(msg, None, ''.join(chars - ok))
+
+    morsestring = []
+    words = msg.split()
+    for word in words:
+        morseword = []
+        for letter in word:
+            morseletter = mapping[letter]
+            morseword.append(morseletter)
+
+        word = sep.join(morseword)
+        morsestring.append(word)
+
+    return word_sep.join(morsestring) + (word_sep if suffix else '')
+
+
+def decode_morse(msg, sep='|', mapping=None):
+    """
+    Decodes a Morse Code with letters separated by ``sep``
+    (default is '|') and words by `word_sep` (default is '||)
+    into plaintext.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import decode_morse
+    >>> mc = '--|---|...-|.||.|.-|...|-'
+    >>> decode_morse(mc)
+    'MOVE EAST'
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Morse_code
+
+    """
+
+    mapping = mapping or morse_char
+    word_sep = 2*sep
+    characterstring = []
+    words = msg.strip(word_sep).split(word_sep)
+    for word in words:
+        letters = word.split(sep)
+        chars = [mapping[c] for c in letters]
+        word = ''.join(chars)
+        characterstring.append(word)
+    rv = " ".join(characterstring)
+    return rv
+
+
+#################### LFSRs  ##########################################
+
+
+def lfsr_sequence(key, fill, n):
+    r"""
+    This function creates an LFSR sequence.
+
+    Parameters
+    ==========
+
+    key : list
+        A list of finite field elements, `[c_0, c_1, \ldots, c_k].`
+
+    fill : list
+        The list of the initial terms of the LFSR sequence,
+        `[x_0, x_1, \ldots, x_k].`
+
+    n
+        Number of terms of the sequence that the function returns.
+
+    Returns
+    =======
+
+    L
+        The LFSR sequence defined by
+        `x_{n+1} = c_k x_n + \ldots + c_0 x_{n-k}`, for
+        `n \leq k`.
+
+    Notes
+    =====
+
+    S. Golomb [G]_ gives a list of three statistical properties a
+    sequence of numbers `a = \{a_n\}_{n=1}^\infty`,
+    `a_n \in \{0,1\}`, should display to be considered
+    "random". Define the autocorrelation of `a` to be
+
+    .. math::
+
+        C(k) = C(k,a) = \lim_{N\rightarrow \infty} {1\over N}\sum_{n=1}^N (-1)^{a_n + a_{n+k}}.
+
+    In the case where `a` is periodic with period
+    `P` then this reduces to
+
+    .. math::
+
+        C(k) = {1\over P}\sum_{n=1}^P (-1)^{a_n + a_{n+k}}.
+
+    Assume `a` is periodic with period `P`.
+
+    - balance:
+
+      .. math::
+
+        \left|\sum_{n=1}^P(-1)^{a_n}\right| \leq 1.
+
+    - low autocorrelation:
+
+       .. math::
+
+         C(k) = \left\{ \begin{array}{cc} 1,& k = 0,\\ \epsilon, & k \ne 0. \end{array} \right.
+
+      (For sequences satisfying these first two properties, it is known
+      that `\epsilon = -1/P` must hold.)
+
+    - proportional runs property: In each period, half the runs have
+      length `1`, one-fourth have length `2`, etc.
+      Moreover, there are as many runs of `1`'s as there are of
+      `0`'s.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import lfsr_sequence
+    >>> from sympy.polys.domains import FF
+    >>> F = FF(2)
+    >>> fill = [F(1), F(1), F(0), F(1)]
+    >>> key = [F(1), F(0), F(0), F(1)]
+    >>> lfsr_sequence(key, fill, 10)
+    [1 mod 2, 1 mod 2, 0 mod 2, 1 mod 2, 0 mod 2,
+    1 mod 2, 1 mod 2, 0 mod 2, 0 mod 2, 1 mod 2]
+
+    References
+    ==========
+
+    .. [G] Solomon Golomb, Shift register sequences, Aegean Park Press,
+       Laguna Hills, Ca, 1967
+
+    """
+    if not isinstance(key, list):
+        raise TypeError("key must be a list")
+    if not isinstance(fill, list):
+        raise TypeError("fill must be a list")
+    p = key[0].mod
+    F = FF(p)
+    s = fill
+    k = len(fill)
+    L = []
+    for i in range(n):
+        s0 = s[:]
+        L.append(s[0])
+        s = s[1:k]
+        x = sum([int(key[i]*s0[i]) for i in range(k)])
+        s.append(F(x))
+    return L       # use [x.to_int() for x in L] for int version
+
+
+def lfsr_autocorrelation(L, P, k):
+    """
+    This function computes the LFSR autocorrelation function.
+
+    Parameters
+    ==========
+
+    L
+        A periodic sequence of elements of `GF(2)`.
+        L must have length larger than P.
+
+    P
+        The period of L.
+
+    k : int
+        An integer `k` (`0 < k < P`).
+
+    Returns
+    =======
+
+    autocorrelation
+        The k-th value of the autocorrelation of the LFSR L.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import (
+    ...     lfsr_sequence, lfsr_autocorrelation)
+    >>> from sympy.polys.domains import FF
+    >>> F = FF(2)
+    >>> fill = [F(1), F(1), F(0), F(1)]
+    >>> key = [F(1), F(0), F(0), F(1)]
+    >>> s = lfsr_sequence(key, fill, 20)
+    >>> lfsr_autocorrelation(s, 15, 7)
+    -1/15
+    >>> lfsr_autocorrelation(s, 15, 0)
+    1
+
+    """
+    if not isinstance(L, list):
+        raise TypeError("L (=%s) must be a list" % L)
+    P = int(P)
+    k = int(k)
+    L0 = L[:P]     # slices makes a copy
+    L1 = L0 + L0[:k]
+    L2 = [(-1)**(L1[i].to_int() + L1[i + k].to_int()) for i in range(P)]
+    tot = sum(L2)
+    return Rational(tot, P)
+
+
+def lfsr_connection_polynomial(s):
+    """
+    This function computes the LFSR connection polynomial.
+
+    Parameters
+    ==========
+
+    s
+        A sequence of elements of even length, with entries in a finite
+        field.
+
+    Returns
+    =======
+
+    C(x)
+        The connection polynomial of a minimal LFSR yielding s.
+
+        This implements the algorithm in section 3 of J. L. Massey's
+        article [M]_.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import (
+    ...     lfsr_sequence, lfsr_connection_polynomial)
+    >>> from sympy.polys.domains import FF
+    >>> F = FF(2)
+    >>> fill = [F(1), F(1), F(0), F(1)]
+    >>> key = [F(1), F(0), F(0), F(1)]
+    >>> s = lfsr_sequence(key, fill, 20)
+    >>> lfsr_connection_polynomial(s)
+    x**4 + x + 1
+    >>> fill = [F(1), F(0), F(0), F(1)]
+    >>> key = [F(1), F(1), F(0), F(1)]
+    >>> s = lfsr_sequence(key, fill, 20)
+    >>> lfsr_connection_polynomial(s)
+    x**3 + 1
+    >>> fill = [F(1), F(0), F(1)]
+    >>> key = [F(1), F(1), F(0)]
+    >>> s = lfsr_sequence(key, fill, 20)
+    >>> lfsr_connection_polynomial(s)
+    x**3 + x**2 + 1
+    >>> fill = [F(1), F(0), F(1)]
+    >>> key = [F(1), F(0), F(1)]
+    >>> s = lfsr_sequence(key, fill, 20)
+    >>> lfsr_connection_polynomial(s)
+    x**3 + x + 1
+
+    References
+    ==========
+
+    .. [M] James L. Massey, "Shift-Register Synthesis and BCH Decoding."
+        IEEE Trans. on Information Theory, vol. 15(1), pp. 122-127,
+        Jan 1969.
+
+    """
+    # Initialization:
+    p = s[0].mod
+    x = Symbol("x")
+    C = 1*x**0
+    B = 1*x**0
+    m = 1
+    b = 1*x**0
+    L = 0
+    N = 0
+    while N < len(s):
+        if L > 0:
+            dC = Poly(C).degree()
+            r = min(L + 1, dC + 1)
+            coeffsC = [C.subs(x, 0)] + [C.coeff(x**i)
+                for i in range(1, dC + 1)]
+            d = (s[N].to_int() + sum([coeffsC[i]*s[N - i].to_int()
+                for i in range(1, r)])) % p
+        if L == 0:
+            d = s[N].to_int()*x**0
+        if d == 0:
+            m += 1
+            N += 1
+        if d > 0:
+            if 2*L > N:
+                C = (C - d*((b**(p - 2)) % p)*x**m*B).expand()
+                m += 1
+                N += 1
+            else:
+                T = C
+                C = (C - d*((b**(p - 2)) % p)*x**m*B).expand()
+                L = N + 1 - L
+                m = 1
+                b = d
+                B = T
+                N += 1
+    dC = Poly(C).degree()
+    coeffsC = [C.subs(x, 0)] + [C.coeff(x**i) for i in range(1, dC + 1)]
+    return sum([coeffsC[i] % p*x**i for i in range(dC + 1)
+        if coeffsC[i] is not None])
+
+
+#################### ElGamal  #############################
+
+
+def elgamal_private_key(digit=10, seed=None):
+    r"""
+    Return three number tuple as private key.
+
+    Explanation
+    ===========
+
+    Elgamal encryption is based on the mathematical problem
+    called the Discrete Logarithm Problem (DLP). For example,
+
+    `a^{b} \equiv c \pmod p`
+
+    In general, if ``a`` and ``b`` are known, ``ct`` is easily
+    calculated. If ``b`` is unknown, it is hard to use
+    ``a`` and ``ct`` to get ``b``.
+
+    Parameters
+    ==========
+
+    digit : int
+        Minimum number of binary digits for key.
+
+    Returns
+    =======
+
+    tuple : (p, r, d)
+        p = prime number.
+
+        r = primitive root.
+
+        d = random number.
+
+    Notes
+    =====
+
+    For testing purposes, the ``seed`` parameter may be set to control
+    the output of this routine. See sympy.core.random._randrange.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import elgamal_private_key
+    >>> from sympy.ntheory import is_primitive_root, isprime
+    >>> a, b, _ = elgamal_private_key()
+    >>> isprime(a)
+    True
+    >>> is_primitive_root(b, a)
+    True
+
+    """
+    randrange = _randrange(seed)
+    p = nextprime(2**digit)
+    return p, primitive_root(p), randrange(2, p)
+
+
+def elgamal_public_key(key):
+    r"""
+    Return three number tuple as public key.
+
+    Parameters
+    ==========
+
+    key : (p, r, e)
+        Tuple generated by ``elgamal_private_key``.
+
+    Returns
+    =======
+
+    tuple : (p, r, e)
+        `e = r**d \bmod p`
+
+        `d` is a random number in private key.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import elgamal_public_key
+    >>> elgamal_public_key((1031, 14, 636))
+    (1031, 14, 212)
+
+    """
+    p, r, e = key
+    return p, r, pow(r, e, p)
+
+
+def encipher_elgamal(i, key, seed=None):
+    r"""
+    Encrypt message with public key.
+
+    Explanation
+    ===========
+
+    ``i`` is a plaintext message expressed as an integer.
+    ``key`` is public key (p, r, e). In order to encrypt
+    a message, a random number ``a`` in ``range(2, p)``
+    is generated and the encryped message is returned as
+    `c_{1}` and `c_{2}` where:
+
+    `c_{1} \equiv r^{a} \pmod p`
+
+    `c_{2} \equiv m e^{a} \pmod p`
+
+    Parameters
+    ==========
+
+    msg
+        int of encoded message.
+
+    key
+        Public key.
+
+    Returns
+    =======
+
+    tuple : (c1, c2)
+        Encipher into two number.
+
+    Notes
+    =====
+
+    For testing purposes, the ``seed`` parameter may be set to control
+    the output of this routine. See sympy.core.random._randrange.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encipher_elgamal, elgamal_private_key, elgamal_public_key
+    >>> pri = elgamal_private_key(5, seed=[3]); pri
+    (37, 2, 3)
+    >>> pub = elgamal_public_key(pri); pub
+    (37, 2, 8)
+    >>> msg = 36
+    >>> encipher_elgamal(msg, pub, seed=[3])
+    (8, 6)
+
+    """
+    p, r, e = key
+    if i < 0 or i >= p:
+        raise ValueError(
+            'Message (%s) should be in range(%s)' % (i, p))
+    randrange = _randrange(seed)
+    a = randrange(2, p)
+    return pow(r, a, p), i*pow(e, a, p) % p
+
+
+def decipher_elgamal(msg, key):
+    r"""
+    Decrypt message with private key.
+
+    `msg = (c_{1}, c_{2})`
+
+    `key = (p, r, d)`
+
+    According to extended Eucliden theorem,
+    `u c_{1}^{d} + p n = 1`
+
+    `u \equiv 1/{{c_{1}}^d} \pmod p`
+
+    `u c_{2} \equiv \frac{1}{c_{1}^d} c_{2} \equiv \frac{1}{r^{ad}} c_{2} \pmod p`
+
+    `\frac{1}{r^{ad}} m e^a \equiv \frac{1}{r^{ad}} m {r^{d a}} \equiv m \pmod p`
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import decipher_elgamal
+    >>> from sympy.crypto.crypto import encipher_elgamal
+    >>> from sympy.crypto.crypto import elgamal_private_key
+    >>> from sympy.crypto.crypto import elgamal_public_key
+
+    >>> pri = elgamal_private_key(5, seed=[3])
+    >>> pub = elgamal_public_key(pri); pub
+    (37, 2, 8)
+    >>> msg = 17
+    >>> decipher_elgamal(encipher_elgamal(msg, pub), pri) == msg
+    True
+
+    """
+    p, _, d = key
+    c1, c2 = msg
+    u = igcdex(c1**d, p)[0]
+    return u * c2 % p
+
+
+################ Diffie-Hellman Key Exchange  #########################
+
+def dh_private_key(digit=10, seed=None):
+    r"""
+    Return three integer tuple as private key.
+
+    Explanation
+    ===========
+
+    Diffie-Hellman key exchange is based on the mathematical problem
+    called the Discrete Logarithm Problem (see ElGamal).
+
+    Diffie-Hellman key exchange is divided into the following steps:
+
+    *   Alice and Bob agree on a base that consist of a prime ``p``
+        and a primitive root of ``p`` called ``g``
+    *   Alice choses a number ``a`` and Bob choses a number ``b`` where
+        ``a`` and ``b`` are random numbers in range `[2, p)`. These are
+        their private keys.
+    *   Alice then publicly sends Bob `g^{a} \pmod p` while Bob sends
+        Alice `g^{b} \pmod p`
+    *   They both raise the received value to their secretly chosen
+        number (``a`` or ``b``) and now have both as their shared key
+        `g^{ab} \pmod p`
+
+    Parameters
+    ==========
+
+    digit
+        Minimum number of binary digits required in key.
+
+    Returns
+    =======
+
+    tuple : (p, g, a)
+        p = prime number.
+
+        g = primitive root of p.
+
+        a = random number from 2 through p - 1.
+
+    Notes
+    =====
+
+    For testing purposes, the ``seed`` parameter may be set to control
+    the output of this routine. See sympy.core.random._randrange.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import dh_private_key
+    >>> from sympy.ntheory import isprime, is_primitive_root
+    >>> p, g, _ = dh_private_key()
+    >>> isprime(p)
+    True
+    >>> is_primitive_root(g, p)
+    True
+    >>> p, g, _ = dh_private_key(5)
+    >>> isprime(p)
+    True
+    >>> is_primitive_root(g, p)
+    True
+
+    """
+    p = nextprime(2**digit)
+    g = primitive_root(p)
+    randrange = _randrange(seed)
+    a = randrange(2, p)
+    return p, g, a
+
+
+def dh_public_key(key):
+    r"""
+    Return three number tuple as public key.
+
+    This is the tuple that Alice sends to Bob.
+
+    Parameters
+    ==========
+
+    key : (p, g, a)
+        A tuple generated by ``dh_private_key``.
+
+    Returns
+    =======
+
+    tuple : int, int, int
+        A tuple of `(p, g, g^a \mod p)` with `p`, `g` and `a` given as
+        parameters.s
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import dh_private_key, dh_public_key
+    >>> p, g, a = dh_private_key();
+    >>> _p, _g, x = dh_public_key((p, g, a))
+    >>> p == _p and g == _g
+    True
+    >>> x == pow(g, a, p)
+    True
+
+    """
+    p, g, a = key
+    return p, g, pow(g, a, p)
+
+
+def dh_shared_key(key, b):
+    """
+    Return an integer that is the shared key.
+
+    This is what Bob and Alice can both calculate using the public
+    keys they received from each other and their private keys.
+
+    Parameters
+    ==========
+
+    key : (p, g, x)
+        Tuple `(p, g, x)` generated by ``dh_public_key``.
+
+    b
+        Random number in the range of `2` to `p - 1`
+        (Chosen by second key exchange member (Bob)).
+
+    Returns
+    =======
+
+    int
+        A shared key.
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import (
+    ...     dh_private_key, dh_public_key, dh_shared_key)
+    >>> prk = dh_private_key();
+    >>> p, g, x = dh_public_key(prk);
+    >>> sk = dh_shared_key((p, g, x), 1000)
+    >>> sk == pow(x, 1000, p)
+    True
+
+    """
+    p, _, x = key
+    if 1 >= b or b >= p:
+        raise ValueError(filldedent('''
+            Value of b should be greater 1 and less
+            than prime %s.''' % p))
+
+    return pow(x, b, p)
+
+
+################ Goldwasser-Micali Encryption  #########################
+
+
+def _legendre(a, p):
+    """
+    Returns the legendre symbol of a and p
+    assuming that p is a prime.
+
+    i.e. 1 if a is a quadratic residue mod p
+        -1 if a is not a quadratic residue mod p
+         0 if a is divisible by p
+
+    Parameters
+    ==========
+
+    a : int
+        The number to test.
+
+    p : prime
+        The prime to test ``a`` against.
+
+    Returns
+    =======
+
+    int
+        Legendre symbol (a / p).
+
+    """
+    sig = pow(a, (p - 1)//2, p)
+    if sig == 1:
+        return 1
+    elif sig == 0:
+        return 0
+    else:
+        return -1
+
+
+def _random_coprime_stream(n, seed=None):
+    randrange = _randrange(seed)
+    while True:
+        y = randrange(n)
+        if gcd(y, n) == 1:
+            yield y
+
+
+def gm_private_key(p, q, a=None):
+    r"""
+    Check if ``p`` and ``q`` can be used as private keys for
+    the Goldwasser-Micali encryption. The method works
+    roughly as follows.
+
+    Explanation
+    ===========
+
+    #. Pick two large primes $p$ and $q$.
+    #. Call their product $N$.
+    #. Given a message as an integer $i$, write $i$ in its bit representation $b_0, \dots, b_n$.
+    #. For each $k$,
+
+     if $b_k = 0$:
+        let $a_k$ be a random square
+        (quadratic residue) modulo $p q$
+        such that ``jacobi_symbol(a, p*q) = 1``
+     if $b_k = 1$:
+        let $a_k$ be a random non-square
+        (non-quadratic residue) modulo $p q$
+        such that ``jacobi_symbol(a, p*q) = 1``
+
+    returns $\left[a_1, a_2, \dots\right]$
+
+    $b_k$ can be recovered by checking whether or not
+    $a_k$ is a residue. And from the $b_k$'s, the message
+    can be reconstructed.
+
+    The idea is that, while ``jacobi_symbol(a, p*q)``
+    can be easily computed (and when it is equal to $-1$ will
+    tell you that $a$ is not a square mod $p q$), quadratic
+    residuosity modulo a composite number is hard to compute
+    without knowing its factorization.
+
+    Moreover, approximately half the numbers coprime to $p q$ have
+    :func:`~.jacobi_symbol` equal to $1$ . And among those, approximately half
+    are residues and approximately half are not. This maximizes the
+    entropy of the code.
+
+    Parameters
+    ==========
+
+    p, q, a
+        Initialization variables.
+
+    Returns
+    =======
+
+    tuple : (p, q)
+        The input value ``p`` and ``q``.
+
+    Raises
+    ======
+
+    ValueError
+        If ``p`` and ``q`` are not distinct odd primes.
+
+    """
+    if p == q:
+        raise ValueError("expected distinct primes, "
+                         "got two copies of %i" % p)
+    elif not isprime(p) or not isprime(q):
+        raise ValueError("first two arguments must be prime, "
+                         "got %i of %i" % (p, q))
+    elif p == 2 or q == 2:
+        raise ValueError("first two arguments must not be even, "
+                         "got %i of %i" % (p, q))
+    return p, q
+
+
+def gm_public_key(p, q, a=None, seed=None):
+    """
+    Compute public keys for ``p`` and ``q``.
+    Note that in Goldwasser-Micali Encryption,
+    public keys are randomly selected.
+
+    Parameters
+    ==========
+
+    p, q, a : int, int, int
+        Initialization variables.
+
+    Returns
+    =======
+
+    tuple : (a, N)
+        ``a`` is the input ``a`` if it is not ``None`` otherwise
+        some random integer coprime to ``p`` and ``q``.
+
+        ``N`` is the product of ``p`` and ``q``.
+
+    """
+
+    p, q = gm_private_key(p, q)
+    N = p * q
+
+    if a is None:
+        randrange = _randrange(seed)
+        while True:
+            a = randrange(N)
+            if _legendre(a, p) == _legendre(a, q) == -1:
+                break
+    else:
+        if _legendre(a, p) != -1 or _legendre(a, q) != -1:
+            return False
+    return (a, N)
+
+
+def encipher_gm(i, key, seed=None):
+    """
+    Encrypt integer 'i' using public_key 'key'
+    Note that gm uses random encryption.
+
+    Parameters
+    ==========
+
+    i : int
+        The message to encrypt.
+
+    key : (a, N)
+        The public key.
+
+    Returns
+    =======
+
+    list : list of int
+        The randomized encrypted message.
+
+    """
+    if i < 0:
+        raise ValueError(
+            "message must be a non-negative "
+            "integer: got %d instead" % i)
+    a, N = key
+    bits = []
+    while i > 0:
+        bits.append(i % 2)
+        i //= 2
+
+    gen = _random_coprime_stream(N, seed)
+    rev = reversed(bits)
+    encode = lambda b: next(gen)**2*pow(a, b) % N
+    return [ encode(b) for b in rev ]
+
+
+
+def decipher_gm(message, key):
+    """
+    Decrypt message 'message' using public_key 'key'.
+
+    Parameters
+    ==========
+
+    message : list of int
+        The randomized encrypted message.
+
+    key : (p, q)
+        The private key.
+
+    Returns
+    =======
+
+    int
+        The encrypted message.
+
+    """
+    p, q = key
+    res = lambda m, p: _legendre(m, p) > 0
+    bits = [res(m, p) * res(m, q) for m in message]
+    m = 0
+    for b in bits:
+        m <<= 1
+        m += not b
+    return m
+
+
+
+########### RailFence Cipher #############
+
+def encipher_railfence(message,rails):
+    """
+    Performs Railfence Encryption on plaintext and returns ciphertext
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import encipher_railfence
+    >>> message = "hello world"
+    >>> encipher_railfence(message,3)
+    'horel ollwd'
+
+    Parameters
+    ==========
+
+    message : string, the message to encrypt.
+    rails : int, the number of rails.
+
+    Returns
+    =======
+
+    The Encrypted string message.
+
+    References
+    ==========
+    .. [1] https://en.wikipedia.org/wiki/Rail_fence_cipher
+
+    """
+    r = list(range(rails))
+    p = cycle(r + r[-2:0:-1])
+    return ''.join(sorted(message, key=lambda i: next(p)))
+
+
+def decipher_railfence(ciphertext,rails):
+    """
+    Decrypt the message using the given rails
+
+    Examples
+    ========
+
+    >>> from sympy.crypto.crypto import decipher_railfence
+    >>> decipher_railfence("horel ollwd",3)
+    'hello world'
+
+    Parameters
+    ==========
+
+    message : string, the message to encrypt.
+    rails : int, the number of rails.
+
+    Returns
+    =======
+
+    The Decrypted string message.
+
+    """
+    r = list(range(rails))
+    p = cycle(r + r[-2:0:-1])
+
+    idx = sorted(range(len(ciphertext)), key=lambda i: next(p))
+    res = [''] * len(ciphertext)
+    for i, c in zip(idx, ciphertext):
+        res[i] = c
+    return ''.join(res)
+
+
+################ Blum-Goldwasser cryptosystem  #########################
+
+def bg_private_key(p, q):
+    """
+    Check if p and q can be used as private keys for
+    the Blum-Goldwasser cryptosystem.
+
+    Explanation
+    ===========
+
+    The three necessary checks for p and q to pass
+    so that they can be used as private keys:
+
+        1. p and q must both be prime
+        2. p and q must be distinct
+        3. p and q must be congruent to 3 mod 4
+
+    Parameters
+    ==========
+
+    p, q
+        The keys to be checked.
+
+    Returns
+    =======
+
+    p, q
+        Input values.
+
+    Raises
+    ======
+
+    ValueError
+        If p and q do not pass the above conditions.
+
+    """
+
+    if not isprime(p) or not isprime(q):
+        raise ValueError("the two arguments must be prime, "
+                         "got %i and %i" %(p, q))
+    elif p == q:
+        raise ValueError("the two arguments must be distinct, "
+                         "got two copies of %i. " %p)
+    elif (p - 3) % 4 != 0 or (q - 3) % 4 != 0:
+        raise ValueError("the two arguments must be congruent to 3 mod 4, "
+                         "got %i and %i" %(p, q))
+    return p, q
+
+def bg_public_key(p, q):
+    """
+    Calculates public keys from private keys.
+
+    Explanation
+    ===========
+
+    The function first checks the validity of
+    private keys passed as arguments and
+    then returns their product.
+
+    Parameters
+    ==========
+
+    p, q
+        The private keys.
+
+    Returns
+    =======
+
+    N
+        The public key.
+
+    """
+    p, q = bg_private_key(p, q)
+    N = p * q
+    return N
+
+def encipher_bg(i, key, seed=None):
+    """
+    Encrypts the message using public key and seed.
+
+    Explanation
+    ===========
+
+    ALGORITHM:
+        1. Encodes i as a string of L bits, m.
+        2. Select a random element r, where 1 < r < key, and computes
+           x = r^2 mod key.
+        3. Use BBS pseudo-random number generator to generate L random bits, b,
+        using the initial seed as x.
+        4. Encrypted message, c_i = m_i XOR b_i, 1 <= i <= L.
+        5. x_L = x^(2^L) mod key.
+        6. Return (c, x_L)
+
+    Parameters
+    ==========
+
+    i
+        Message, a non-negative integer
+
+    key
+        The public key
+
+    Returns
+    =======
+
+    Tuple
+        (encrypted_message, x_L)
+
+    Raises
+    ======
+
+    ValueError
+        If i is negative.
+
+    """
+
+    if i < 0:
+        raise ValueError(
+            "message must be a non-negative "
+            "integer: got %d instead" % i)
+
+    enc_msg = []
+    while i > 0:
+        enc_msg.append(i % 2)
+        i //= 2
+    enc_msg.reverse()
+    L = len(enc_msg)
+
+    r = _randint(seed)(2, key - 1)
+    x = r**2 % key
+    x_L = pow(int(x), int(2**L), int(key))
+
+    rand_bits = []
+    for _ in range(L):
+        rand_bits.append(x % 2)
+        x = x**2 % key
+
+    encrypt_msg = [m ^ b for (m, b) in zip(enc_msg, rand_bits)]
+
+    return (encrypt_msg, x_L)
+
+def decipher_bg(message, key):
+    """
+    Decrypts the message using private keys.
+
+    Explanation
+    ===========
+
+    ALGORITHM:
+        1. Let, c be the encrypted message, y the second number received,
+        and p and q be the private keys.
+        2. Compute, r_p = y^((p+1)/4 ^ L) mod p and
+        r_q = y^((q+1)/4 ^ L) mod q.
+        3. Compute x_0 = (q(q^-1 mod p)r_p + p(p^-1 mod q)r_q) mod N.
+        4. From, recompute the bits using the BBS generator, as in the
+        encryption algorithm.
+        5. Compute original message by XORing c and b.
+
+    Parameters
+    ==========
+
+    message
+        Tuple of encrypted message and a non-negative integer.
+
+    key
+        Tuple of private keys.
+
+    Returns
+    =======
+
+    orig_msg
+        The original message
+
+    """
+
+    p, q = key
+    encrypt_msg, y = message
+    public_key = p * q
+    L = len(encrypt_msg)
+    p_t = ((p + 1)/4)**L
+    q_t = ((q + 1)/4)**L
+    r_p = pow(int(y), int(p_t), int(p))
+    r_q = pow(int(y), int(q_t), int(q))
+
+    x = (q * mod_inverse(q, p) * r_p + p * mod_inverse(p, q) * r_q) % public_key
+
+    orig_bits = []
+    for _ in range(L):
+        orig_bits.append(x % 2)
+        x = x**2 % public_key
+
+    orig_msg = 0
+    for (m, b) in zip(encrypt_msg, orig_bits):
+        orig_msg = orig_msg * 2
+        orig_msg += (m ^ b)
+
+    return orig_msg

venv/lib/python3.10/site-packages/sympy/crypto/tests/test_crypto.py

@@ -0,0 +1,562 @@
+from sympy.core import symbols
+from sympy.crypto.crypto import (cycle_list,
+      encipher_shift, encipher_affine, encipher_substitution,
+      check_and_join, encipher_vigenere, decipher_vigenere,
+      encipher_hill, decipher_hill, encipher_bifid5, encipher_bifid6,
+      bifid5_square, bifid6_square, bifid5, bifid6,
+      decipher_bifid5, decipher_bifid6, encipher_kid_rsa,
+      decipher_kid_rsa, kid_rsa_private_key, kid_rsa_public_key,
+      decipher_rsa, rsa_private_key, rsa_public_key, encipher_rsa,
+      lfsr_connection_polynomial, lfsr_autocorrelation, lfsr_sequence,
+      encode_morse, decode_morse, elgamal_private_key, elgamal_public_key,
+      encipher_elgamal, decipher_elgamal, dh_private_key, dh_public_key,
+      dh_shared_key, decipher_shift, decipher_affine, encipher_bifid,
+      decipher_bifid, bifid_square, padded_key, uniq, decipher_gm,
+      encipher_gm, gm_public_key, gm_private_key, encipher_bg, decipher_bg,
+      bg_private_key, bg_public_key, encipher_rot13, decipher_rot13,
+      encipher_atbash, decipher_atbash, NonInvertibleCipherWarning,
+      encipher_railfence, decipher_railfence)
+from sympy.matrices import Matrix
+from sympy.ntheory import isprime, is_primitive_root
+from sympy.polys.domains import FF
+
+from sympy.testing.pytest import raises, warns
+
+from sympy.core.random import randrange
+
+def test_encipher_railfence():
+    assert encipher_railfence("hello world",2) == "hlowrdel ol"
+    assert encipher_railfence("hello world",3) == "horel ollwd"
+    assert encipher_railfence("hello world",4) == "hwe olordll"
+
+def test_decipher_railfence():
+    assert decipher_railfence("hlowrdel ol",2) == "hello world"
+    assert decipher_railfence("horel ollwd",3) == "hello world"
+    assert decipher_railfence("hwe olordll",4) == "hello world"
+
+
+def test_cycle_list():
+    assert cycle_list(3, 4) == [3, 0, 1, 2]
+    assert cycle_list(-1, 4) == [3, 0, 1, 2]
+    assert cycle_list(1, 4) == [1, 2, 3, 0]
+
+
+def test_encipher_shift():
+    assert encipher_shift("ABC", 0) == "ABC"
+    assert encipher_shift("ABC", 1) == "BCD"
+    assert encipher_shift("ABC", -1) == "ZAB"
+    assert decipher_shift("ZAB", -1) == "ABC"
+
+def test_encipher_rot13():
+    assert encipher_rot13("ABC") == "NOP"
+    assert encipher_rot13("NOP") == "ABC"
+    assert decipher_rot13("ABC") == "NOP"
+    assert decipher_rot13("NOP") == "ABC"
+
+
+def test_encipher_affine():
+    assert encipher_affine("ABC", (1, 0)) == "ABC"
+    assert encipher_affine("ABC", (1, 1)) == "BCD"
+    assert encipher_affine("ABC", (-1, 0)) == "AZY"
+    assert encipher_affine("ABC", (-1, 1), symbols="ABCD") == "BAD"
+    assert encipher_affine("123", (-1, 1), symbols="1234") == "214"
+    assert encipher_affine("ABC", (3, 16)) == "QTW"
+    assert decipher_affine("QTW", (3, 16)) == "ABC"
+
+def test_encipher_atbash():
+    assert encipher_atbash("ABC") == "ZYX"
+    assert encipher_atbash("ZYX") == "ABC"
+    assert decipher_atbash("ABC") == "ZYX"
+    assert decipher_atbash("ZYX") == "ABC"
+
+def test_encipher_substitution():
+    assert encipher_substitution("ABC", "BAC", "ABC") == "BAC"
+    assert encipher_substitution("123", "1243", "1234") == "124"
+
+
+def test_check_and_join():
+    assert check_and_join("abc") == "abc"
+    assert check_and_join(uniq("aaabc")) == "abc"
+    assert check_and_join("ab c".split()) == "abc"
+    assert check_and_join("abc", "a", filter=True) == "a"
+    raises(ValueError, lambda: check_and_join('ab', 'a'))
+
+
+def test_encipher_vigenere():
+    assert encipher_vigenere("ABC", "ABC") == "ACE"
+    assert encipher_vigenere("ABC", "ABC", symbols="ABCD") == "ACA"
+    assert encipher_vigenere("ABC", "AB", symbols="ABCD") == "ACC"
+    assert encipher_vigenere("AB", "ABC", symbols="ABCD") == "AC"
+    assert encipher_vigenere("A", "ABC", symbols="ABCD") == "A"
+
+
+def test_decipher_vigenere():
+    assert decipher_vigenere("ABC", "ABC") == "AAA"
+    assert decipher_vigenere("ABC", "ABC", symbols="ABCD") == "AAA"
+    assert decipher_vigenere("ABC", "AB", symbols="ABCD") == "AAC"
+    assert decipher_vigenere("AB", "ABC", symbols="ABCD") == "AA"
+    assert decipher_vigenere("A", "ABC", symbols="ABCD") == "A"
+
+
+def test_encipher_hill():
+    A = Matrix(2, 2, [1, 2, 3, 5])
+    assert encipher_hill("ABCD", A) == "CFIV"
+    A = Matrix(2, 2, [1, 0, 0, 1])
+    assert encipher_hill("ABCD", A) == "ABCD"
+    assert encipher_hill("ABCD", A, symbols="ABCD") == "ABCD"
+    A = Matrix(2, 2, [1, 2, 3, 5])
+    assert encipher_hill("ABCD", A, symbols="ABCD") == "CBAB"
+    assert encipher_hill("AB", A, symbols="ABCD") == "CB"
+    # message length, n, does not need to be a multiple of k;
+    # it is padded
+    assert encipher_hill("ABA", A) == "CFGC"
+    assert encipher_hill("ABA", A, pad="Z") == "CFYV"
+
+
+def test_decipher_hill():
+    A = Matrix(2, 2, [1, 2, 3, 5])
+    assert decipher_hill("CFIV", A) == "ABCD"
+    A = Matrix(2, 2, [1, 0, 0, 1])
+    assert decipher_hill("ABCD", A) == "ABCD"
+    assert decipher_hill("ABCD", A, symbols="ABCD") == "ABCD"
+    A = Matrix(2, 2, [1, 2, 3, 5])
+    assert decipher_hill("CBAB", A, symbols="ABCD") == "ABCD"
+    assert decipher_hill("CB", A, symbols="ABCD") == "AB"
+    # n does not need to be a multiple of k
+    assert decipher_hill("CFA", A) == "ABAA"
+
+
+def test_encipher_bifid5():
+    assert encipher_bifid5("AB", "AB") == "AB"
+    assert encipher_bifid5("AB", "CD") == "CO"
+    assert encipher_bifid5("ab", "c") == "CH"
+    assert encipher_bifid5("a bc", "b") == "BAC"
+
+
+def test_bifid5_square():
+    A = bifid5
+    f = lambda i, j: symbols(A[5*i + j])
+    M = Matrix(5, 5, f)
+    assert bifid5_square("") == M
+
+
+def test_decipher_bifid5():
+    assert decipher_bifid5("AB", "AB") == "AB"
+    assert decipher_bifid5("CO", "CD") == "AB"
+    assert decipher_bifid5("ch", "c") == "AB"
+    assert decipher_bifid5("b ac", "b") == "ABC"
+
+
+def test_encipher_bifid6():
+    assert encipher_bifid6("AB", "AB") == "AB"
+    assert encipher_bifid6("AB", "CD") == "CP"
+    assert encipher_bifid6("ab", "c") == "CI"
+    assert encipher_bifid6("a bc", "b") == "BAC"
+
+
+def test_decipher_bifid6():
+    assert decipher_bifid6("AB", "AB") == "AB"
+    assert decipher_bifid6("CP", "CD") == "AB"
+    assert decipher_bifid6("ci", "c") == "AB"
+    assert decipher_bifid6("b ac", "b") == "ABC"
+
+
+def test_bifid6_square():
+    A = bifid6
+    f = lambda i, j: symbols(A[6*i + j])
+    M = Matrix(6, 6, f)
+    assert bifid6_square("") == M
+
+
+def test_rsa_public_key():
+    assert rsa_public_key(2, 3, 1) == (6, 1)
+    assert rsa_public_key(5, 3, 3) == (15, 3)
+
+    with warns(NonInvertibleCipherWarning):
+        assert rsa_public_key(2, 2, 1) == (4, 1)
+        assert rsa_public_key(8, 8, 8) is False
+
+
+def test_rsa_private_key():
+    assert rsa_private_key(2, 3, 1) == (6, 1)
+    assert rsa_private_key(5, 3, 3) == (15, 3)
+    assert rsa_private_key(23,29,5) == (667,493)
+
+    with warns(NonInvertibleCipherWarning):
+        assert rsa_private_key(2, 2, 1) == (4, 1)
+        assert rsa_private_key(8, 8, 8) is False
+
+
+def test_rsa_large_key():
+    # Sample from
+    # http://www.herongyang.com/Cryptography/JCE-Public-Key-RSA-Private-Public-Key-Pair-Sample.html
+    p = int('101565610013301240713207239558950144682174355406589305284428666'\
+        '903702505233009')
+    q = int('894687191887545488935455605955948413812376003053143521429242133'\
+        '12069293984003')
+    e = int('65537')
+    d = int('893650581832704239530398858744759129594796235440844479456143566'\
+        '6999402846577625762582824202269399672579058991442587406384754958587'\
+        '400493169361356902030209')
+    assert rsa_public_key(p, q, e) == (p*q, e)
+    assert rsa_private_key(p, q, e) == (p*q, d)
+
+
+def test_encipher_rsa():
+    puk = rsa_public_key(2, 3, 1)
+    assert encipher_rsa(2, puk) == 2
+    puk = rsa_public_key(5, 3, 3)
+    assert encipher_rsa(2, puk) == 8
+
+    with warns(NonInvertibleCipherWarning):
+        puk = rsa_public_key(2, 2, 1)
+        assert encipher_rsa(2, puk) == 2
+
+
+def test_decipher_rsa():
+    prk = rsa_private_key(2, 3, 1)
+    assert decipher_rsa(2, prk) == 2
+    prk = rsa_private_key(5, 3, 3)
+    assert decipher_rsa(8, prk) == 2
+
+    with warns(NonInvertibleCipherWarning):
+        prk = rsa_private_key(2, 2, 1)
+        assert decipher_rsa(2, prk) == 2
+
+
+def test_mutltiprime_rsa_full_example():
+    # Test example from
+    # https://iopscience.iop.org/article/10.1088/1742-6596/995/1/012030
+    puk = rsa_public_key(2, 3, 5, 7, 11, 13, 7)
+    prk = rsa_private_key(2, 3, 5, 7, 11, 13, 7)
+    assert puk == (30030, 7)
+    assert prk == (30030, 823)
+
+    msg = 10
+    encrypted = encipher_rsa(2 * msg - 15, puk)
+    assert encrypted == 18065
+    decrypted = (decipher_rsa(encrypted, prk) + 15) / 2
+    assert decrypted == msg
+
+    # Test example from
+    # https://www.scirp.org/pdf/JCC_2018032215502008.pdf
+    puk1 = rsa_public_key(53, 41, 43, 47, 41)
+    prk1 = rsa_private_key(53, 41, 43, 47, 41)
+    puk2 = rsa_public_key(53, 41, 43, 47, 97)
+    prk2 = rsa_private_key(53, 41, 43, 47, 97)
+
+    assert puk1 == (4391633, 41)
+    assert prk1 == (4391633, 294041)
+    assert puk2 == (4391633, 97)
+    assert prk2 == (4391633, 455713)
+
+    msg = 12321
+    encrypted = encipher_rsa(encipher_rsa(msg, puk1), puk2)
+    assert encrypted == 1081588
+    decrypted = decipher_rsa(decipher_rsa(encrypted, prk2), prk1)
+    assert decrypted == msg
+
+
+def test_rsa_crt_extreme():
+    p = int(
+        '10177157607154245068023861503693082120906487143725062283406501' \
+        '54082258226204046999838297167140821364638180697194879500245557' \
+        '65445186962893346463841419427008800341257468600224049986260471' \
+        '92257248163014468841725476918639415726709736077813632961290911' \
+        '0256421232977833028677441206049309220354796014376698325101693')
+
+    q = int(
+        '28752342353095132872290181526607275886182793241660805077850801' \
+        '75689512797754286972952273553128181861830576836289738668745250' \
+        '34028199691128870676414118458442900035778874482624765513861643' \
+        '27966696316822188398336199002306588703902894100476186823849595' \
+        '103239410527279605442148285816149368667083114802852804976893')
+
+    r = int(
+        '17698229259868825776879500736350186838850961935956310134378261' \
+        '89771862186717463067541369694816245225291921138038800171125596' \
+        '07315449521981157084370187887650624061033066022458512942411841' \
+        '18747893789972315277160085086164119879536041875335384844820566' \
+        '0287479617671726408053319619892052000850883994343378882717849')
+
+    s = int(
+        '68925428438585431029269182233502611027091755064643742383515623' \
+        '64321310582896893395529367074942808353187138794422745718419645' \
+        '28291231865157212604266903677599180789896916456120289112752835' \
+        '98502265889669730331688206825220074713977607415178738015831030' \
+        '364290585369150502819743827343552098197095520550865360159439'
+    )
+
+    t = int(
+        '69035483433453632820551311892368908779778144568711455301541094' \
+        '31487047642322695357696860925747923189635033183069823820910521' \
+        '71172909106797748883261493224162414050106920442445896819806600' \
+        '15448444826108008217972129130625571421904893252804729877353352' \
+        '739420480574842850202181462656251626522910618936534699566291'
+    )
+
+    e = 65537
+    puk = rsa_public_key(p, q, r, s, t, e)
+    prk = rsa_private_key(p, q, r, s, t, e)
+
+    plaintext = 1000
+    ciphertext_1 = encipher_rsa(plaintext, puk)
+    ciphertext_2 = encipher_rsa(plaintext, puk, [p, q, r, s, t])
+    assert ciphertext_1 == ciphertext_2
+    assert decipher_rsa(ciphertext_1, prk) == \
+        decipher_rsa(ciphertext_1, prk, [p, q, r, s, t])
+
+
+def test_rsa_exhaustive():
+    p, q = 61, 53
+    e = 17
+    puk = rsa_public_key(p, q, e, totient='Carmichael')
+    prk = rsa_private_key(p, q, e, totient='Carmichael')
+
+    for msg in range(puk[0]):
+        encrypted = encipher_rsa(msg, puk)
+        decrypted = decipher_rsa(encrypted, prk)
+        try:
+            assert decrypted == msg
+        except AssertionError:
+            raise AssertionError(
+                "The RSA is not correctly decrypted " \
+                "(Original : {}, Encrypted : {}, Decrypted : {})" \
+                .format(msg, encrypted, decrypted)
+                )
+
+
+def test_rsa_multiprime_exhanstive():
+    primes = [3, 5, 7, 11]
+    e = 7
+    args = primes + [e]
+    puk = rsa_public_key(*args, totient='Carmichael')
+    prk = rsa_private_key(*args, totient='Carmichael')
+    n = puk[0]
+
+    for msg in range(n):
+        encrypted = encipher_rsa(msg, puk)
+        decrypted = decipher_rsa(encrypted, prk)
+        try:
+            assert decrypted == msg
+        except AssertionError:
+            raise AssertionError(
+                "The RSA is not correctly decrypted " \
+                "(Original : {}, Encrypted : {}, Decrypted : {})" \
+                .format(msg, encrypted, decrypted)
+                )
+
+
+def test_rsa_multipower_exhanstive():
+    from sympy.core.numbers import igcd
+    primes = [5, 5, 7]
+    e = 7
+    args = primes + [e]
+    puk = rsa_public_key(*args, multipower=True)
+    prk = rsa_private_key(*args, multipower=True)
+    n = puk[0]
+
+    for msg in range(n):
+        if igcd(msg, n) != 1:
+            continue
+
+        encrypted = encipher_rsa(msg, puk)
+        decrypted = decipher_rsa(encrypted, prk)
+        try:
+            assert decrypted == msg
+        except AssertionError:
+            raise AssertionError(
+                "The RSA is not correctly decrypted " \
+                "(Original : {}, Encrypted : {}, Decrypted : {})" \
+                .format(msg, encrypted, decrypted)
+                )
+
+
+def test_kid_rsa_public_key():
+    assert kid_rsa_public_key(1, 2, 1, 1) == (5, 2)
+    assert kid_rsa_public_key(1, 2, 2, 1) == (8, 3)
+    assert kid_rsa_public_key(1, 2, 1, 2) == (7, 2)
+
+
+def test_kid_rsa_private_key():
+    assert kid_rsa_private_key(1, 2, 1, 1) == (5, 3)
+    assert kid_rsa_private_key(1, 2, 2, 1) == (8, 3)
+    assert kid_rsa_private_key(1, 2, 1, 2) == (7, 4)
+
+
+def test_encipher_kid_rsa():
+    assert encipher_kid_rsa(1, (5, 2)) == 2
+    assert encipher_kid_rsa(1, (8, 3)) == 3
+    assert encipher_kid_rsa(1, (7, 2)) == 2
+
+
+def test_decipher_kid_rsa():
+    assert decipher_kid_rsa(2, (5, 3)) == 1
+    assert decipher_kid_rsa(3, (8, 3)) == 1
+    assert decipher_kid_rsa(2, (7, 4)) == 1
+
+
+def test_encode_morse():
+    assert encode_morse('ABC') == '.-|-...|-.-.'
+    assert encode_morse('SMS ') == '...|--|...||'
+    assert encode_morse('SMS\n') == '...|--|...||'
+    assert encode_morse('') == ''
+    assert encode_morse(' ') == '||'
+    assert encode_morse(' ', sep='`') == '``'
+    assert encode_morse(' ', sep='``') == '````'
+    assert encode_morse('!@#$%^&*()_+') == '-.-.--|.--.-.|...-..-|-.--.|-.--.-|..--.-|.-.-.'
+    assert encode_morse('12345') == '.----|..---|...--|....-|.....'
+    assert encode_morse('67890') == '-....|--...|---..|----.|-----'
+
+
+def test_decode_morse():
+    assert decode_morse('-.-|.|-.--') == 'KEY'
+    assert decode_morse('.-.|..-|-.||') == 'RUN'
+    raises(KeyError, lambda: decode_morse('.....----'))
+
+
+def test_lfsr_sequence():
+    raises(TypeError, lambda: lfsr_sequence(1, [1], 1))
+    raises(TypeError, lambda: lfsr_sequence([1], 1, 1))
+    F = FF(2)
+    assert lfsr_sequence([F(1)], [F(1)], 2) == [F(1), F(1)]
+    assert lfsr_sequence([F(0)], [F(1)], 2) == [F(1), F(0)]
+    F = FF(3)
+    assert lfsr_sequence([F(1)], [F(1)], 2) == [F(1), F(1)]
+    assert lfsr_sequence([F(0)], [F(2)], 2) == [F(2), F(0)]
+    assert lfsr_sequence([F(1)], [F(2)], 2) == [F(2), F(2)]
+
+
+def test_lfsr_autocorrelation():
+    raises(TypeError, lambda: lfsr_autocorrelation(1, 2, 3))
+    F = FF(2)
+    s = lfsr_sequence([F(1), F(0)], [F(0), F(1)], 5)
+    assert lfsr_autocorrelation(s, 2, 0) == 1
+    assert lfsr_autocorrelation(s, 2, 1) == -1
+
+
+def test_lfsr_connection_polynomial():
+    F = FF(2)
+    x = symbols("x")
+    s = lfsr_sequence([F(1), F(0)], [F(0), F(1)], 5)
+    assert lfsr_connection_polynomial(s) == x**2 + 1
+    s = lfsr_sequence([F(1), F(1)], [F(0), F(1)], 5)
+    assert lfsr_connection_polynomial(s) == x**2 + x + 1
+
+
+def test_elgamal_private_key():
+    a, b, _ = elgamal_private_key(digit=100)
+    assert isprime(a)
+    assert is_primitive_root(b, a)
+    assert len(bin(a)) >= 102
+
+
+def test_elgamal():
+    dk = elgamal_private_key(5)
+    ek = elgamal_public_key(dk)
+    P = ek[0]
+    assert P - 1 == decipher_elgamal(encipher_elgamal(P - 1, ek), dk)
+    raises(ValueError, lambda: encipher_elgamal(P, dk))
+    raises(ValueError, lambda: encipher_elgamal(-1, dk))
+
+
+def test_dh_private_key():
+    p, g, _ = dh_private_key(digit = 100)
+    assert isprime(p)
+    assert is_primitive_root(g, p)
+    assert len(bin(p)) >= 102
+
+
+def test_dh_public_key():
+    p1, g1, a = dh_private_key(digit = 100)
+    p2, g2, ga = dh_public_key((p1, g1, a))
+    assert p1 == p2
+    assert g1 == g2
+    assert ga == pow(g1, a, p1)
+
+
+def test_dh_shared_key():
+    prk = dh_private_key(digit = 100)
+    p, _, ga = dh_public_key(prk)
+    b = randrange(2, p)
+    sk = dh_shared_key((p, _, ga), b)
+    assert sk == pow(ga, b, p)
+    raises(ValueError, lambda: dh_shared_key((1031, 14, 565), 2000))
+
+
+def test_padded_key():
+    assert padded_key('b', 'ab') == 'ba'
+    raises(ValueError, lambda: padded_key('ab', 'ace'))
+    raises(ValueError, lambda: padded_key('ab', 'abba'))
+
+
+def test_bifid():
+    raises(ValueError, lambda: encipher_bifid('abc', 'b', 'abcde'))
+    assert encipher_bifid('abc', 'b', 'abcd') == 'bdb'
+    raises(ValueError, lambda: decipher_bifid('bdb', 'b', 'abcde'))
+    assert encipher_bifid('bdb', 'b', 'abcd') == 'abc'
+    raises(ValueError, lambda: bifid_square('abcde'))
+    assert bifid5_square("B") == \
+        bifid5_square('BACDEFGHIKLMNOPQRSTUVWXYZ')
+    assert bifid6_square('B0') == \
+        bifid6_square('B0ACDEFGHIJKLMNOPQRSTUVWXYZ123456789')
+
+
+def test_encipher_decipher_gm():
+    ps = [131, 137, 139, 149, 151, 157, 163, 167,
+          173, 179, 181, 191, 193, 197, 199]
+    qs = [89, 97, 101, 103, 107, 109, 113, 127,
+          131, 137, 139, 149, 151, 157, 47]
+    messages = [
+        0, 32855, 34303, 14805, 1280, 75859, 38368,
+        724, 60356, 51675, 76697, 61854, 18661,
+    ]
+    for p, q in zip(ps, qs):
+        pri = gm_private_key(p, q)
+        for msg in messages:
+            pub = gm_public_key(p, q)
+            enc = encipher_gm(msg, pub)
+            dec = decipher_gm(enc, pri)
+            assert dec == msg
+
+
+def test_gm_private_key():
+    raises(ValueError, lambda: gm_public_key(13, 15))
+    raises(ValueError, lambda: gm_public_key(0, 0))
+    raises(ValueError, lambda: gm_public_key(0, 5))
+    assert 17, 19 == gm_public_key(17, 19)
+
+
+def test_gm_public_key():
+    assert 323 == gm_public_key(17, 19)[1]
+    assert 15  == gm_public_key(3, 5)[1]
+    raises(ValueError, lambda: gm_public_key(15, 19))
+
+def test_encipher_decipher_bg():
+    ps = [67, 7, 71, 103, 11, 43, 107, 47,
+          79, 19, 83, 23, 59, 127, 31]
+    qs = qs = [7, 71, 103, 11, 43, 107, 47,
+               79, 19, 83, 23, 59, 127, 31, 67]
+    messages = [
+        0, 328, 343, 148, 1280, 758, 383,
+        724, 603, 516, 766, 618, 186,
+    ]
+
+    for p, q in zip(ps, qs):
+        pri = bg_private_key(p, q)
+        for msg in messages:
+            pub = bg_public_key(p, q)
+            enc = encipher_bg(msg, pub)
+            dec = decipher_bg(enc, pri)
+            assert dec == msg
+
+def test_bg_private_key():
+    raises(ValueError, lambda: bg_private_key(8, 16))
+    raises(ValueError, lambda: bg_private_key(8, 8))
+    raises(ValueError, lambda: bg_private_key(13, 17))
+    assert 23, 31 == bg_private_key(23, 31)
+
+def test_bg_public_key():
+    assert 5293 == bg_public_key(67, 79)
+    assert 713 == bg_public_key(23, 31)
+    raises(ValueError, lambda: bg_private_key(13, 17))

venv/lib/python3.10/site-packages/sympy/sets/__init__.py

@@ -0,0 +1,36 @@
+from .sets import (Set, Interval, Union, FiniteSet, ProductSet,
+        Intersection, imageset, Complement, SymmetricDifference,
+        DisjointUnion)
+
+from .fancysets import ImageSet, Range, ComplexRegion
+from .contains import Contains
+from .conditionset import ConditionSet
+from .ordinals import Ordinal, OmegaPower, ord0
+from .powerset import PowerSet
+from ..core.singleton import S
+from .handlers.comparison import _eval_is_eq  # noqa:F401
+Complexes = S.Complexes
+EmptySet = S.EmptySet
+Integers = S.Integers
+Naturals = S.Naturals
+Naturals0 = S.Naturals0
+Rationals = S.Rationals
+Reals = S.Reals
+UniversalSet = S.UniversalSet
+
+__all__ = [
+    'Set', 'Interval', 'Union', 'EmptySet', 'FiniteSet', 'ProductSet',
+    'Intersection', 'imageset', 'Complement', 'SymmetricDifference', 'DisjointUnion',
+
+    'ImageSet', 'Range', 'ComplexRegion', 'Reals',
+
+    'Contains',
+
+    'ConditionSet',
+
+    'Ordinal', 'OmegaPower', 'ord0',
+
+    'PowerSet',
+
+    'Reals', 'Naturals', 'Naturals0', 'UniversalSet', 'Integers', 'Rationals',
+]

venv/lib/python3.10/site-packages/sympy/sets/conditionset.py

@@ -0,0 +1,246 @@
+from sympy.core.singleton import S
+from sympy.core.basic import Basic
+from sympy.core.containers import Tuple
+from sympy.core.function import Lambda, BadSignatureError
+from sympy.core.logic import fuzzy_bool
+from sympy.core.relational import Eq
+from sympy.core.symbol import Dummy
+from sympy.core.sympify import _sympify
+from sympy.logic.boolalg import And, as_Boolean
+from sympy.utilities.iterables import sift, flatten, has_dups
+from sympy.utilities.exceptions import sympy_deprecation_warning
+from .contains import Contains
+from .sets import Set, Union, FiniteSet, SetKind
+
+
+adummy = Dummy('conditionset')
+
+
+class ConditionSet(Set):
+    r"""
+    Set of elements which satisfies a given condition.
+
+    .. math:: \{x \mid \textrm{condition}(x) = \texttt{True}, x \in S\}
+
+    Examples
+    ========
+
+    >>> from sympy import Symbol, S, ConditionSet, pi, Eq, sin, Interval
+    >>> from sympy.abc import x, y, z
+
+    >>> sin_sols = ConditionSet(x, Eq(sin(x), 0), Interval(0, 2*pi))
+    >>> 2*pi in sin_sols
+    True
+    >>> pi/2 in sin_sols
+    False
+    >>> 3*pi in sin_sols
+    False
+    >>> 5 in ConditionSet(x, x**2 > 4, S.Reals)
+    True
+
+    If the value is not in the base set, the result is false:
+
+    >>> 5 in ConditionSet(x, x**2 > 4, Interval(2, 4))
+    False
+
+    Notes
+    =====
+
+    Symbols with assumptions should be avoided or else the
+    condition may evaluate without consideration of the set:
+
+    >>> n = Symbol('n', negative=True)
+    >>> cond = (n > 0); cond
+    False
+    >>> ConditionSet(n, cond, S.Integers)
+    EmptySet
+
+    Only free symbols can be changed by using `subs`:
+
+    >>> c = ConditionSet(x, x < 1, {x, z})
+    >>> c.subs(x, y)
+    ConditionSet(x, x < 1, {y, z})
+
+    To check if ``pi`` is in ``c`` use:
+
+    >>> pi in c
+    False
+
+    If no base set is specified, the universal set is implied:
+
+    >>> ConditionSet(x, x < 1).base_set
+    UniversalSet
+
+    Only symbols or symbol-like expressions can be used:
+
+    >>> ConditionSet(x + 1, x + 1 < 1, S.Integers)
+    Traceback (most recent call last):
+    ...
+    ValueError: non-symbol dummy not recognized in condition
+
+    When the base set is a ConditionSet, the symbols will be
+    unified if possible with preference for the outermost symbols:
+
+    >>> ConditionSet(x, x < y, ConditionSet(z, z + y < 2, S.Integers))
+    ConditionSet(x, (x < y) & (x + y < 2), Integers)
+
+    """
+    def __new__(cls, sym, condition, base_set=S.UniversalSet):
+        sym = _sympify(sym)
+        flat = flatten([sym])
+        if has_dups(flat):
+            raise BadSignatureError("Duplicate symbols detected")
+        base_set = _sympify(base_set)
+        if not isinstance(base_set, Set):
+            raise TypeError(
+                'base set should be a Set object, not %s' % base_set)
+        condition = _sympify(condition)
+
+        if isinstance(condition, FiniteSet):
+            condition_orig = condition
+            temp = (Eq(lhs, 0) for lhs in condition)
+            condition = And(*temp)
+            sympy_deprecation_warning(
+                f"""
+Using a set for the condition in ConditionSet is deprecated. Use a boolean
+instead.
+
+In this case, replace
+
+    {condition_orig}
+
+with
+
+    {condition}
+""",
+                deprecated_since_version='1.5',
+                active_deprecations_target="deprecated-conditionset-set",
+                )
+
+        condition = as_Boolean(condition)
+
+        if condition is S.true:
+            return base_set
+
+        if condition is S.false:
+            return S.EmptySet
+
+        if base_set is S.EmptySet:
+            return S.EmptySet
+
+        # no simple answers, so now check syms
+        for i in flat:
+            if not getattr(i, '_diff_wrt', False):
+                raise ValueError('`%s` is not symbol-like' % i)
+
+        if base_set.contains(sym) is S.false:
+            raise TypeError('sym `%s` is not in base_set `%s`' % (sym, base_set))
+
+        know = None
+        if isinstance(base_set, FiniteSet):
+            sifted = sift(
+                base_set, lambda _: fuzzy_bool(condition.subs(sym, _)))
+            if sifted[None]:
+                know = FiniteSet(*sifted[True])
+                base_set = FiniteSet(*sifted[None])
+            else:
+                return FiniteSet(*sifted[True])
+
+        if isinstance(base_set, cls):
+            s, c, b = base_set.args
+            def sig(s):
+                return cls(s, Eq(adummy, 0)).as_dummy().sym
+            sa, sb = map(sig, (sym, s))
+            if sa != sb:
+                raise BadSignatureError('sym does not match sym of base set')
+            reps = dict(zip(flatten([sym]), flatten([s])))
+            if s == sym:
+                condition = And(condition, c)
+                base_set = b
+            elif not c.free_symbols & sym.free_symbols:
+                reps = {v: k for k, v in reps.items()}
+                condition = And(condition, c.xreplace(reps))
+                base_set = b
+            elif not condition.free_symbols & s.free_symbols:
+                sym = sym.xreplace(reps)
+                condition = And(condition.xreplace(reps), c)
+                base_set = b
+
+        # flatten ConditionSet(Contains(ConditionSet())) expressions
+        if isinstance(condition, Contains) and (sym == condition.args[0]):
+            if isinstance(condition.args[1], Set):
+                return condition.args[1].intersect(base_set)
+
+        rv = Basic.__new__(cls, sym, condition, base_set)
+        return rv if know is None else Union(know, rv)
+
+    sym = property(lambda self: self.args[0])
+    condition = property(lambda self: self.args[1])
+    base_set = property(lambda self: self.args[2])
+
+    @property
+    def free_symbols(self):
+        cond_syms = self.condition.free_symbols - self.sym.free_symbols
+        return cond_syms | self.base_set.free_symbols
+
+    @property
+    def bound_symbols(self):
+        return flatten([self.sym])
+
+    def _contains(self, other):
+        def ok_sig(a, b):
+            tuples = [isinstance(i, Tuple) for i in (a, b)]
+            c = tuples.count(True)
+            if c == 1:
+                return False
+            if c == 0:
+                return True
+            return len(a) == len(b) and all(
+                ok_sig(i, j) for i, j in zip(a, b))
+        if not ok_sig(self.sym, other):
+            return S.false
+
+        # try doing base_cond first and return
+        # False immediately if it is False
+        base_cond = Contains(other, self.base_set)
+        if base_cond is S.false:
+            return S.false
+
+        # Substitute other into condition. This could raise e.g. for
+        # ConditionSet(x, 1/x >= 0, Reals).contains(0)
+        lamda = Lambda((self.sym,), self.condition)
+        try:
+            lambda_cond = lamda(other)
+        except TypeError:
+            return Contains(other, self, evaluate=False)
+        else:
+            return And(base_cond, lambda_cond)
+
+    def as_relational(self, other):
+        f = Lambda(self.sym, self.condition)
+        if isinstance(self.sym, Tuple):
+            f = f(*other)
+        else:
+            f = f(other)
+        return And(f, self.base_set.contains(other))
+
+    def _eval_subs(self, old, new):
+        sym, cond, base = self.args
+        dsym = sym.subs(old, adummy)
+        insym = dsym.has(adummy)
+        # prioritize changing a symbol in the base
+        newbase = base.subs(old, new)
+        if newbase != base:
+            if not insym:
+                cond = cond.subs(old, new)
+            return self.func(sym, cond, newbase)
+        if insym:
+            pass  # no change of bound symbols via subs
+        elif getattr(new, '_diff_wrt', False):
+            cond = cond.subs(old, new)
+        else:
+            pass  # let error about the symbol raise from __new__
+        return self.func(sym, cond, base)
+
+    def _kind(self):
+        return SetKind(self.sym.kind)

venv/lib/python3.10/site-packages/sympy/sets/contains.py

@@ -0,0 +1,48 @@
+from sympy.core import S
+from sympy.core.relational import Eq, Ne
+from sympy.logic.boolalg import BooleanFunction
+from sympy.utilities.misc import func_name
+from .sets import Set
+
+
+class Contains(BooleanFunction):
+    """
+    Asserts that x is an element of the set S.
+
+    Examples
+    ========
+
+    >>> from sympy import Symbol, Integer, S, Contains
+    >>> Contains(Integer(2), S.Integers)
+    True
+    >>> Contains(Integer(-2), S.Naturals)
+    False
+    >>> i = Symbol('i', integer=True)
+    >>> Contains(i, S.Naturals)
+    Contains(i, Naturals)
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Element_%28mathematics%29
+    """
+    @classmethod
+    def eval(cls, x, s):
+
+        if not isinstance(s, Set):
+            raise TypeError('expecting Set, not %s' % func_name(s))
+
+        ret = s.contains(x)
+        if not isinstance(ret, Contains) and (
+                ret in (S.true, S.false) or isinstance(ret, Set)):
+            return ret
+
+    @property
+    def binary_symbols(self):
+        return set().union(*[i.binary_symbols
+            for i in self.args[1].args
+            if i.is_Boolean or i.is_Symbol or
+            isinstance(i, (Eq, Ne))])
+
+    def as_set(self):
+        return self.args[1]

venv/lib/python3.10/site-packages/sympy/sets/fancysets.py

@@ -0,0 +1,1521 @@
+from functools import reduce
+from itertools import product
+
+from sympy.core.basic import Basic
+from sympy.core.containers import Tuple
+from sympy.core.expr import Expr
+from sympy.core.function import Lambda
+from sympy.core.logic import fuzzy_not, fuzzy_or, fuzzy_and
+from sympy.core.mod import Mod
+from sympy.core.numbers import oo, igcd, Rational
+from sympy.core.relational import Eq, is_eq
+from sympy.core.kind import NumberKind
+from sympy.core.singleton import Singleton, S
+from sympy.core.symbol import Dummy, symbols, Symbol
+from sympy.core.sympify import _sympify, sympify, _sympy_converter
+from sympy.functions.elementary.integers import ceiling, floor
+from sympy.functions.elementary.trigonometric import sin, cos
+from sympy.logic.boolalg import And, Or
+from .sets import Set, Interval, Union, FiniteSet, ProductSet, SetKind
+from sympy.utilities.misc import filldedent
+
+
+class Rationals(Set, metaclass=Singleton):
+    """
+    Represents the rational numbers. This set is also available as
+    the singleton ``S.Rationals``.
+
+    Examples
+    ========
+
+    >>> from sympy import S
+    >>> S.Half in S.Rationals
+    True
+    >>> iterable = iter(S.Rationals)
+    >>> [next(iterable) for i in range(12)]
+    [0, 1, -1, 1/2, 2, -1/2, -2, 1/3, 3, -1/3, -3, 2/3]
+    """
+
+    is_iterable = True
+    _inf = S.NegativeInfinity
+    _sup = S.Infinity
+    is_empty = False
+    is_finite_set = False
+
+    def _contains(self, other):
+        if not isinstance(other, Expr):
+            return False
+        return other.is_rational
+
+    def __iter__(self):
+        yield S.Zero
+        yield S.One
+        yield S.NegativeOne
+        d = 2
+        while True:
+            for n in range(d):
+                if igcd(n, d) == 1:
+                    yield Rational(n, d)
+                    yield Rational(d, n)
+                    yield Rational(-n, d)
+                    yield Rational(-d, n)
+            d += 1
+
+    @property
+    def _boundary(self):
+        return S.Reals
+
+    def _kind(self):
+        return SetKind(NumberKind)
+
+
+class Naturals(Set, metaclass=Singleton):
+    """
+    Represents the natural numbers (or counting numbers) which are all
+    positive integers starting from 1. This set is also available as
+    the singleton ``S.Naturals``.
+
+    Examples
+    ========
+
+    >>> from sympy import S, Interval, pprint
+    >>> 5 in S.Naturals
+    True
+    >>> iterable = iter(S.Naturals)
+    >>> next(iterable)
+    1
+    >>> next(iterable)
+    2
+    >>> next(iterable)
+    3
+    >>> pprint(S.Naturals.intersect(Interval(0, 10)))
+    {1, 2, ..., 10}
+
+    See Also
+    ========
+
+    Naturals0 : non-negative integers (i.e. includes 0, too)
+    Integers : also includes negative integers
+    """
+
+    is_iterable = True
+    _inf = S.One
+    _sup = S.Infinity
+    is_empty = False
+    is_finite_set = False
+
+    def _contains(self, other):
+        if not isinstance(other, Expr):
+            return False
+        elif other.is_positive and other.is_integer:
+            return True
+        elif other.is_integer is False or other.is_positive is False:
+            return False
+
+    def _eval_is_subset(self, other):
+        return Range(1, oo).is_subset(other)
+
+    def _eval_is_superset(self, other):
+        return Range(1, oo).is_superset(other)
+
+    def __iter__(self):
+        i = self._inf
+        while True:
+            yield i
+            i = i + 1
+
+    @property
+    def _boundary(self):
+        return self
+
+    def as_relational(self, x):
+        return And(Eq(floor(x), x), x >= self.inf, x < oo)
+
+    def _kind(self):
+        return SetKind(NumberKind)
+
+
+class Naturals0(Naturals):
+    """Represents the whole numbers which are all the non-negative integers,
+    inclusive of zero.
+
+    See Also
+    ========
+
+    Naturals : positive integers; does not include 0
+    Integers : also includes the negative integers
+    """
+    _inf = S.Zero
+
+    def _contains(self, other):
+        if not isinstance(other, Expr):
+            return S.false
+        elif other.is_integer and other.is_nonnegative:
+            return S.true
+        elif other.is_integer is False or other.is_nonnegative is False:
+            return S.false
+
+    def _eval_is_subset(self, other):
+        return Range(oo).is_subset(other)
+
+    def _eval_is_superset(self, other):
+        return Range(oo).is_superset(other)
+
+
+class Integers(Set, metaclass=Singleton):
+    """
+    Represents all integers: positive, negative and zero. This set is also
+    available as the singleton ``S.Integers``.
+
+    Examples
+    ========
+
+    >>> from sympy import S, Interval, pprint
+    >>> 5 in S.Naturals
+    True
+    >>> iterable = iter(S.Integers)
+    >>> next(iterable)
+    0
+    >>> next(iterable)
+    1
+    >>> next(iterable)
+    -1
+    >>> next(iterable)
+    2
+
+    >>> pprint(S.Integers.intersect(Interval(-4, 4)))
+    {-4, -3, ..., 4}
+
+    See Also
+    ========
+
+    Naturals0 : non-negative integers
+    Integers : positive and negative integers and zero
+    """
+
+    is_iterable = True
+    is_empty = False
+    is_finite_set = False
+
+    def _contains(self, other):
+        if not isinstance(other, Expr):
+            return S.false
+        return other.is_integer
+
+    def __iter__(self):
+        yield S.Zero
+        i = S.One
+        while True:
+            yield i
+            yield -i
+            i = i + 1
+
+    @property
+    def _inf(self):
+        return S.NegativeInfinity
+
+    @property
+    def _sup(self):
+        return S.Infinity
+
+    @property
+    def _boundary(self):
+        return self
+
+    def _kind(self):
+        return SetKind(NumberKind)
+
+    def as_relational(self, x):
+        return And(Eq(floor(x), x), -oo < x, x < oo)
+
+    def _eval_is_subset(self, other):
+        return Range(-oo, oo).is_subset(other)
+
+    def _eval_is_superset(self, other):
+        return Range(-oo, oo).is_superset(other)
+
+
+class Reals(Interval, metaclass=Singleton):
+    """
+    Represents all real numbers
+    from negative infinity to positive infinity,
+    including all integer, rational and irrational numbers.
+    This set is also available as the singleton ``S.Reals``.
+
+
+    Examples
+    ========
+
+    >>> from sympy import S, Rational, pi, I
+    >>> 5 in S.Reals
+    True
+    >>> Rational(-1, 2) in S.Reals
+    True
+    >>> pi in S.Reals
+    True
+    >>> 3*I in S.Reals
+    False
+    >>> S.Reals.contains(pi)
+    True
+
+
+    See Also
+    ========
+
+    ComplexRegion
+    """
+    @property
+    def start(self):
+        return S.NegativeInfinity
+
+    @property
+    def end(self):
+        return S.Infinity
+
+    @property
+    def left_open(self):
+        return True
+
+    @property
+    def right_open(self):
+        return True
+
+    def __eq__(self, other):
+        return other == Interval(S.NegativeInfinity, S.Infinity)
+
+    def __hash__(self):
+        return hash(Interval(S.NegativeInfinity, S.Infinity))
+
+
+class ImageSet(Set):
+    """
+    Image of a set under a mathematical function. The transformation
+    must be given as a Lambda function which has as many arguments
+    as the elements of the set upon which it operates, e.g. 1 argument
+    when acting on the set of integers or 2 arguments when acting on
+    a complex region.
+
+    This function is not normally called directly, but is called
+    from ``imageset``.
+
+
+    Examples
+    ========
+
+    >>> from sympy import Symbol, S, pi, Dummy, Lambda
+    >>> from sympy import FiniteSet, ImageSet, Interval
+
+    >>> x = Symbol('x')
+    >>> N = S.Naturals
+    >>> squares = ImageSet(Lambda(x, x**2), N) # {x**2 for x in N}
+    >>> 4 in squares
+    True
+    >>> 5 in squares
+    False
+
+    >>> FiniteSet(0, 1, 2, 3, 4, 5, 6, 7, 9, 10).intersect(squares)
+    {1, 4, 9}
+
+    >>> square_iterable = iter(squares)
+    >>> for i in range(4):
+    ...     next(square_iterable)
+    1
+    4
+    9
+    16
+
+    If you want to get value for `x` = 2, 1/2 etc. (Please check whether the
+    `x` value is in ``base_set`` or not before passing it as args)
+
+    >>> squares.lamda(2)
+    4
+    >>> squares.lamda(S(1)/2)
+    1/4
+
+    >>> n = Dummy('n')
+    >>> solutions = ImageSet(Lambda(n, n*pi), S.Integers) # solutions of sin(x) = 0
+    >>> dom = Interval(-1, 1)
+    >>> dom.intersect(solutions)
+    {0}
+
+    See Also
+    ========
+
+    sympy.sets.sets.imageset
+    """
+    def __new__(cls, flambda, *sets):
+        if not isinstance(flambda, Lambda):
+            raise ValueError('First argument must be a Lambda')
+
+        signature = flambda.signature
+
+        if len(signature) != len(sets):
+            raise ValueError('Incompatible signature')
+
+        sets = [_sympify(s) for s in sets]
+
+        if not all(isinstance(s, Set) for s in sets):
+            raise TypeError("Set arguments to ImageSet should of type Set")
+
+        if not all(cls._check_sig(sg, st) for sg, st in zip(signature, sets)):
+            raise ValueError("Signature %s does not match sets %s" % (signature, sets))
+
+        if flambda is S.IdentityFunction and len(sets) == 1:
+            return sets[0]
+
+        if not set(flambda.variables) & flambda.expr.free_symbols:
+            is_empty = fuzzy_or(s.is_empty for s in sets)
+            if is_empty == True:
+                return S.EmptySet
+            elif is_empty == False:
+                return FiniteSet(flambda.expr)
+
+        return Basic.__new__(cls, flambda, *sets)
+
+    lamda = property(lambda self: self.args[0])
+    base_sets = property(lambda self: self.args[1:])
+
+    @property
+    def base_set(self):
+        # XXX: Maybe deprecate this? It is poorly defined in handling
+        # the multivariate case...
+        sets = self.base_sets
+        if len(sets) == 1:
+            return sets[0]
+        else:
+            return ProductSet(*sets).flatten()
+
+    @property
+    def base_pset(self):
+        return ProductSet(*self.base_sets)
+
+    @classmethod
+    def _check_sig(cls, sig_i, set_i):
+        if sig_i.is_symbol:
+            return True
+        elif isinstance(set_i, ProductSet):
+            sets = set_i.sets
+            if len(sig_i) != len(sets):
+                return False
+            # Recurse through the signature for nested tuples:
+            return all(cls._check_sig(ts, ps) for ts, ps in zip(sig_i, sets))
+        else:
+            # XXX: Need a better way of checking whether a set is a set of
+            # Tuples or not. For example a FiniteSet can contain Tuples
+            # but so can an ImageSet or a ConditionSet. Others like
+            # Integers, Reals etc can not contain Tuples. We could just
+            # list the possibilities here... Current code for e.g.
+            # _contains probably only works for ProductSet.
+            return True # Give the benefit of the doubt
+
+    def __iter__(self):
+        already_seen = set()
+        for i in self.base_pset:
+            val = self.lamda(*i)
+            if val in already_seen:
+                continue
+            else:
+                already_seen.add(val)
+                yield val
+
+    def _is_multivariate(self):
+        return len(self.lamda.variables) > 1
+
+    def _contains(self, other):
+        from sympy.solvers.solveset import _solveset_multi
+
+        def get_symsetmap(signature, base_sets):
+            '''Attempt to get a map of symbols to base_sets'''
+            queue = list(zip(signature, base_sets))
+            symsetmap = {}
+            for sig, base_set in queue:
+                if sig.is_symbol:
+                    symsetmap[sig] = base_set
+                elif base_set.is_ProductSet:
+                    sets = base_set.sets
+                    if len(sig) != len(sets):
+                        raise ValueError("Incompatible signature")
+                    # Recurse
+                    queue.extend(zip(sig, sets))
+                else:
+                    # If we get here then we have something like sig = (x, y) and
+                    # base_set = {(1, 2), (3, 4)}. For now we give up.
+                    return None
+
+            return symsetmap
+
+        def get_equations(expr, candidate):
+            '''Find the equations relating symbols in expr and candidate.'''
+            queue = [(expr, candidate)]
+            for e, c in queue:
+                if not isinstance(e, Tuple):
+                    yield Eq(e, c)
+                elif not isinstance(c, Tuple) or len(e) != len(c):
+                    yield False
+                    return
+                else:
+                    queue.extend(zip(e, c))
+
+        # Get the basic objects together:
+        other = _sympify(other)
+        expr = self.lamda.expr
+        sig = self.lamda.signature
+        variables = self.lamda.variables
+        base_sets = self.base_sets
+
+        # Use dummy symbols for ImageSet parameters so they don't match
+        # anything in other
+        rep = {v: Dummy(v.name) for v in variables}
+        variables = [v.subs(rep) for v in variables]
+        sig = sig.subs(rep)
+        expr = expr.subs(rep)
+
+        # Map the parts of other to those in the Lambda expr
+        equations = []
+        for eq in get_equations(expr, other):
+            # Unsatisfiable equation?
+            if eq is False:
+                return False
+            equations.append(eq)
+
+        # Map the symbols in the signature to the corresponding domains
+        symsetmap = get_symsetmap(sig, base_sets)
+        if symsetmap is None:
+            # Can't factor the base sets to a ProductSet
+            return None
+
+        # Which of the variables in the Lambda signature need to be solved for?
+        symss = (eq.free_symbols for eq in equations)
+        variables = set(variables) & reduce(set.union, symss, set())
+
+        # Use internal multivariate solveset
+        variables = tuple(variables)
+        base_sets = [symsetmap[v] for v in variables]
+        solnset = _solveset_multi(equations, variables, base_sets)
+        if solnset is None:
+            return None
+        return fuzzy_not(solnset.is_empty)
+
+    @property
+    def is_iterable(self):
+        return all(s.is_iterable for s in self.base_sets)
+
+    def doit(self, **hints):
+        from sympy.sets.setexpr import SetExpr
+        f = self.lamda
+        sig = f.signature
+        if len(sig) == 1 and sig[0].is_symbol and isinstance(f.expr, Expr):
+            base_set = self.base_sets[0]
+            return SetExpr(base_set)._eval_func(f).set
+        if all(s.is_FiniteSet for s in self.base_sets):
+            return FiniteSet(*(f(*a) for a in product(*self.base_sets)))
+        return self
+
+    def _kind(self):
+        return SetKind(self.lamda.expr.kind)
+
+
+class Range(Set):
+    """
+    Represents a range of integers. Can be called as ``Range(stop)``,
+    ``Range(start, stop)``, or ``Range(start, stop, step)``; when ``step`` is
+    not given it defaults to 1.
+
+    ``Range(stop)`` is the same as ``Range(0, stop, 1)`` and the stop value
+    (just as for Python ranges) is not included in the Range values.
+
+        >>> from sympy import Range
+        >>> list(Range(3))
+        [0, 1, 2]
+
+    The step can also be negative:
+
+        >>> list(Range(10, 0, -2))
+        [10, 8, 6, 4, 2]
+
+    The stop value is made canonical so equivalent ranges always
+    have the same args:
+
+        >>> Range(0, 10, 3)
+        Range(0, 12, 3)
+
+    Infinite ranges are allowed. ``oo`` and ``-oo`` are never included in the
+    set (``Range`` is always a subset of ``Integers``). If the starting point
+    is infinite, then the final value is ``stop - step``. To iterate such a
+    range, it needs to be reversed:
+
+        >>> from sympy import oo
+        >>> r = Range(-oo, 1)
+        >>> r[-1]
+        0
+        >>> next(iter(r))
+        Traceback (most recent call last):
+        ...
+        TypeError: Cannot iterate over Range with infinite start
+        >>> next(iter(r.reversed))
+        0
+
+    Although ``Range`` is a :class:`Set` (and supports the normal set
+    operations) it maintains the order of the elements and can
+    be used in contexts where ``range`` would be used.
+
+        >>> from sympy import Interval
+        >>> Range(0, 10, 2).intersect(Interval(3, 7))
+        Range(4, 8, 2)
+        >>> list(_)
+        [4, 6]
+
+    Although slicing of a Range will always return a Range -- possibly
+    empty -- an empty set will be returned from any intersection that
+    is empty:
+
+        >>> Range(3)[:0]
+        Range(0, 0, 1)
+        >>> Range(3).intersect(Interval(4, oo))
+        EmptySet
+        >>> Range(3).intersect(Range(4, oo))
+        EmptySet
+
+    Range will accept symbolic arguments but has very limited support
+    for doing anything other than displaying the Range:
+
+        >>> from sympy import Symbol, pprint
+        >>> from sympy.abc import i, j, k
+        >>> Range(i, j, k).start
+        i
+        >>> Range(i, j, k).inf
+        Traceback (most recent call last):
+        ...
+        ValueError: invalid method for symbolic range
+
+    Better success will be had when using integer symbols:
+
+        >>> n = Symbol('n', integer=True)
+        >>> r = Range(n, n + 20, 3)
+        >>> r.inf
+        n
+        >>> pprint(r)
+        {n, n + 3, ..., n + 18}
+    """
+
+    def __new__(cls, *args):
+        if len(args) == 1:
+            if isinstance(args[0], range):
+                raise TypeError(
+                    'use sympify(%s) to convert range to Range' % args[0])
+
+        # expand range
+        slc = slice(*args)
+
+        if slc.step == 0:
+            raise ValueError("step cannot be 0")
+
+        start, stop, step = slc.start or 0, slc.stop, slc.step or 1
+        try:
+            ok = []
+            for w in (start, stop, step):
+                w = sympify(w)
+                if w in [S.NegativeInfinity, S.Infinity] or (
+                        w.has(Symbol) and w.is_integer != False):
+                    ok.append(w)
+                elif not w.is_Integer:
+                    if w.is_infinite:
+                        raise ValueError('infinite symbols not allowed')
+                    raise ValueError
+                else:
+                    ok.append(w)
+        except ValueError:
+            raise ValueError(filldedent('''
+    Finite arguments to Range must be integers; `imageset` can define
+    other cases, e.g. use `imageset(i, i/10, Range(3))` to give
+    [0, 1/10, 1/5].'''))
+        start, stop, step = ok
+
+        null = False
+        if any(i.has(Symbol) for i in (start, stop, step)):
+            dif = stop - start
+            n = dif/step
+            if n.is_Rational:
+                if dif == 0:
+                    null = True
+                else:  # (x, x + 5, 2) or (x, 3*x, x)
+                    n = floor(n)
+                    end = start + n*step
+                    if dif.is_Rational:  # (x, x + 5, 2)
+                        if (end - stop).is_negative:
+                            end += step
+                    else:  # (x, 3*x, x)
+                        if (end/stop - 1).is_negative:
+                            end += step
+            elif n.is_extended_negative:
+                null = True
+            else:
+                end = stop  # other methods like sup and reversed must fail
+        elif start.is_infinite:
+            span = step*(stop - start)
+            if span is S.NaN or span <= 0:
+                null = True
+            elif step.is_Integer and stop.is_infinite and abs(step) != 1:
+                raise ValueError(filldedent('''
+                    Step size must be %s in this case.''' % (1 if step > 0 else -1)))
+            else:
+                end = stop
+        else:
+            oostep = step.is_infinite
+            if oostep:
+                step = S.One if step > 0 else S.NegativeOne
+            n = ceiling((stop - start)/step)
+            if n <= 0:
+                null = True
+            elif oostep:
+                step = S.One  # make it canonical
+                end = start + step
+            else:
+                end = start + n*step
+        if null:
+            start = end = S.Zero
+            step = S.One
+        return Basic.__new__(cls, start, end, step)
+
+    start = property(lambda self: self.args[0])
+    stop = property(lambda self: self.args[1])
+    step = property(lambda self: self.args[2])
+
+    @property
+    def reversed(self):
+        """Return an equivalent Range in the opposite order.
+
+        Examples
+        ========
+
+        >>> from sympy import Range
+        >>> Range(10).reversed
+        Range(9, -1, -1)
+        """
+        if self.has(Symbol):
+            n = (self.stop - self.start)/self.step
+            if not n.is_extended_positive or not all(
+                    i.is_integer or i.is_infinite for i in self.args):
+                raise ValueError('invalid method for symbolic range')
+        if self.start == self.stop:
+            return self
+        return self.func(
+            self.stop - self.step, self.start - self.step, -self.step)
+
+    def _kind(self):
+        return SetKind(NumberKind)
+
+    def _contains(self, other):
+        if self.start == self.stop:
+            return S.false
+        if other.is_infinite:
+            return S.false
+        if not other.is_integer:
+            return other.is_integer
+        if self.has(Symbol):
+            n = (self.stop - self.start)/self.step
+            if not n.is_extended_positive or not all(
+                    i.is_integer or i.is_infinite for i in self.args):
+                return
+        else:
+            n = self.size
+        if self.start.is_finite:
+            ref = self.start
+        elif self.stop.is_finite:
+            ref = self.stop
+        else:  # both infinite; step is +/- 1 (enforced by __new__)
+            return S.true
+        if n == 1:
+            return Eq(other, self[0])
+        res = (ref - other) % self.step
+        if res == S.Zero:
+            if self.has(Symbol):
+                d = Dummy('i')
+                return self.as_relational(d).subs(d, other)
+            return And(other >= self.inf, other <= self.sup)
+        elif res.is_Integer:  # off sequence
+            return S.false
+        else:  # symbolic/unsimplified residue modulo step
+            return None
+
+    def __iter__(self):
+        n = self.size  # validate
+        if not (n.has(S.Infinity) or n.has(S.NegativeInfinity) or n.is_Integer):
+            raise TypeError("Cannot iterate over symbolic Range")
+        if self.start in [S.NegativeInfinity, S.Infinity]:
+            raise TypeError("Cannot iterate over Range with infinite start")
+        elif self.start != self.stop:
+            i = self.start
+            if n.is_infinite:
+                while True:
+                    yield i
+                    i += self.step
+            else:
+                for _ in range(n):
+                    yield i
+                    i += self.step
+
+    @property
+    def is_iterable(self):
+        # Check that size can be determined, used by __iter__
+        dif = self.stop - self.start
+        n = dif/self.step
+        if not (n.has(S.Infinity) or n.has(S.NegativeInfinity) or n.is_Integer):
+            return False
+        if self.start in [S.NegativeInfinity, S.Infinity]:
+            return False
+        if not (n.is_extended_nonnegative and all(i.is_integer for i in self.args)):
+            return False
+        return True
+
+    def __len__(self):
+        rv = self.size
+        if rv is S.Infinity:
+            raise ValueError('Use .size to get the length of an infinite Range')
+        return int(rv)
+
+    @property
+    def size(self):
+        if self.start == self.stop:
+            return S.Zero
+        dif = self.stop - self.start
+        n = dif/self.step
+        if n.is_infinite:
+            return S.Infinity
+        if  n.is_extended_nonnegative and all(i.is_integer for i in self.args):
+            return abs(floor(n))
+        raise ValueError('Invalid method for symbolic Range')
+
+    @property
+    def is_finite_set(self):
+        if self.start.is_integer and self.stop.is_integer:
+            return True
+        return self.size.is_finite
+
+    @property
+    def is_empty(self):
+        try:
+            return self.size.is_zero
+        except ValueError:
+            return None
+
+    def __bool__(self):
+        # this only distinguishes between definite null range
+        # and non-null/unknown null; getting True doesn't mean
+        # that it actually is not null
+        b = is_eq(self.start, self.stop)
+        if b is None:
+            raise ValueError('cannot tell if Range is null or not')
+        return not bool(b)
+
+    def __getitem__(self, i):
+        ooslice = "cannot slice from the end with an infinite value"
+        zerostep = "slice step cannot be zero"
+        infinite = "slicing not possible on range with infinite start"
+        # if we had to take every other element in the following
+        # oo, ..., 6, 4, 2, 0
+        # we might get oo, ..., 4, 0 or oo, ..., 6, 2
+        ambiguous = "cannot unambiguously re-stride from the end " + \
+            "with an infinite value"
+        if isinstance(i, slice):
+            if self.size.is_finite:  # validates, too
+                if self.start == self.stop:
+                    return Range(0)
+                start, stop, step = i.indices(self.size)
+                n = ceiling((stop - start)/step)
+                if n <= 0:
+                    return Range(0)
+                canonical_stop = start + n*step
+                end = canonical_stop - step
+                ss = step*self.step
+                return Range(self[start], self[end] + ss, ss)
+            else:  # infinite Range
+                start = i.start
+                stop = i.stop
+                if i.step == 0:
+                    raise ValueError(zerostep)
+                step = i.step or 1
+                ss = step*self.step
+                #---------------------
+                # handle infinite Range
+                #   i.e. Range(-oo, oo) or Range(oo, -oo, -1)
+                # --------------------
+                if self.start.is_infinite and self.stop.is_infinite:
+                    raise ValueError(infinite)
+                #---------------------
+                # handle infinite on right
+                #   e.g. Range(0, oo) or Range(0, -oo, -1)
+                # --------------------
+                if self.stop.is_infinite:
+                    # start and stop are not interdependent --
+                    # they only depend on step --so we use the
+                    # equivalent reversed values
+                    return self.reversed[
+                        stop if stop is None else -stop + 1:
+                        start if start is None else -start:
+                        step].reversed
+                #---------------------
+                # handle infinite on the left
+                #   e.g. Range(oo, 0, -1) or Range(-oo, 0)
+                # --------------------
+                # consider combinations of
+                # start/stop {== None, < 0, == 0, > 0} and
+                # step {< 0, > 0}
+                if start is None:
+                    if stop is None:
+                        if step < 0:
+                            return Range(self[-1], self.start, ss)
+                        elif step > 1:
+                            raise ValueError(ambiguous)
+                        else:  # == 1
+                            return self
+                    elif stop < 0:
+                        if step < 0:
+                            return Range(self[-1], self[stop], ss)
+                        else:  # > 0
+                            return Range(self.start, self[stop], ss)
+                    elif stop == 0:
+                        if step > 0:
+                            return Range(0)
+                        else:  # < 0
+                            raise ValueError(ooslice)
+                    elif stop == 1:
+                        if step > 0:
+                            raise ValueError(ooslice)  # infinite singleton
+                        else:  # < 0
+                            raise ValueError(ooslice)
+                    else:  # > 1
+                        raise ValueError(ooslice)
+                elif start < 0:
+                    if stop is None:
+                        if step < 0:
+                            return Range(self[start], self.start, ss)
+                        else:  # > 0
+                            return Range(self[start], self.stop, ss)
+                    elif stop < 0:
+                        return Range(self[start], self[stop], ss)
+                    elif stop == 0:
+                        if step < 0:
+                            raise ValueError(ooslice)
+                        else:  # > 0
+                            return Range(0)
+                    elif stop > 0:
+                        raise ValueError(ooslice)
+                elif start == 0:
+                    if stop is None:
+                        if step < 0:
+                            raise ValueError(ooslice)  # infinite singleton
+                        elif step > 1:
+                            raise ValueError(ambiguous)
+                        else:  # == 1
+                            return self
+                    elif stop < 0:
+                        if step > 1:
+                            raise ValueError(ambiguous)
+                        elif step == 1:
+                            return Range(self.start, self[stop], ss)
+                        else:  # < 0
+                            return Range(0)
+                    else:  # >= 0
+                        raise ValueError(ooslice)
+                elif start > 0:
+                    raise ValueError(ooslice)
+        else:
+            if self.start == self.stop:
+                raise IndexError('Range index out of range')
+            if not (all(i.is_integer or i.is_infinite
+                    for i in self.args) and ((self.stop - self.start)/
+                    self.step).is_extended_positive):
+                raise ValueError('Invalid method for symbolic Range')
+            if i == 0:
+                if self.start.is_infinite:
+                    raise ValueError(ooslice)
+                return self.start
+            if i == -1:
+                if self.stop.is_infinite:
+                    raise ValueError(ooslice)
+                return self.stop - self.step
+            n = self.size  # must be known for any other index
+            rv = (self.stop if i < 0 else self.start) + i*self.step
+            if rv.is_infinite:
+                raise ValueError(ooslice)
+            val = (rv - self.start)/self.step
+            rel = fuzzy_or([val.is_infinite,
+                            fuzzy_and([val.is_nonnegative, (n-val).is_nonnegative])])
+            if rel:
+                return rv
+            if rel is None:
+                raise ValueError('Invalid method for symbolic Range')
+            raise IndexError("Range index out of range")
+
+    @property
+    def _inf(self):
+        if not self:
+            return S.EmptySet.inf
+        if self.has(Symbol):
+            if all(i.is_integer or i.is_infinite for i in self.args):
+                dif = self.stop - self.start
+                if self.step.is_positive and dif.is_positive:
+                    return self.start
+                elif self.step.is_negative and dif.is_negative:
+                    return self.stop - self.step
+            raise ValueError('invalid method for symbolic range')
+        if self.step > 0:
+            return self.start
+        else:
+            return self.stop - self.step
+
+    @property
+    def _sup(self):
+        if not self:
+            return S.EmptySet.sup
+        if self.has(Symbol):
+            if all(i.is_integer or i.is_infinite for i in self.args):
+                dif = self.stop - self.start
+                if self.step.is_positive and dif.is_positive:
+                    return self.stop - self.step
+                elif self.step.is_negative and dif.is_negative:
+                    return self.start
+            raise ValueError('invalid method for symbolic range')
+        if self.step > 0:
+            return self.stop - self.step
+        else:
+            return self.start
+
+    @property
+    def _boundary(self):
+        return self
+
+    def as_relational(self, x):
+        """Rewrite a Range in terms of equalities and logic operators. """
+        if self.start.is_infinite:
+            assert not self.stop.is_infinite  # by instantiation
+            a = self.reversed.start
+        else:
+            a = self.start
+        step = self.step
+        in_seq = Eq(Mod(x - a, step), 0)
+        ints = And(Eq(Mod(a, 1), 0), Eq(Mod(step, 1), 0))
+        n = (self.stop - self.start)/self.step
+        if n == 0:
+            return S.EmptySet.as_relational(x)
+        if n == 1:
+            return And(Eq(x, a), ints)
+        try:
+            a, b = self.inf, self.sup
+        except ValueError:
+            a = None
+        if a is not None:
+            range_cond = And(
+                x > a if a.is_infinite else x >= a,
+                x < b if b.is_infinite else x <= b)
+        else:
+            a, b = self.start, self.stop - self.step
+            range_cond = Or(
+                And(self.step >= 1, x > a if a.is_infinite else x >= a,
+                x < b if b.is_infinite else x <= b),
+                And(self.step <= -1, x < a if a.is_infinite else x <= a,
+                x > b if b.is_infinite else x >= b))
+        return And(in_seq, ints, range_cond)
+
+
+_sympy_converter[range] = lambda r: Range(r.start, r.stop, r.step)
+
+def normalize_theta_set(theta):
+    r"""
+    Normalize a Real Set `theta` in the interval `[0, 2\pi)`. It returns
+    a normalized value of theta in the Set. For Interval, a maximum of
+    one cycle $[0, 2\pi]$, is returned i.e. for theta equal to $[0, 10\pi]$,
+    returned normalized value would be $[0, 2\pi)$. As of now intervals
+    with end points as non-multiples of ``pi`` is not supported.
+
+    Raises
+    ======
+
+    NotImplementedError
+        The algorithms for Normalizing theta Set are not yet
+        implemented.
+    ValueError
+        The input is not valid, i.e. the input is not a real set.
+    RuntimeError
+        It is a bug, please report to the github issue tracker.
+
+    Examples
+    ========
+
+    >>> from sympy.sets.fancysets import normalize_theta_set
+    >>> from sympy import Interval, FiniteSet, pi
+    >>> normalize_theta_set(Interval(9*pi/2, 5*pi))
+    Interval(pi/2, pi)
+    >>> normalize_theta_set(Interval(-3*pi/2, pi/2))
+    Interval.Ropen(0, 2*pi)
+    >>> normalize_theta_set(Interval(-pi/2, pi/2))
+    Union(Interval(0, pi/2), Interval.Ropen(3*pi/2, 2*pi))
+    >>> normalize_theta_set(Interval(-4*pi, 3*pi))
+    Interval.Ropen(0, 2*pi)
+    >>> normalize_theta_set(Interval(-3*pi/2, -pi/2))
+    Interval(pi/2, 3*pi/2)
+    >>> normalize_theta_set(FiniteSet(0, pi, 3*pi))
+    {0, pi}
+
+    """
+    from sympy.functions.elementary.trigonometric import _pi_coeff
+
+    if theta.is_Interval:
+        interval_len = theta.measure
+        # one complete circle
+        if interval_len >= 2*S.Pi:
+            if interval_len == 2*S.Pi and theta.left_open and theta.right_open:
+                k = _pi_coeff(theta.start)
+                return Union(Interval(0, k*S.Pi, False, True),
+                        Interval(k*S.Pi, 2*S.Pi, True, True))
+            return Interval(0, 2*S.Pi, False, True)
+
+        k_start, k_end = _pi_coeff(theta.start), _pi_coeff(theta.end)
+
+        if k_start is None or k_end is None:
+            raise NotImplementedError("Normalizing theta without pi as coefficient is "
+                                    "not yet implemented")
+        new_start = k_start*S.Pi
+        new_end = k_end*S.Pi
+
+        if new_start > new_end:
+            return Union(Interval(S.Zero, new_end, False, theta.right_open),
+                         Interval(new_start, 2*S.Pi, theta.left_open, True))
+        else:
+            return Interval(new_start, new_end, theta.left_open, theta.right_open)
+
+    elif theta.is_FiniteSet:
+        new_theta = []
+        for element in theta:
+            k = _pi_coeff(element)
+            if k is None:
+                raise NotImplementedError('Normalizing theta without pi as '
+                                          'coefficient, is not Implemented.')
+            else:
+                new_theta.append(k*S.Pi)
+        return FiniteSet(*new_theta)
+
+    elif theta.is_Union:
+        return Union(*[normalize_theta_set(interval) for interval in theta.args])
+
+    elif theta.is_subset(S.Reals):
+        raise NotImplementedError("Normalizing theta when, it is of type %s is not "
+                                  "implemented" % type(theta))
+    else:
+        raise ValueError(" %s is not a real set" % (theta))
+
+
+class ComplexRegion(Set):
+    r"""
+    Represents the Set of all Complex Numbers. It can represent a
+    region of Complex Plane in both the standard forms Polar and
+    Rectangular coordinates.
+
+    * Polar Form
+      Input is in the form of the ProductSet or Union of ProductSets
+      of the intervals of ``r`` and ``theta``, and use the flag ``polar=True``.
+
+      .. math:: Z = \{z \in \mathbb{C} \mid z = r\times (\cos(\theta) + I\sin(\theta)), r \in [\texttt{r}], \theta \in [\texttt{theta}]\}
+
+    * Rectangular Form
+      Input is in the form of the ProductSet or Union of ProductSets
+      of interval of x and y, the real and imaginary parts of the Complex numbers in a plane.
+      Default input type is in rectangular form.
+
+    .. math:: Z = \{z \in \mathbb{C} \mid z = x + Iy, x \in [\operatorname{re}(z)], y \in [\operatorname{im}(z)]\}
+
+    Examples
+    ========
+
+    >>> from sympy import ComplexRegion, Interval, S, I, Union
+    >>> a = Interval(2, 3)
+    >>> b = Interval(4, 6)
+    >>> c1 = ComplexRegion(a*b)  # Rectangular Form
+    >>> c1
+    CartesianComplexRegion(ProductSet(Interval(2, 3), Interval(4, 6)))
+
+    * c1 represents the rectangular region in complex plane
+      surrounded by the coordinates (2, 4), (3, 4), (3, 6) and
+      (2, 6), of the four vertices.
+
+    >>> c = Interval(1, 8)
+    >>> c2 = ComplexRegion(Union(a*b, b*c))
+    >>> c2
+    CartesianComplexRegion(Union(ProductSet(Interval(2, 3), Interval(4, 6)), ProductSet(Interval(4, 6), Interval(1, 8))))
+
+    * c2 represents the Union of two rectangular regions in complex
+      plane. One of them surrounded by the coordinates of c1 and
+      other surrounded by the coordinates (4, 1), (6, 1), (6, 8) and
+      (4, 8).
+
+    >>> 2.5 + 4.5*I in c1
+    True
+    >>> 2.5 + 6.5*I in c1
+    False
+
+    >>> r = Interval(0, 1)
+    >>> theta = Interval(0, 2*S.Pi)
+    >>> c2 = ComplexRegion(r*theta, polar=True)  # Polar Form
+    >>> c2  # unit Disk
+    PolarComplexRegion(ProductSet(Interval(0, 1), Interval.Ropen(0, 2*pi)))
+
+    * c2 represents the region in complex plane inside the
+      Unit Disk centered at the origin.
+
+    >>> 0.5 + 0.5*I in c2
+    True
+    >>> 1 + 2*I in c2
+    False
+
+    >>> unit_disk = ComplexRegion(Interval(0, 1)*Interval(0, 2*S.Pi), polar=True)
+    >>> upper_half_unit_disk = ComplexRegion(Interval(0, 1)*Interval(0, S.Pi), polar=True)
+    >>> intersection = unit_disk.intersect(upper_half_unit_disk)
+    >>> intersection
+    PolarComplexRegion(ProductSet(Interval(0, 1), Interval(0, pi)))
+    >>> intersection == upper_half_unit_disk
+    True
+
+    See Also
+    ========
+
+    CartesianComplexRegion
+    PolarComplexRegion
+    Complexes
+
+    """
+    is_ComplexRegion = True
+
+    def __new__(cls, sets, polar=False):
+        if polar is False:
+            return CartesianComplexRegion(sets)
+        elif polar is True:
+            return PolarComplexRegion(sets)
+        else:
+            raise ValueError("polar should be either True or False")
+
+    @property
+    def sets(self):
+        """
+        Return raw input sets to the self.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, ComplexRegion, Union
+        >>> a = Interval(2, 3)
+        >>> b = Interval(4, 5)
+        >>> c = Interval(1, 7)
+        >>> C1 = ComplexRegion(a*b)
+        >>> C1.sets
+        ProductSet(Interval(2, 3), Interval(4, 5))
+        >>> C2 = ComplexRegion(Union(a*b, b*c))
+        >>> C2.sets
+        Union(ProductSet(Interval(2, 3), Interval(4, 5)), ProductSet(Interval(4, 5), Interval(1, 7)))
+
+        """
+        return self.args[0]
+
+    @property
+    def psets(self):
+        """
+        Return a tuple of sets (ProductSets) input of the self.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, ComplexRegion, Union
+        >>> a = Interval(2, 3)
+        >>> b = Interval(4, 5)
+        >>> c = Interval(1, 7)
+        >>> C1 = ComplexRegion(a*b)
+        >>> C1.psets
+        (ProductSet(Interval(2, 3), Interval(4, 5)),)
+        >>> C2 = ComplexRegion(Union(a*b, b*c))
+        >>> C2.psets
+        (ProductSet(Interval(2, 3), Interval(4, 5)), ProductSet(Interval(4, 5), Interval(1, 7)))
+
+        """
+        if self.sets.is_ProductSet:
+            psets = ()
+            psets = psets + (self.sets, )
+        else:
+            psets = self.sets.args
+        return psets
+
+    @property
+    def a_interval(self):
+        """
+        Return the union of intervals of `x` when, self is in
+        rectangular form, or the union of intervals of `r` when
+        self is in polar form.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, ComplexRegion, Union
+        >>> a = Interval(2, 3)
+        >>> b = Interval(4, 5)
+        >>> c = Interval(1, 7)
+        >>> C1 = ComplexRegion(a*b)
+        >>> C1.a_interval
+        Interval(2, 3)
+        >>> C2 = ComplexRegion(Union(a*b, b*c))
+        >>> C2.a_interval
+        Union(Interval(2, 3), Interval(4, 5))
+
+        """
+        a_interval = []
+        for element in self.psets:
+            a_interval.append(element.args[0])
+
+        a_interval = Union(*a_interval)
+        return a_interval
+
+    @property
+    def b_interval(self):
+        """
+        Return the union of intervals of `y` when, self is in
+        rectangular form, or the union of intervals of `theta`
+        when self is in polar form.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, ComplexRegion, Union
+        >>> a = Interval(2, 3)
+        >>> b = Interval(4, 5)
+        >>> c = Interval(1, 7)
+        >>> C1 = ComplexRegion(a*b)
+        >>> C1.b_interval
+        Interval(4, 5)
+        >>> C2 = ComplexRegion(Union(a*b, b*c))
+        >>> C2.b_interval
+        Interval(1, 7)
+
+        """
+        b_interval = []
+        for element in self.psets:
+            b_interval.append(element.args[1])
+
+        b_interval = Union(*b_interval)
+        return b_interval
+
+    @property
+    def _measure(self):
+        """
+        The measure of self.sets.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, ComplexRegion, S
+        >>> a, b = Interval(2, 5), Interval(4, 8)
+        >>> c = Interval(0, 2*S.Pi)
+        >>> c1 = ComplexRegion(a*b)
+        >>> c1.measure
+        12
+        >>> c2 = ComplexRegion(a*c, polar=True)
+        >>> c2.measure
+        6*pi
+
+        """
+        return self.sets._measure
+
+    def _kind(self):
+        return self.args[0].kind
+
+    @classmethod
+    def from_real(cls, sets):
+        """
+        Converts given subset of real numbers to a complex region.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, ComplexRegion
+        >>> unit = Interval(0,1)
+        >>> ComplexRegion.from_real(unit)
+        CartesianComplexRegion(ProductSet(Interval(0, 1), {0}))
+
+        """
+        if not sets.is_subset(S.Reals):
+            raise ValueError("sets must be a subset of the real line")
+
+        return CartesianComplexRegion(sets * FiniteSet(0))
+
+    def _contains(self, other):
+        from sympy.functions import arg, Abs
+        other = sympify(other)
+        isTuple = isinstance(other, Tuple)
+        if isTuple and len(other) != 2:
+            raise ValueError('expecting Tuple of length 2')
+
+        # If the other is not an Expression, and neither a Tuple
+        if not isinstance(other, (Expr, Tuple)):
+            return S.false
+        # self in rectangular form
+        if not self.polar:
+            re, im = other if isTuple else other.as_real_imag()
+            return fuzzy_or(fuzzy_and([
+                pset.args[0]._contains(re),
+                pset.args[1]._contains(im)])
+                for pset in self.psets)
+
+        # self in polar form
+        elif self.polar:
+            if other.is_zero:
+                # ignore undefined complex argument
+                return fuzzy_or(pset.args[0]._contains(S.Zero)
+                    for pset in self.psets)
+            if isTuple:
+                r, theta = other
+            else:
+                r, theta = Abs(other), arg(other)
+            if theta.is_real and theta.is_number:
+                # angles in psets are normalized to [0, 2pi)
+                theta %= 2*S.Pi
+                return fuzzy_or(fuzzy_and([
+                    pset.args[0]._contains(r),
+                    pset.args[1]._contains(theta)])
+                    for pset in self.psets)
+
+
+class CartesianComplexRegion(ComplexRegion):
+    r"""
+    Set representing a square region of the complex plane.
+
+    .. math:: Z = \{z \in \mathbb{C} \mid z = x + Iy, x \in [\operatorname{re}(z)], y \in [\operatorname{im}(z)]\}
+
+    Examples
+    ========
+
+    >>> from sympy import ComplexRegion, I, Interval
+    >>> region = ComplexRegion(Interval(1, 3) * Interval(4, 6))
+    >>> 2 + 5*I in region
+    True
+    >>> 5*I in region
+    False
+
+    See also
+    ========
+
+    ComplexRegion
+    PolarComplexRegion
+    Complexes
+    """
+
+    polar = False
+    variables = symbols('x, y', cls=Dummy)
+
+    def __new__(cls, sets):
+
+        if sets == S.Reals*S.Reals:
+            return S.Complexes
+
+        if all(_a.is_FiniteSet for _a in sets.args) and (len(sets.args) == 2):
+
+            # ** ProductSet of FiniteSets in the Complex Plane. **
+            # For Cases like ComplexRegion({2, 4}*{3}), It
+            # would return {2 + 3*I, 4 + 3*I}
+
+            # FIXME: This should probably be handled with something like:
+            # return ImageSet(Lambda((x, y), x+I*y), sets).rewrite(FiniteSet)
+            complex_num = []
+            for x in sets.args[0]:
+                for y in sets.args[1]:
+                    complex_num.append(x + S.ImaginaryUnit*y)
+            return FiniteSet(*complex_num)
+        else:
+            return Set.__new__(cls, sets)
+
+    @property
+    def expr(self):
+        x, y = self.variables
+        return x + S.ImaginaryUnit*y
+
+
+class PolarComplexRegion(ComplexRegion):
+    r"""
+    Set representing a polar region of the complex plane.
+
+    .. math:: Z = \{z \in \mathbb{C} \mid z = r\times (\cos(\theta) + I\sin(\theta)), r \in [\texttt{r}], \theta \in [\texttt{theta}]\}
+
+    Examples
+    ========
+
+    >>> from sympy import ComplexRegion, Interval, oo, pi, I
+    >>> rset = Interval(0, oo)
+    >>> thetaset = Interval(0, pi)
+    >>> upper_half_plane = ComplexRegion(rset * thetaset, polar=True)
+    >>> 1 + I in upper_half_plane
+    True
+    >>> 1 - I in upper_half_plane
+    False
+
+    See also
+    ========
+
+    ComplexRegion
+    CartesianComplexRegion
+    Complexes
+
+    """
+
+    polar = True
+    variables = symbols('r, theta', cls=Dummy)
+
+    def __new__(cls, sets):
+
+        new_sets = []
+        # sets is Union of ProductSets
+        if not sets.is_ProductSet:
+            for k in sets.args:
+                new_sets.append(k)
+        # sets is ProductSets
+        else:
+            new_sets.append(sets)
+        # Normalize input theta
+        for k, v in enumerate(new_sets):
+            new_sets[k] = ProductSet(v.args[0],
+                                     normalize_theta_set(v.args[1]))
+        sets = Union(*new_sets)
+        return Set.__new__(cls, sets)
+
+    @property
+    def expr(self):
+        r, theta = self.variables
+        return r*(cos(theta) + S.ImaginaryUnit*sin(theta))
+
+
+class Complexes(CartesianComplexRegion, metaclass=Singleton):
+    """
+    The :class:`Set` of all complex numbers
+
+    Examples
+    ========
+
+    >>> from sympy import S, I
+    >>> S.Complexes
+    Complexes
+    >>> 1 + I in S.Complexes
+    True
+
+    See also
+    ========
+
+    Reals
+    ComplexRegion
+
+    """
+
+    is_empty = False
+    is_finite_set = False
+
+    # Override property from superclass since Complexes has no args
+    @property
+    def sets(self):
+        return ProductSet(S.Reals, S.Reals)
+
+    def __new__(cls):
+        return Set.__new__(cls)

venv/lib/python3.10/site-packages/sympy/sets/ordinals.py

@@ -0,0 +1,282 @@
+from sympy.core import Basic, Integer
+import operator
+
+
+class OmegaPower(Basic):
+    """
+    Represents ordinal exponential and multiplication terms one of the
+    building blocks of the :class:`Ordinal` class.
+    In ``OmegaPower(a, b)``, ``a`` represents exponent and ``b`` represents multiplicity.
+    """
+    def __new__(cls, a, b):
+        if isinstance(b, int):
+            b = Integer(b)
+        if not isinstance(b, Integer) or b <= 0:
+            raise TypeError("multiplicity must be a positive integer")
+
+        if not isinstance(a, Ordinal):
+            a = Ordinal.convert(a)
+
+        return Basic.__new__(cls, a, b)
+
+    @property
+    def exp(self):
+        return self.args[0]
+
+    @property
+    def mult(self):
+        return self.args[1]
+
+    def _compare_term(self, other, op):
+        if self.exp == other.exp:
+            return op(self.mult, other.mult)
+        else:
+            return op(self.exp, other.exp)
+
+    def __eq__(self, other):
+        if not isinstance(other, OmegaPower):
+            try:
+                other = OmegaPower(0, other)
+            except TypeError:
+                return NotImplemented
+        return self.args == other.args
+
+    def __hash__(self):
+        return Basic.__hash__(self)
+
+    def __lt__(self, other):
+        if not isinstance(other, OmegaPower):
+            try:
+                other = OmegaPower(0, other)
+            except TypeError:
+                return NotImplemented
+        return self._compare_term(other, operator.lt)
+
+
+class Ordinal(Basic):
+    """
+    Represents ordinals in Cantor normal form.
+
+    Internally, this class is just a list of instances of OmegaPower.
+
+    Examples
+    ========
+    >>> from sympy import Ordinal, OmegaPower
+    >>> from sympy.sets.ordinals import omega
+    >>> w = omega
+    >>> w.is_limit_ordinal
+    True
+    >>> Ordinal(OmegaPower(w + 1, 1), OmegaPower(3, 2))
+    w**(w + 1) + w**3*2
+    >>> 3 + w
+    w
+    >>> (w + 1) * w
+    w**2
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Ordinal_arithmetic
+    """
+    def __new__(cls, *terms):
+        obj = super().__new__(cls, *terms)
+        powers = [i.exp for i in obj.args]
+        if not all(powers[i] >= powers[i+1] for i in range(len(powers) - 1)):
+            raise ValueError("powers must be in decreasing order")
+        return obj
+
+    @property
+    def terms(self):
+        return self.args
+
+    @property
+    def leading_term(self):
+        if self == ord0:
+            raise ValueError("ordinal zero has no leading term")
+        return self.terms[0]
+
+    @property
+    def trailing_term(self):
+        if self == ord0:
+            raise ValueError("ordinal zero has no trailing term")
+        return self.terms[-1]
+
+    @property
+    def is_successor_ordinal(self):
+        try:
+            return self.trailing_term.exp == ord0
+        except ValueError:
+            return False
+
+    @property
+    def is_limit_ordinal(self):
+        try:
+            return not self.trailing_term.exp == ord0
+        except ValueError:
+            return False
+
+    @property
+    def degree(self):
+        return self.leading_term.exp
+
+    @classmethod
+    def convert(cls, integer_value):
+        if integer_value == 0:
+            return ord0
+        return Ordinal(OmegaPower(0, integer_value))
+
+    def __eq__(self, other):
+        if not isinstance(other, Ordinal):
+            try:
+                other = Ordinal.convert(other)
+            except TypeError:
+                return NotImplemented
+        return self.terms == other.terms
+
+    def __hash__(self):
+        return hash(self.args)
+
+    def __lt__(self, other):
+        if not isinstance(other, Ordinal):
+            try:
+                other = Ordinal.convert(other)
+            except TypeError:
+                return NotImplemented
+        for term_self, term_other in zip(self.terms, other.terms):
+            if term_self != term_other:
+                return term_self < term_other
+        return len(self.terms) < len(other.terms)
+
+    def __le__(self, other):
+        return (self == other or self < other)
+
+    def __gt__(self, other):
+        return not self <= other
+
+    def __ge__(self, other):
+        return not self < other
+
+    def __str__(self):
+        net_str = ""
+        plus_count = 0
+        if self == ord0:
+            return 'ord0'
+        for i in self.terms:
+            if plus_count:
+                net_str += " + "
+
+            if i.exp == ord0:
+                net_str += str(i.mult)
+            elif i.exp == 1:
+                net_str += 'w'
+            elif len(i.exp.terms) > 1 or i.exp.is_limit_ordinal:
+                net_str += 'w**(%s)'%i.exp
+            else:
+                net_str += 'w**%s'%i.exp
+
+            if not i.mult == 1 and not i.exp == ord0:
+                net_str += '*%s'%i.mult
+
+            plus_count += 1
+        return(net_str)
+
+    __repr__ = __str__
+
+    def __add__(self, other):
+        if not isinstance(other, Ordinal):
+            try:
+                other = Ordinal.convert(other)
+            except TypeError:
+                return NotImplemented
+        if other == ord0:
+            return self
+        a_terms = list(self.terms)
+        b_terms = list(other.terms)
+        r = len(a_terms) - 1
+        b_exp = other.degree
+        while r >= 0 and a_terms[r].exp < b_exp:
+            r -= 1
+        if r < 0:
+            terms = b_terms
+        elif a_terms[r].exp == b_exp:
+            sum_term = OmegaPower(b_exp, a_terms[r].mult + other.leading_term.mult)
+            terms = a_terms[:r] + [sum_term] + b_terms[1:]
+        else:
+            terms = a_terms[:r+1] + b_terms
+        return Ordinal(*terms)
+
+    def __radd__(self, other):
+        if not isinstance(other, Ordinal):
+            try:
+                other = Ordinal.convert(other)
+            except TypeError:
+                return NotImplemented
+        return other + self
+
+    def __mul__(self, other):
+        if not isinstance(other, Ordinal):
+            try:
+                other = Ordinal.convert(other)
+            except TypeError:
+                return NotImplemented
+        if ord0 in (self, other):
+            return ord0
+        a_exp = self.degree
+        a_mult = self.leading_term.mult
+        summation = []
+        if other.is_limit_ordinal:
+            for arg in other.terms:
+                summation.append(OmegaPower(a_exp + arg.exp, arg.mult))
+
+        else:
+            for arg in other.terms[:-1]:
+                summation.append(OmegaPower(a_exp + arg.exp, arg.mult))
+            b_mult = other.trailing_term.mult
+            summation.append(OmegaPower(a_exp, a_mult*b_mult))
+            summation += list(self.terms[1:])
+        return Ordinal(*summation)
+
+    def __rmul__(self, other):
+        if not isinstance(other, Ordinal):
+            try:
+                other = Ordinal.convert(other)
+            except TypeError:
+                return NotImplemented
+        return other * self
+
+    def __pow__(self, other):
+        if not self == omega:
+            return NotImplemented
+        return Ordinal(OmegaPower(other, 1))
+
+
+class OrdinalZero(Ordinal):
+    """The ordinal zero.
+
+    OrdinalZero can be imported as ``ord0``.
+    """
+    pass
+
+
+class OrdinalOmega(Ordinal):
+    """The ordinal omega which forms the base of all ordinals in cantor normal form.
+
+    OrdinalOmega can be imported as ``omega``.
+
+    Examples
+    ========
+
+    >>> from sympy.sets.ordinals import omega
+    >>> omega + omega
+    w*2
+    """
+    def __new__(cls):
+        return Ordinal.__new__(cls)
+
+    @property
+    def terms(self):
+        return (OmegaPower(1, 1),)
+
+
+ord0 = OrdinalZero()
+omega = OrdinalOmega()

venv/lib/python3.10/site-packages/sympy/sets/powerset.py

@@ -0,0 +1,119 @@
+from sympy.core.decorators import _sympifyit
+from sympy.core.parameters import global_parameters
+from sympy.core.logic import fuzzy_bool
+from sympy.core.singleton import S
+from sympy.core.sympify import _sympify
+
+from .sets import Set, FiniteSet, SetKind
+
+
+class PowerSet(Set):
+    r"""A symbolic object representing a power set.
+
+    Parameters
+    ==========
+
+    arg : Set
+        The set to take power of.
+
+    evaluate : bool
+        The flag to control evaluation.
+
+        If the evaluation is disabled for finite sets, it can take
+        advantage of using subset test as a membership test.
+
+    Notes
+    =====
+
+    Power set `\mathcal{P}(S)` is defined as a set containing all the
+    subsets of `S`.
+
+    If the set `S` is a finite set, its power set would have
+    `2^{\left| S \right|}` elements, where `\left| S \right|` denotes
+    the cardinality of `S`.
+
+    Examples
+    ========
+
+    >>> from sympy import PowerSet, S, FiniteSet
+
+    A power set of a finite set:
+
+    >>> PowerSet(FiniteSet(1, 2, 3))
+    PowerSet({1, 2, 3})
+
+    A power set of an empty set:
+
+    >>> PowerSet(S.EmptySet)
+    PowerSet(EmptySet)
+    >>> PowerSet(PowerSet(S.EmptySet))
+    PowerSet(PowerSet(EmptySet))
+
+    A power set of an infinite set:
+
+    >>> PowerSet(S.Reals)
+    PowerSet(Reals)
+
+    Evaluating the power set of a finite set to its explicit form:
+
+    >>> PowerSet(FiniteSet(1, 2, 3)).rewrite(FiniteSet)
+    FiniteSet(EmptySet, {1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3})
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Power_set
+
+    .. [2] https://en.wikipedia.org/wiki/Axiom_of_power_set
+    """
+    def __new__(cls, arg, evaluate=None):
+        if evaluate is None:
+            evaluate=global_parameters.evaluate
+
+        arg = _sympify(arg)
+
+        if not isinstance(arg, Set):
+            raise ValueError('{} must be a set.'.format(arg))
+
+        return super().__new__(cls, arg)
+
+    @property
+    def arg(self):
+        return self.args[0]
+
+    def _eval_rewrite_as_FiniteSet(self, *args, **kwargs):
+        arg = self.arg
+        if arg.is_FiniteSet:
+            return arg.powerset()
+        return None
+
+    @_sympifyit('other', NotImplemented)
+    def _contains(self, other):
+        if not isinstance(other, Set):
+            return None
+
+        return fuzzy_bool(self.arg.is_superset(other))
+
+    def _eval_is_subset(self, other):
+        if isinstance(other, PowerSet):
+            return self.arg.is_subset(other.arg)
+
+    def __len__(self):
+        return 2 ** len(self.arg)
+
+    def __iter__(self):
+        found = [S.EmptySet]
+        yield S.EmptySet
+
+        for x in self.arg:
+            temp = []
+            x = FiniteSet(x)
+            for y in found:
+                new = x + y
+                yield new
+                temp.append(new)
+            found.extend(temp)
+
+    @property
+    def kind(self):
+        return SetKind(self.arg.kind)

venv/lib/python3.10/site-packages/sympy/sets/setexpr.py

@@ -0,0 +1,97 @@
+from sympy.core import Expr
+from sympy.core.decorators import call_highest_priority, _sympifyit
+from .fancysets import ImageSet
+from .sets import set_add, set_sub, set_mul, set_div, set_pow, set_function
+
+
+class SetExpr(Expr):
+    """An expression that can take on values of a set.
+
+    Examples
+    ========
+
+    >>> from sympy import Interval, FiniteSet
+    >>> from sympy.sets.setexpr import SetExpr
+
+    >>> a = SetExpr(Interval(0, 5))
+    >>> b = SetExpr(FiniteSet(1, 10))
+    >>> (a + b).set
+    Union(Interval(1, 6), Interval(10, 15))
+    >>> (2*a + b).set
+    Interval(1, 20)
+    """
+    _op_priority = 11.0
+
+    def __new__(cls, setarg):
+        return Expr.__new__(cls, setarg)
+
+    set = property(lambda self: self.args[0])
+
+    def _latex(self, printer):
+        return r"SetExpr\left({}\right)".format(printer._print(self.set))
+
+    @_sympifyit('other', NotImplemented)
+    @call_highest_priority('__radd__')
+    def __add__(self, other):
+        return _setexpr_apply_operation(set_add, self, other)
+
+    @_sympifyit('other', NotImplemented)
+    @call_highest_priority('__add__')
+    def __radd__(self, other):
+        return _setexpr_apply_operation(set_add, other, self)
+
+    @_sympifyit('other', NotImplemented)
+    @call_highest_priority('__rmul__')
+    def __mul__(self, other):
+        return _setexpr_apply_operation(set_mul, self, other)
+
+    @_sympifyit('other', NotImplemented)
+    @call_highest_priority('__mul__')
+    def __rmul__(self, other):
+        return _setexpr_apply_operation(set_mul, other, self)
+
+    @_sympifyit('other', NotImplemented)
+    @call_highest_priority('__rsub__')
+    def __sub__(self, other):
+        return _setexpr_apply_operation(set_sub, self, other)
+
+    @_sympifyit('other', NotImplemented)
+    @call_highest_priority('__sub__')
+    def __rsub__(self, other):
+        return _setexpr_apply_operation(set_sub, other, self)
+
+    @_sympifyit('other', NotImplemented)
+    @call_highest_priority('__rpow__')
+    def __pow__(self, other):
+        return _setexpr_apply_operation(set_pow, self, other)
+
+    @_sympifyit('other', NotImplemented)
+    @call_highest_priority('__pow__')
+    def __rpow__(self, other):
+        return _setexpr_apply_operation(set_pow, other, self)
+
+    @_sympifyit('other', NotImplemented)
+    @call_highest_priority('__rtruediv__')
+    def __truediv__(self, other):
+        return _setexpr_apply_operation(set_div, self, other)
+
+    @_sympifyit('other', NotImplemented)
+    @call_highest_priority('__truediv__')
+    def __rtruediv__(self, other):
+        return _setexpr_apply_operation(set_div, other, self)
+
+    def _eval_func(self, func):
+        # TODO: this could be implemented straight into `imageset`:
+        res = set_function(func, self.set)
+        if res is None:
+            return SetExpr(ImageSet(func, self.set))
+        return SetExpr(res)
+
+
+def _setexpr_apply_operation(op, x, y):
+    if isinstance(x, SetExpr):
+        x = x.set
+    if isinstance(y, SetExpr):
+        y = y.set
+    out = op(x, y)
+    return SetExpr(out)

venv/lib/python3.10/site-packages/sympy/sets/sets.py

@@ -0,0 +1,2749 @@
+from typing import Any, Callable
+from functools import reduce
+from collections import defaultdict
+import inspect
+
+from sympy.core.kind import Kind, UndefinedKind, NumberKind
+from sympy.core.basic import Basic
+from sympy.core.containers import Tuple, TupleKind
+from sympy.core.decorators import sympify_method_args, sympify_return
+from sympy.core.evalf import EvalfMixin
+from sympy.core.expr import Expr
+from sympy.core.function import Lambda
+from sympy.core.logic import (FuzzyBool, fuzzy_bool, fuzzy_or, fuzzy_and,
+    fuzzy_not)
+from sympy.core.numbers import Float, Integer
+from sympy.core.operations import LatticeOp
+from sympy.core.parameters import global_parameters
+from sympy.core.relational import Eq, Ne, is_lt
+from sympy.core.singleton import Singleton, S
+from sympy.core.sorting import ordered
+from sympy.core.symbol import symbols, Symbol, Dummy, uniquely_named_symbol
+from sympy.core.sympify import _sympify, sympify, _sympy_converter
+from sympy.functions.elementary.exponential import exp, log
+from sympy.functions.elementary.miscellaneous import Max, Min
+from sympy.logic.boolalg import And, Or, Not, Xor, true, false
+from sympy.utilities.decorator import deprecated
+from sympy.utilities.exceptions import sympy_deprecation_warning
+from sympy.utilities.iterables import (iproduct, sift, roundrobin, iterable,
+                                       subsets)
+from sympy.utilities.misc import func_name, filldedent
+
+from mpmath import mpi, mpf
+
+from mpmath.libmp.libmpf import prec_to_dps
+
+
+tfn = defaultdict(lambda: None, {
+    True: S.true,
+    S.true: S.true,
+    False: S.false,
+    S.false: S.false})
+
+
+@sympify_method_args
+class Set(Basic, EvalfMixin):
+    """
+    The base class for any kind of set.
+
+    Explanation
+    ===========
+
+    This is not meant to be used directly as a container of items. It does not
+    behave like the builtin ``set``; see :class:`FiniteSet` for that.
+
+    Real intervals are represented by the :class:`Interval` class and unions of
+    sets by the :class:`Union` class. The empty set is represented by the
+    :class:`EmptySet` class and available as a singleton as ``S.EmptySet``.
+    """
+
+    __slots__ = ()
+
+    is_number = False
+    is_iterable = False
+    is_interval = False
+
+    is_FiniteSet = False
+    is_Interval = False
+    is_ProductSet = False
+    is_Union = False
+    is_Intersection: FuzzyBool = None
+    is_UniversalSet: FuzzyBool = None
+    is_Complement: FuzzyBool = None
+    is_ComplexRegion = False
+
+    is_empty: FuzzyBool = None
+    is_finite_set: FuzzyBool = None
+
+    @property  # type: ignore
+    @deprecated(
+        """
+        The is_EmptySet attribute of Set objects is deprecated.
+        Use 's is S.EmptySet" or 's.is_empty' instead.
+        """,
+        deprecated_since_version="1.5",
+        active_deprecations_target="deprecated-is-emptyset",
+    )
+    def is_EmptySet(self):
+        return None
+
+    @staticmethod
+    def _infimum_key(expr):
+        """
+        Return infimum (if possible) else S.Infinity.
+        """
+        try:
+            infimum = expr.inf
+            assert infimum.is_comparable
+            infimum = infimum.evalf()  # issue #18505
+        except (NotImplementedError,
+                AttributeError, AssertionError, ValueError):
+            infimum = S.Infinity
+        return infimum
+
+    def union(self, other):
+        """
+        Returns the union of ``self`` and ``other``.
+
+        Examples
+        ========
+
+        As a shortcut it is possible to use the ``+`` operator:
+
+        >>> from sympy import Interval, FiniteSet
+        >>> Interval(0, 1).union(Interval(2, 3))
+        Union(Interval(0, 1), Interval(2, 3))
+        >>> Interval(0, 1) + Interval(2, 3)
+        Union(Interval(0, 1), Interval(2, 3))
+        >>> Interval(1, 2, True, True) + FiniteSet(2, 3)
+        Union({3}, Interval.Lopen(1, 2))
+
+        Similarly it is possible to use the ``-`` operator for set differences:
+
+        >>> Interval(0, 2) - Interval(0, 1)
+        Interval.Lopen(1, 2)
+        >>> Interval(1, 3) - FiniteSet(2)
+        Union(Interval.Ropen(1, 2), Interval.Lopen(2, 3))
+
+        """
+        return Union(self, other)
+
+    def intersect(self, other):
+        """
+        Returns the intersection of 'self' and 'other'.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval
+
+        >>> Interval(1, 3).intersect(Interval(1, 2))
+        Interval(1, 2)
+
+        >>> from sympy import imageset, Lambda, symbols, S
+        >>> n, m = symbols('n m')
+        >>> a = imageset(Lambda(n, 2*n), S.Integers)
+        >>> a.intersect(imageset(Lambda(m, 2*m + 1), S.Integers))
+        EmptySet
+
+        """
+        return Intersection(self, other)
+
+    def intersection(self, other):
+        """
+        Alias for :meth:`intersect()`
+        """
+        return self.intersect(other)
+
+    def is_disjoint(self, other):
+        """
+        Returns True if ``self`` and ``other`` are disjoint.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval
+        >>> Interval(0, 2).is_disjoint(Interval(1, 2))
+        False
+        >>> Interval(0, 2).is_disjoint(Interval(3, 4))
+        True
+
+        References
+        ==========
+
+        .. [1] https://en.wikipedia.org/wiki/Disjoint_sets
+        """
+        return self.intersect(other) == S.EmptySet
+
+    def isdisjoint(self, other):
+        """
+        Alias for :meth:`is_disjoint()`
+        """
+        return self.is_disjoint(other)
+
+    def complement(self, universe):
+        r"""
+        The complement of 'self' w.r.t the given universe.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, S
+        >>> Interval(0, 1).complement(S.Reals)
+        Union(Interval.open(-oo, 0), Interval.open(1, oo))
+
+        >>> Interval(0, 1).complement(S.UniversalSet)
+        Complement(UniversalSet, Interval(0, 1))
+
+        """
+        return Complement(universe, self)
+
+    def _complement(self, other):
+        # this behaves as other - self
+        if isinstance(self, ProductSet) and isinstance(other, ProductSet):
+            # If self and other are disjoint then other - self == self
+            if len(self.sets) != len(other.sets):
+                return other
+
+            # There can be other ways to represent this but this gives:
+            # (A x B) - (C x D) = ((A - C) x B) U (A x (B - D))
+            overlaps = []
+            pairs = list(zip(self.sets, other.sets))
+            for n in range(len(pairs)):
+                sets = (o if i != n else o-s for i, (s, o) in enumerate(pairs))
+                overlaps.append(ProductSet(*sets))
+            return Union(*overlaps)
+
+        elif isinstance(other, Interval):
+            if isinstance(self, (Interval, FiniteSet)):
+                return Intersection(other, self.complement(S.Reals))
+
+        elif isinstance(other, Union):
+            return Union(*(o - self for o in other.args))
+
+        elif isinstance(other, Complement):
+            return Complement(other.args[0], Union(other.args[1], self), evaluate=False)
+
+        elif other is S.EmptySet:
+            return S.EmptySet
+
+        elif isinstance(other, FiniteSet):
+            sifted = sift(other, lambda x: fuzzy_bool(self.contains(x)))
+            # ignore those that are contained in self
+            return Union(FiniteSet(*(sifted[False])),
+                Complement(FiniteSet(*(sifted[None])), self, evaluate=False)
+                if sifted[None] else S.EmptySet)
+
+    def symmetric_difference(self, other):
+        """
+        Returns symmetric difference of ``self`` and ``other``.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, S
+        >>> Interval(1, 3).symmetric_difference(S.Reals)
+        Union(Interval.open(-oo, 1), Interval.open(3, oo))
+        >>> Interval(1, 10).symmetric_difference(S.Reals)
+        Union(Interval.open(-oo, 1), Interval.open(10, oo))
+
+        >>> from sympy import S, EmptySet
+        >>> S.Reals.symmetric_difference(EmptySet)
+        Reals
+
+        References
+        ==========
+        .. [1] https://en.wikipedia.org/wiki/Symmetric_difference
+
+        """
+        return SymmetricDifference(self, other)
+
+    def _symmetric_difference(self, other):
+        return Union(Complement(self, other), Complement(other, self))
+
+    @property
+    def inf(self):
+        """
+        The infimum of ``self``.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, Union
+        >>> Interval(0, 1).inf
+        0
+        >>> Union(Interval(0, 1), Interval(2, 3)).inf
+        0
+
+        """
+        return self._inf
+
+    @property
+    def _inf(self):
+        raise NotImplementedError("(%s)._inf" % self)
+
+    @property
+    def sup(self):
+        """
+        The supremum of ``self``.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, Union
+        >>> Interval(0, 1).sup
+        1
+        >>> Union(Interval(0, 1), Interval(2, 3)).sup
+        3
+
+        """
+        return self._sup
+
+    @property
+    def _sup(self):
+        raise NotImplementedError("(%s)._sup" % self)
+
+    def contains(self, other):
+        """
+        Returns a SymPy value indicating whether ``other`` is contained
+        in ``self``: ``true`` if it is, ``false`` if it is not, else
+        an unevaluated ``Contains`` expression (or, as in the case of
+        ConditionSet and a union of FiniteSet/Intervals, an expression
+        indicating the conditions for containment).
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, S
+        >>> from sympy.abc import x
+
+        >>> Interval(0, 1).contains(0.5)
+        True
+
+        As a shortcut it is possible to use the ``in`` operator, but that
+        will raise an error unless an affirmative true or false is not
+        obtained.
+
+        >>> Interval(0, 1).contains(x)
+        (0 <= x) & (x <= 1)
+        >>> x in Interval(0, 1)
+        Traceback (most recent call last):
+        ...
+        TypeError: did not evaluate to a bool: None
+
+        The result of 'in' is a bool, not a SymPy value
+
+        >>> 1 in Interval(0, 2)
+        True
+        >>> _ is S.true
+        False
+        """
+        from .contains import Contains
+        other = sympify(other, strict=True)
+
+        c = self._contains(other)
+        if isinstance(c, Contains):
+            return c
+        if c is None:
+            return Contains(other, self, evaluate=False)
+        b = tfn[c]
+        if b is None:
+            return c
+        return b
+
+    def _contains(self, other):
+        raise NotImplementedError(filldedent('''
+            (%s)._contains(%s) is not defined. This method, when
+            defined, will receive a sympified object. The method
+            should return True, False, None or something that
+            expresses what must be true for the containment of that
+            object in self to be evaluated. If None is returned
+            then a generic Contains object will be returned
+            by the ``contains`` method.''' % (self, other)))
+
+    def is_subset(self, other):
+        """
+        Returns True if ``self`` is a subset of ``other``.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval
+        >>> Interval(0, 0.5).is_subset(Interval(0, 1))
+        True
+        >>> Interval(0, 1).is_subset(Interval(0, 1, left_open=True))
+        False
+
+        """
+        if not isinstance(other, Set):
+            raise ValueError("Unknown argument '%s'" % other)
+
+        # Handle the trivial cases
+        if self == other:
+            return True
+        is_empty = self.is_empty
+        if is_empty is True:
+            return True
+        elif fuzzy_not(is_empty) and other.is_empty:
+            return False
+        if self.is_finite_set is False and other.is_finite_set:
+            return False
+
+        # Dispatch on subclass rules
+        ret = self._eval_is_subset(other)
+        if ret is not None:
+            return ret
+        ret = other._eval_is_superset(self)
+        if ret is not None:
+            return ret
+
+        # Use pairwise rules from multiple dispatch
+        from sympy.sets.handlers.issubset import is_subset_sets
+        ret = is_subset_sets(self, other)
+        if ret is not None:
+            return ret
+
+        # Fall back on computing the intersection
+        # XXX: We shouldn't do this. A query like this should be handled
+        # without evaluating new Set objects. It should be the other way round
+        # so that the intersect method uses is_subset for evaluation.
+        if self.intersect(other) == self:
+            return True
+
+    def _eval_is_subset(self, other):
+        '''Returns a fuzzy bool for whether self is a subset of other.'''
+        return None
+
+    def _eval_is_superset(self, other):
+        '''Returns a fuzzy bool for whether self is a subset of other.'''
+        return None
+
+    # This should be deprecated:
+    def issubset(self, other):
+        """
+        Alias for :meth:`is_subset()`
+        """
+        return self.is_subset(other)
+
+    def is_proper_subset(self, other):
+        """
+        Returns True if ``self`` is a proper subset of ``other``.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval
+        >>> Interval(0, 0.5).is_proper_subset(Interval(0, 1))
+        True
+        >>> Interval(0, 1).is_proper_subset(Interval(0, 1))
+        False
+
+        """
+        if isinstance(other, Set):
+            return self != other and self.is_subset(other)
+        else:
+            raise ValueError("Unknown argument '%s'" % other)
+
+    def is_superset(self, other):
+        """
+        Returns True if ``self`` is a superset of ``other``.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval
+        >>> Interval(0, 0.5).is_superset(Interval(0, 1))
+        False
+        >>> Interval(0, 1).is_superset(Interval(0, 1, left_open=True))
+        True
+
+        """
+        if isinstance(other, Set):
+            return other.is_subset(self)
+        else:
+            raise ValueError("Unknown argument '%s'" % other)
+
+    # This should be deprecated:
+    def issuperset(self, other):
+        """
+        Alias for :meth:`is_superset()`
+        """
+        return self.is_superset(other)
+
+    def is_proper_superset(self, other):
+        """
+        Returns True if ``self`` is a proper superset of ``other``.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval
+        >>> Interval(0, 1).is_proper_superset(Interval(0, 0.5))
+        True
+        >>> Interval(0, 1).is_proper_superset(Interval(0, 1))
+        False
+
+        """
+        if isinstance(other, Set):
+            return self != other and self.is_superset(other)
+        else:
+            raise ValueError("Unknown argument '%s'" % other)
+
+    def _eval_powerset(self):
+        from .powerset import PowerSet
+        return PowerSet(self)
+
+    def powerset(self):
+        """
+        Find the Power set of ``self``.
+
+        Examples
+        ========
+
+        >>> from sympy import EmptySet, FiniteSet, Interval
+
+        A power set of an empty set:
+
+        >>> A = EmptySet
+        >>> A.powerset()
+        {EmptySet}
+
+        A power set of a finite set:
+
+        >>> A = FiniteSet(1, 2)
+        >>> a, b, c = FiniteSet(1), FiniteSet(2), FiniteSet(1, 2)
+        >>> A.powerset() == FiniteSet(a, b, c, EmptySet)
+        True
+
+        A power set of an interval:
+
+        >>> Interval(1, 2).powerset()
+        PowerSet(Interval(1, 2))
+
+        References
+        ==========
+
+        .. [1] https://en.wikipedia.org/wiki/Power_set
+
+        """
+        return self._eval_powerset()
+
+    @property
+    def measure(self):
+        """
+        The (Lebesgue) measure of ``self``.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, Union
+        >>> Interval(0, 1).measure
+        1
+        >>> Union(Interval(0, 1), Interval(2, 3)).measure
+        2
+
+        """
+        return self._measure
+
+    @property
+    def kind(self):
+        """
+        The kind of a Set
+
+        Explanation
+        ===========
+
+        Any :class:`Set` will have kind :class:`SetKind` which is
+        parametrised by the kind of the elements of the set. For example
+        most sets are sets of numbers and will have kind
+        ``SetKind(NumberKind)``. If elements of sets are different in kind than
+        their kind will ``SetKind(UndefinedKind)``. See
+        :class:`sympy.core.kind.Kind` for an explanation of the kind system.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, Matrix, FiniteSet, EmptySet, ProductSet, PowerSet
+
+        >>> FiniteSet(Matrix([1, 2])).kind
+        SetKind(MatrixKind(NumberKind))
+
+        >>> Interval(1, 2).kind
+        SetKind(NumberKind)
+
+        >>> EmptySet.kind
+        SetKind()
+
+        A :class:`sympy.sets.powerset.PowerSet` is a set of sets:
+
+        >>> PowerSet({1, 2, 3}).kind
+        SetKind(SetKind(NumberKind))
+
+        A :class:`ProductSet` represents the set of tuples of elements of
+        other sets. Its kind is :class:`sympy.core.containers.TupleKind`
+        parametrised by the kinds of the elements of those sets:
+
+        >>> p = ProductSet(FiniteSet(1, 2), FiniteSet(3, 4))
+        >>> list(p)
+        [(1, 3), (2, 3), (1, 4), (2, 4)]
+        >>> p.kind
+        SetKind(TupleKind(NumberKind, NumberKind))
+
+        When all elements of the set do not have same kind, the kind
+        will be returned as ``SetKind(UndefinedKind)``:
+
+        >>> FiniteSet(0, Matrix([1, 2])).kind
+        SetKind(UndefinedKind)
+
+        The kind of the elements of a set are given by the ``element_kind``
+        attribute of ``SetKind``:
+
+        >>> Interval(1, 2).kind.element_kind
+        NumberKind
+
+        See Also
+        ========
+
+        NumberKind
+        sympy.core.kind.UndefinedKind
+        sympy.core.containers.TupleKind
+        MatrixKind
+        sympy.matrices.expressions.sets.MatrixSet
+        sympy.sets.conditionset.ConditionSet
+        Rationals
+        Naturals
+        Integers
+        sympy.sets.fancysets.ImageSet
+        sympy.sets.fancysets.Range
+        sympy.sets.fancysets.ComplexRegion
+        sympy.sets.powerset.PowerSet
+        sympy.sets.sets.ProductSet
+        sympy.sets.sets.Interval
+        sympy.sets.sets.Union
+        sympy.sets.sets.Intersection
+        sympy.sets.sets.Complement
+        sympy.sets.sets.EmptySet
+        sympy.sets.sets.UniversalSet
+        sympy.sets.sets.FiniteSet
+        sympy.sets.sets.SymmetricDifference
+        sympy.sets.sets.DisjointUnion
+        """
+        return self._kind()
+
+    @property
+    def boundary(self):
+        """
+        The boundary or frontier of a set.
+
+        Explanation
+        ===========
+
+        A point x is on the boundary of a set S if
+
+        1.  x is in the closure of S.
+            I.e. Every neighborhood of x contains a point in S.
+        2.  x is not in the interior of S.
+            I.e. There does not exist an open set centered on x contained
+            entirely within S.
+
+        There are the points on the outer rim of S.  If S is open then these
+        points need not actually be contained within S.
+
+        For example, the boundary of an interval is its start and end points.
+        This is true regardless of whether or not the interval is open.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval
+        >>> Interval(0, 1).boundary
+        {0, 1}
+        >>> Interval(0, 1, True, False).boundary
+        {0, 1}
+        """
+        return self._boundary
+
+    @property
+    def is_open(self):
+        """
+        Property method to check whether a set is open.
+
+        Explanation
+        ===========
+
+        A set is open if and only if it has an empty intersection with its
+        boundary. In particular, a subset A of the reals is open if and only
+        if each one of its points is contained in an open interval that is a
+        subset of A.
+
+        Examples
+        ========
+        >>> from sympy import S
+        >>> S.Reals.is_open
+        True
+        >>> S.Rationals.is_open
+        False
+        """
+        return Intersection(self, self.boundary).is_empty
+
+    @property
+    def is_closed(self):
+        """
+        A property method to check whether a set is closed.
+
+        Explanation
+        ===========
+
+        A set is closed if its complement is an open set. The closedness of a
+        subset of the reals is determined with respect to R and its standard
+        topology.
+
+        Examples
+        ========
+        >>> from sympy import Interval
+        >>> Interval(0, 1).is_closed
+        True
+        """
+        return self.boundary.is_subset(self)
+
+    @property
+    def closure(self):
+        """
+        Property method which returns the closure of a set.
+        The closure is defined as the union of the set itself and its
+        boundary.
+
+        Examples
+        ========
+        >>> from sympy import S, Interval
+        >>> S.Reals.closure
+        Reals
+        >>> Interval(0, 1).closure
+        Interval(0, 1)
+        """
+        return self + self.boundary
+
+    @property
+    def interior(self):
+        """
+        Property method which returns the interior of a set.
+        The interior of a set S consists all points of S that do not
+        belong to the boundary of S.
+
+        Examples
+        ========
+        >>> from sympy import Interval
+        >>> Interval(0, 1).interior
+        Interval.open(0, 1)
+        >>> Interval(0, 1).boundary.interior
+        EmptySet
+        """
+        return self - self.boundary
+
+    @property
+    def _boundary(self):
+        raise NotImplementedError()
+
+    @property
+    def _measure(self):
+        raise NotImplementedError("(%s)._measure" % self)
+
+    def _kind(self):
+        return SetKind(UndefinedKind)
+
+    def _eval_evalf(self, prec):
+        dps = prec_to_dps(prec)
+        return self.func(*[arg.evalf(n=dps) for arg in self.args])
+
+    @sympify_return([('other', 'Set')], NotImplemented)
+    def __add__(self, other):
+        return self.union(other)
+
+    @sympify_return([('other', 'Set')], NotImplemented)
+    def __or__(self, other):
+        return self.union(other)
+
+    @sympify_return([('other', 'Set')], NotImplemented)
+    def __and__(self, other):
+        return self.intersect(other)
+
+    @sympify_return([('other', 'Set')], NotImplemented)
+    def __mul__(self, other):
+        return ProductSet(self, other)
+
+    @sympify_return([('other', 'Set')], NotImplemented)
+    def __xor__(self, other):
+        return SymmetricDifference(self, other)
+
+    @sympify_return([('exp', Expr)], NotImplemented)
+    def __pow__(self, exp):
+        if not (exp.is_Integer and exp >= 0):
+            raise ValueError("%s: Exponent must be a positive Integer" % exp)
+        return ProductSet(*[self]*exp)
+
+    @sympify_return([('other', 'Set')], NotImplemented)
+    def __sub__(self, other):
+        return Complement(self, other)
+
+    def __contains__(self, other):
+        other = _sympify(other)
+        c = self._contains(other)
+        b = tfn[c]
+        if b is None:
+            # x in y must evaluate to T or F; to entertain a None
+            # result with Set use y.contains(x)
+            raise TypeError('did not evaluate to a bool: %r' % c)
+        return b
+
+
+class ProductSet(Set):
+    """
+    Represents a Cartesian Product of Sets.
+
+    Explanation
+    ===========
+
+    Returns a Cartesian product given several sets as either an iterable
+    or individual arguments.
+
+    Can use ``*`` operator on any sets for convenient shorthand.
+
+    Examples
+    ========
+
+    >>> from sympy import Interval, FiniteSet, ProductSet
+    >>> I = Interval(0, 5); S = FiniteSet(1, 2, 3)
+    >>> ProductSet(I, S)
+    ProductSet(Interval(0, 5), {1, 2, 3})
+
+    >>> (2, 2) in ProductSet(I, S)
+    True
+
+    >>> Interval(0, 1) * Interval(0, 1) # The unit square
+    ProductSet(Interval(0, 1), Interval(0, 1))
+
+    >>> coin = FiniteSet('H', 'T')
+    >>> set(coin**2)
+    {(H, H), (H, T), (T, H), (T, T)}
+
+    The Cartesian product is not commutative or associative e.g.:
+
+    >>> I*S == S*I
+    False
+    >>> (I*I)*I == I*(I*I)
+    False
+
+    Notes
+    =====
+
+    - Passes most operations down to the argument sets
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Cartesian_product
+    """
+    is_ProductSet = True
+
+    def __new__(cls, *sets, **assumptions):
+        if len(sets) == 1 and iterable(sets[0]) and not isinstance(sets[0], (Set, set)):
+            sympy_deprecation_warning(
+                """
+ProductSet(iterable) is deprecated. Use ProductSet(*iterable) instead.
+                """,
+                deprecated_since_version="1.5",
+                active_deprecations_target="deprecated-productset-iterable",
+            )
+            sets = tuple(sets[0])
+
+        sets = [sympify(s) for s in sets]
+
+        if not all(isinstance(s, Set) for s in sets):
+            raise TypeError("Arguments to ProductSet should be of type Set")
+
+        # Nullary product of sets is *not* the empty set
+        if len(sets) == 0:
+            return FiniteSet(())
+
+        if S.EmptySet in sets:
+            return S.EmptySet
+
+        return Basic.__new__(cls, *sets, **assumptions)
+
+    @property
+    def sets(self):
+        return self.args
+
+    def flatten(self):
+        def _flatten(sets):
+            for s in sets:
+                if s.is_ProductSet:
+                    yield from _flatten(s.sets)
+                else:
+                    yield s
+        return ProductSet(*_flatten(self.sets))
+
+
+
+    def _contains(self, element):
+        """
+        ``in`` operator for ProductSets.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval
+        >>> (2, 3) in Interval(0, 5) * Interval(0, 5)
+        True
+
+        >>> (10, 10) in Interval(0, 5) * Interval(0, 5)
+        False
+
+        Passes operation on to constituent sets
+        """
+        if element.is_Symbol:
+            return None
+
+        if not isinstance(element, Tuple) or len(element) != len(self.sets):
+            return False
+
+        return fuzzy_and(s._contains(e) for s, e in zip(self.sets, element))
+
+    def as_relational(self, *symbols):
+        symbols = [_sympify(s) for s in symbols]
+        if len(symbols) != len(self.sets) or not all(
+                i.is_Symbol for i in symbols):
+            raise ValueError(
+                'number of symbols must match the number of sets')
+        return And(*[s.as_relational(i) for s, i in zip(self.sets, symbols)])
+
+    @property
+    def _boundary(self):
+        return Union(*(ProductSet(*(b + b.boundary if i != j else b.boundary
+                                for j, b in enumerate(self.sets)))
+                                for i, a in enumerate(self.sets)))
+
+    @property
+    def is_iterable(self):
+        """
+        A property method which tests whether a set is iterable or not.
+        Returns True if set is iterable, otherwise returns False.
+
+        Examples
+        ========
+
+        >>> from sympy import FiniteSet, Interval
+        >>> I = Interval(0, 1)
+        >>> A = FiniteSet(1, 2, 3, 4, 5)
+        >>> I.is_iterable
+        False
+        >>> A.is_iterable
+        True
+
+        """
+        return all(set.is_iterable for set in self.sets)
+
+    def __iter__(self):
+        """
+        A method which implements is_iterable property method.
+        If self.is_iterable returns True (both constituent sets are iterable),
+        then return the Cartesian Product. Otherwise, raise TypeError.
+        """
+        return iproduct(*self.sets)
+
+    @property
+    def is_empty(self):
+        return fuzzy_or(s.is_empty for s in self.sets)
+
+    @property
+    def is_finite_set(self):
+        all_finite = fuzzy_and(s.is_finite_set for s in self.sets)
+        return fuzzy_or([self.is_empty, all_finite])
+
+    @property
+    def _measure(self):
+        measure = 1
+        for s in self.sets:
+            measure *= s.measure
+        return measure
+
+    def _kind(self):
+        return SetKind(TupleKind(*(i.kind.element_kind for i in self.args)))
+
+    def __len__(self):
+        return reduce(lambda a, b: a*b, (len(s) for s in self.args))
+
+    def __bool__(self):
+        return all(self.sets)
+
+
+class Interval(Set):
+    """
+    Represents a real interval as a Set.
+
+    Usage:
+        Returns an interval with end points ``start`` and ``end``.
+
+        For ``left_open=True`` (default ``left_open`` is ``False``) the interval
+        will be open on the left. Similarly, for ``right_open=True`` the interval
+        will be open on the right.
+
+    Examples
+    ========
+
+    >>> from sympy import Symbol, Interval
+    >>> Interval(0, 1)
+    Interval(0, 1)
+    >>> Interval.Ropen(0, 1)
+    Interval.Ropen(0, 1)
+    >>> Interval.Ropen(0, 1)
+    Interval.Ropen(0, 1)
+    >>> Interval.Lopen(0, 1)
+    Interval.Lopen(0, 1)
+    >>> Interval.open(0, 1)
+    Interval.open(0, 1)
+
+    >>> a = Symbol('a', real=True)
+    >>> Interval(0, a)
+    Interval(0, a)
+
+    Notes
+    =====
+    - Only real end points are supported
+    - ``Interval(a, b)`` with $a > b$ will return the empty set
+    - Use the ``evalf()`` method to turn an Interval into an mpmath
+      ``mpi`` interval instance
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Interval_%28mathematics%29
+    """
+    is_Interval = True
+
+    def __new__(cls, start, end, left_open=False, right_open=False):
+
+        start = _sympify(start)
+        end = _sympify(end)
+        left_open = _sympify(left_open)
+        right_open = _sympify(right_open)
+
+        if not all(isinstance(a, (type(true), type(false)))
+            for a in [left_open, right_open]):
+            raise NotImplementedError(
+                "left_open and right_open can have only true/false values, "
+                "got %s and %s" % (left_open, right_open))
+
+        # Only allow real intervals
+        if fuzzy_not(fuzzy_and(i.is_extended_real for i in (start, end, end-start))):
+            raise ValueError("Non-real intervals are not supported")
+
+        # evaluate if possible
+        if is_lt(end, start):
+            return S.EmptySet
+        elif (end - start).is_negative:
+            return S.EmptySet
+
+        if end == start and (left_open or right_open):
+            return S.EmptySet
+        if end == start and not (left_open or right_open):
+            if start is S.Infinity or start is S.NegativeInfinity:
+                return S.EmptySet
+            return FiniteSet(end)
+
+        # Make sure infinite interval end points are open.
+        if start is S.NegativeInfinity:
+            left_open = true
+        if end is S.Infinity:
+            right_open = true
+        if start == S.Infinity or end == S.NegativeInfinity:
+            return S.EmptySet
+
+        return Basic.__new__(cls, start, end, left_open, right_open)
+
+    @property
+    def start(self):
+        """
+        The left end point of the interval.
+
+        This property takes the same value as the ``inf`` property.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval
+        >>> Interval(0, 1).start
+        0
+
+        """
+        return self._args[0]
+
+    @property
+    def end(self):
+        """
+        The right end point of the interval.
+
+        This property takes the same value as the ``sup`` property.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval
+        >>> Interval(0, 1).end
+        1
+
+        """
+        return self._args[1]
+
+    @property
+    def left_open(self):
+        """
+        True if interval is left-open.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval
+        >>> Interval(0, 1, left_open=True).left_open
+        True
+        >>> Interval(0, 1, left_open=False).left_open
+        False
+
+        """
+        return self._args[2]
+
+    @property
+    def right_open(self):
+        """
+        True if interval is right-open.
+
+        Examples
+        ========
+
+        >>> from sympy import Interval
+        >>> Interval(0, 1, right_open=True).right_open
+        True
+        >>> Interval(0, 1, right_open=False).right_open
+        False
+
+        """
+        return self._args[3]
+
+    @classmethod
+    def open(cls, a, b):
+        """Return an interval including neither boundary."""
+        return cls(a, b, True, True)
+
+    @classmethod
+    def Lopen(cls, a, b):
+        """Return an interval not including the left boundary."""
+        return cls(a, b, True, False)
+
+    @classmethod
+    def Ropen(cls, a, b):
+        """Return an interval not including the right boundary."""
+        return cls(a, b, False, True)
+
+    @property
+    def _inf(self):
+        return self.start
+
+    @property
+    def _sup(self):
+        return self.end
+
+    @property
+    def left(self):
+        return self.start
+
+    @property
+    def right(self):
+        return self.end
+
+    @property
+    def is_empty(self):
+        if self.left_open or self.right_open:
+            cond = self.start >= self.end  # One/both bounds open
+        else:
+            cond = self.start > self.end  # Both bounds closed
+        return fuzzy_bool(cond)
+
+    @property
+    def is_finite_set(self):
+        return self.measure.is_zero
+
+    def _complement(self, other):
+        if other == S.Reals:
+            a = Interval(S.NegativeInfinity, self.start,
+                         True, not self.left_open)
+            b = Interval(self.end, S.Infinity, not self.right_open, True)
+            return Union(a, b)
+
+        if isinstance(other, FiniteSet):
+            nums = [m for m in other.args if m.is_number]
+            if nums == []:
+                return None
+
+        return Set._complement(self, other)
+
+    @property
+    def _boundary(self):
+        finite_points = [p for p in (self.start, self.end)
+                         if abs(p) != S.Infinity]
+        return FiniteSet(*finite_points)
+
+    def _contains(self, other):
+        if (not isinstance(other, Expr) or other is S.NaN
+            or other.is_real is False or other.has(S.ComplexInfinity)):
+                # if an expression has zoo it will be zoo or nan
+                # and neither of those is real
+                return false
+
+        if self.start is S.NegativeInfinity and self.end is S.Infinity:
+            if other.is_real is not None:
+                return other.is_real
+
+        d = Dummy()
+        return self.as_relational(d).subs(d, other)
+
+    def as_relational(self, x):
+        """Rewrite an interval in terms of inequalities and logic operators."""
+        x = sympify(x)
+        if self.right_open:
+            right = x < self.end
+        else:
+            right = x <= self.end
+        if self.left_open:
+            left = self.start < x
+        else:
+            left = self.start <= x
+        return And(left, right)
+
+    @property
+    def _measure(self):
+        return self.end - self.start
+
+    def _kind(self):
+        return SetKind(NumberKind)
+
+    def to_mpi(self, prec=53):
+        return mpi(mpf(self.start._eval_evalf(prec)),
+            mpf(self.end._eval_evalf(prec)))
+
+    def _eval_evalf(self, prec):
+        return Interval(self.left._evalf(prec), self.right._evalf(prec),
+            left_open=self.left_open, right_open=self.right_open)
+
+    def _is_comparable(self, other):
+        is_comparable = self.start.is_comparable
+        is_comparable &= self.end.is_comparable
+        is_comparable &= other.start.is_comparable
+        is_comparable &= other.end.is_comparable
+
+        return is_comparable
+
+    @property
+    def is_left_unbounded(self):
+        """Return ``True`` if the left endpoint is negative infinity. """
+        return self.left is S.NegativeInfinity or self.left == Float("-inf")
+
+    @property
+    def is_right_unbounded(self):
+        """Return ``True`` if the right endpoint is positive infinity. """
+        return self.right is S.Infinity or self.right == Float("+inf")
+
+    def _eval_Eq(self, other):
+        if not isinstance(other, Interval):
+            if isinstance(other, FiniteSet):
+                return false
+            elif isinstance(other, Set):
+                return None
+            return false
+
+
+class Union(Set, LatticeOp):
+    """
+    Represents a union of sets as a :class:`Set`.
+
+    Examples
+    ========
+
+    >>> from sympy import Union, Interval
+    >>> Union(Interval(1, 2), Interval(3, 4))
+    Union(Interval(1, 2), Interval(3, 4))
+
+    The Union constructor will always try to merge overlapping intervals,
+    if possible. For example:
+
+    >>> Union(Interval(1, 2), Interval(2, 3))
+    Interval(1, 3)
+
+    See Also
+    ========
+
+    Intersection
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Union_%28set_theory%29
+    """
+    is_Union = True
+
+    @property
+    def identity(self):
+        return S.EmptySet
+
+    @property
+    def zero(self):
+        return S.UniversalSet
+
+    def __new__(cls, *args, **kwargs):
+        evaluate = kwargs.get('evaluate', global_parameters.evaluate)
+
+        # flatten inputs to merge intersections and iterables
+        args = _sympify(args)
+
+        # Reduce sets using known rules
+        if evaluate:
+            args = list(cls._new_args_filter(args))
+            return simplify_union(args)
+
+        args = list(ordered(args, Set._infimum_key))
+
+        obj = Basic.__new__(cls, *args)
+        obj._argset = frozenset(args)
+        return obj
+
+    @property
+    def args(self):
+        return self._args
+
+    def _complement(self, universe):
+        # DeMorgan's Law
+        return Intersection(s.complement(universe) for s in self.args)
+
+    @property
+    def _inf(self):
+        # We use Min so that sup is meaningful in combination with symbolic
+        # interval end points.
+        return Min(*[set.inf for set in self.args])
+
+    @property
+    def _sup(self):
+        # We use Max so that sup is meaningful in combination with symbolic
+        # end points.
+        return Max(*[set.sup for set in self.args])
+
+    @property
+    def is_empty(self):
+        return fuzzy_and(set.is_empty for set in self.args)
+
+    @property
+    def is_finite_set(self):
+        return fuzzy_and(set.is_finite_set for set in self.args)
+
+    @property
+    def _measure(self):
+        # Measure of a union is the sum of the measures of the sets minus
+        # the sum of their pairwise intersections plus the sum of their
+        # triple-wise intersections minus ... etc...
+
+        # Sets is a collection of intersections and a set of elementary
+        # sets which made up those intersections (called "sos" for set of sets)
+        # An example element might of this list might be:
+        #    ( {A,B,C}, A.intersect(B).intersect(C) )
+
+        # Start with just elementary sets (  ({A}, A), ({B}, B), ... )
+        # Then get and subtract (  ({A,B}, (A int B), ... ) while non-zero
+        sets = [(FiniteSet(s), s) for s in self.args]
+        measure = 0
+        parity = 1
+        while sets:
+            # Add up the measure of these sets and add or subtract it to total
+            measure += parity * sum(inter.measure for sos, inter in sets)
+
+            # For each intersection in sets, compute the intersection with every
+            # other set not already part of the intersection.
+            sets = ((sos + FiniteSet(newset), newset.intersect(intersection))
+                    for sos, intersection in sets for newset in self.args
+                    if newset not in sos)
+
+            # Clear out sets with no measure
+            sets = [(sos, inter) for sos, inter in sets if inter.measure != 0]
+
+            # Clear out duplicates
+            sos_list = []
+            sets_list = []
+            for _set in sets:
+                if _set[0] in sos_list:
+                    continue
+                else:
+                    sos_list.append(_set[0])
+                    sets_list.append(_set)
+            sets = sets_list
+
+            # Flip Parity - next time subtract/add if we added/subtracted here
+            parity *= -1
+        return measure
+
+    def _kind(self):
+        kinds = tuple(arg.kind for arg in self.args if arg is not S.EmptySet)
+        if not kinds:
+            return SetKind()
+        elif all(i == kinds[0] for i in kinds):
+            return kinds[0]
+        else:
+            return SetKind(UndefinedKind)
+
+    @property
+    def _boundary(self):
+        def boundary_of_set(i):
+            """ The boundary of set i minus interior of all other sets """
+            b = self.args[i].boundary
+            for j, a in enumerate(self.args):
+                if j != i:
+                    b = b - a.interior
+            return b
+        return Union(*map(boundary_of_set, range(len(self.args))))
+
+    def _contains(self, other):
+        return Or(*[s.contains(other) for s in self.args])
+
+    def is_subset(self, other):
+        return fuzzy_and(s.is_subset(other) for s in self.args)
+
+    def as_relational(self, symbol):
+        """Rewrite a Union in terms of equalities and logic operators. """
+        if (len(self.args) == 2 and
+                all(isinstance(i, Interval) for i in self.args)):
+            # optimization to give 3 args as (x > 1) & (x < 5) & Ne(x, 3)
+            # instead of as 4, ((1 <= x) & (x < 3)) | ((x <= 5) & (3 < x))
+            # XXX: This should be ideally be improved to handle any number of
+            # intervals and also not to assume that the intervals are in any
+            # particular sorted order.
+            a, b = self.args
+            if a.sup == b.inf and a.right_open and b.left_open:
+                mincond = symbol > a.inf if a.left_open else symbol >= a.inf
+                maxcond = symbol < b.sup if b.right_open else symbol <= b.sup
+                necond = Ne(symbol, a.sup)
+                return And(necond, mincond, maxcond)
+        return Or(*[i.as_relational(symbol) for i in self.args])
+
+    @property
+    def is_iterable(self):
+        return all(arg.is_iterable for arg in self.args)
+
+    def __iter__(self):
+        return roundrobin(*(iter(arg) for arg in self.args))
+
+
+class Intersection(Set, LatticeOp):
+    """
+    Represents an intersection of sets as a :class:`Set`.
+
+    Examples
+    ========
+
+    >>> from sympy import Intersection, Interval
+    >>> Intersection(Interval(1, 3), Interval(2, 4))
+    Interval(2, 3)
+
+    We often use the .intersect method
+
+    >>> Interval(1,3).intersect(Interval(2,4))
+    Interval(2, 3)
+
+    See Also
+    ========
+
+    Union
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Intersection_%28set_theory%29
+    """
+    is_Intersection = True
+
+    @property
+    def identity(self):
+        return S.UniversalSet
+
+    @property
+    def zero(self):
+        return S.EmptySet
+
+    def __new__(cls, *args, **kwargs):
+        evaluate = kwargs.get('evaluate', global_parameters.evaluate)
+
+        # flatten inputs to merge intersections and iterables
+        args = list(ordered(set(_sympify(args))))
+
+        # Reduce sets using known rules
+        if evaluate:
+            args = list(cls._new_args_filter(args))
+            return simplify_intersection(args)
+
+        args = list(ordered(args, Set._infimum_key))
+
+        obj = Basic.__new__(cls, *args)
+        obj._argset = frozenset(args)
+        return obj
+
+    @property
+    def args(self):
+        return self._args
+
+    @property
+    def is_iterable(self):
+        return any(arg.is_iterable for arg in self.args)
+
+    @property
+    def is_finite_set(self):
+        if fuzzy_or(arg.is_finite_set for arg in self.args):
+            return True
+
+    def _kind(self):
+        kinds = tuple(arg.kind for arg in self.args if arg is not S.UniversalSet)
+        if not kinds:
+            return SetKind(UndefinedKind)
+        elif all(i == kinds[0] for i in kinds):
+            return kinds[0]
+        else:
+            return SetKind()
+
+    @property
+    def _inf(self):
+        raise NotImplementedError()
+
+    @property
+    def _sup(self):
+        raise NotImplementedError()
+
+    def _contains(self, other):
+        return And(*[set.contains(other) for set in self.args])
+
+    def __iter__(self):
+        sets_sift = sift(self.args, lambda x: x.is_iterable)
+
+        completed = False
+        candidates = sets_sift[True] + sets_sift[None]
+
+        finite_candidates, others = [], []
+        for candidate in candidates:
+            length = None
+            try:
+                length = len(candidate)
+            except TypeError:
+                others.append(candidate)
+
+            if length is not None:
+                finite_candidates.append(candidate)
+        finite_candidates.sort(key=len)
+
+        for s in finite_candidates + others:
+            other_sets = set(self.args) - {s}
+            other = Intersection(*other_sets, evaluate=False)
+            completed = True
+            for x in s:
+                try:
+                    if x in other:
+                        yield x
+                except TypeError:
+                    completed = False
+            if completed:
+                return
+
+        if not completed:
+            if not candidates:
+                raise TypeError("None of the constituent sets are iterable")
+            raise TypeError(
+                "The computation had not completed because of the "
+                "undecidable set membership is found in every candidates.")
+
+    @staticmethod
+    def _handle_finite_sets(args):
+        '''Simplify intersection of one or more FiniteSets and other sets'''
+
+        # First separate the FiniteSets from the others
+        fs_args, others = sift(args, lambda x: x.is_FiniteSet, binary=True)
+
+        # Let the caller handle intersection of non-FiniteSets
+        if not fs_args:
+            return
+
+        # Convert to Python sets and build the set of all elements
+        fs_sets = [set(fs) for fs in fs_args]
+        all_elements = reduce(lambda a, b: a | b, fs_sets, set())
+
+        # Extract elements that are definitely in or definitely not in the
+        # intersection. Here we check contains for all of args.
+        definite = set()
+        for e in all_elements:
+            inall = fuzzy_and(s.contains(e) for s in args)
+            if inall is True:
+                definite.add(e)
+            if inall is not None:
+                for s in fs_sets:
+                    s.discard(e)
+
+        # At this point all elements in all of fs_sets are possibly in the
+        # intersection. In some cases this is because they are definitely in
+        # the intersection of the finite sets but it's not clear if they are
+        # members of others. We might have {m, n}, {m}, and Reals where we
+        # don't know if m or n is real. We want to remove n here but it is
+        # possibly in because it might be equal to m. So what we do now is
+        # extract the elements that are definitely in the remaining finite
+        # sets iteratively until we end up with {n}, {}. At that point if we
+        # get any empty set all remaining elements are discarded.
+
+        fs_elements = reduce(lambda a, b: a | b, fs_sets, set())
+
+        # Need fuzzy containment testing
+        fs_symsets = [FiniteSet(*s) for s in fs_sets]
+
+        while fs_elements:
+            for e in fs_elements:
+                infs = fuzzy_and(s.contains(e) for s in fs_symsets)
+                if infs is True:
+                    definite.add(e)
+                if infs is not None:
+                    for n, s in enumerate(fs_sets):
+                        # Update Python set and FiniteSet
+                        if e in s:
+                            s.remove(e)
+                            fs_symsets[n] = FiniteSet(*s)
+                    fs_elements.remove(e)
+                    break
+            # If we completed the for loop without removing anything we are
+            # done so quit the outer while loop
+            else:
+                break
+
+        # If any of the sets of remainder elements is empty then we discard
+        # all of them for the intersection.
+        if not all(fs_sets):
+            fs_sets = [set()]
+
+        # Here we fold back the definitely included elements into each fs.
+        # Since they are definitely included they must have been members of
+        # each FiniteSet to begin with. We could instead fold these in with a
+        # Union at the end to get e.g. {3}|({x}&{y}) rather than {3,x}&{3,y}.
+        if definite:
+            fs_sets = [fs | definite for fs in fs_sets]
+
+        if fs_sets == [set()]:
+            return S.EmptySet
+
+        sets = [FiniteSet(*s) for s in fs_sets]
+
+        # Any set in others is redundant if it contains all the elements that
+        # are in the finite sets so we don't need it in the Intersection
+        all_elements = reduce(lambda a, b: a | b, fs_sets, set())
+        is_redundant = lambda o: all(fuzzy_bool(o.contains(e)) for e in all_elements)
+        others = [o for o in others if not is_redundant(o)]
+
+        if others:
+            rest = Intersection(*others)
+            # XXX: Maybe this shortcut should be at the beginning. For large
+            # FiniteSets it could much more efficient to process the other
+            # sets first...
+            if rest is S.EmptySet:
+                return S.EmptySet
+            # Flatten the Intersection
+            if rest.is_Intersection:
+                sets.extend(rest.args)
+            else:
+                sets.append(rest)
+
+        if len(sets) == 1:
+            return sets[0]
+        else:
+            return Intersection(*sets, evaluate=False)
+
+    def as_relational(self, symbol):
+        """Rewrite an Intersection in terms of equalities and logic operators"""
+        return And(*[set.as_relational(symbol) for set in self.args])
+
+
+class Complement(Set):
+    r"""Represents the set difference or relative complement of a set with
+    another set.
+
+    $$A - B = \{x \in A \mid x \notin B\}$$
+
+
+    Examples
+    ========
+
+    >>> from sympy import Complement, FiniteSet
+    >>> Complement(FiniteSet(0, 1, 2), FiniteSet(1))
+    {0, 2}
+
+    See Also
+    =========
+
+    Intersection, Union
+
+    References
+    ==========
+
+    .. [1] https://mathworld.wolfram.com/ComplementSet.html
+    """
+
+    is_Complement = True
+
+    def __new__(cls, a, b, evaluate=True):
+        a, b = map(_sympify, (a, b))
+        if evaluate:
+            return Complement.reduce(a, b)
+
+        return Basic.__new__(cls, a, b)
+
+    @staticmethod
+    def reduce(A, B):
+        """
+        Simplify a :class:`Complement`.
+
+        """
+        if B == S.UniversalSet or A.is_subset(B):
+            return S.EmptySet
+
+        if isinstance(B, Union):
+            return Intersection(*(s.complement(A) for s in B.args))
+
+        result = B._complement(A)
+        if result is not None:
+            return result
+        else:
+            return Complement(A, B, evaluate=False)
+
+    def _contains(self, other):
+        A = self.args[0]
+        B = self.args[1]
+        return And(A.contains(other), Not(B.contains(other)))
+
+    def as_relational(self, symbol):
+        """Rewrite a complement in terms of equalities and logic
+        operators"""
+        A, B = self.args
+
+        A_rel = A.as_relational(symbol)
+        B_rel = Not(B.as_relational(symbol))
+
+        return And(A_rel, B_rel)
+
+    def _kind(self):
+        return self.args[0].kind
+
+    @property
+    def is_iterable(self):
+        if self.args[0].is_iterable:
+            return True
+
+    @property
+    def is_finite_set(self):
+        A, B = self.args
+        a_finite = A.is_finite_set
+        if a_finite is True:
+            return True
+        elif a_finite is False and B.is_finite_set:
+            return False
+
+    def __iter__(self):
+        A, B = self.args
+        for a in A:
+            if a not in B:
+                    yield a
+            else:
+                continue
+
+
+class EmptySet(Set, metaclass=Singleton):
+    """
+    Represents the empty set. The empty set is available as a singleton
+    as ``S.EmptySet``.
+
+    Examples
+    ========
+
+    >>> from sympy import S, Interval
+    >>> S.EmptySet
+    EmptySet
+
+    >>> Interval(1, 2).intersect(S.EmptySet)
+    EmptySet
+
+    See Also
+    ========
+
+    UniversalSet
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Empty_set
+    """
+    is_empty = True
+    is_finite_set = True
+    is_FiniteSet = True
+
+    @property  # type: ignore
+    @deprecated(
+        """
+        The is_EmptySet attribute of Set objects is deprecated.
+        Use 's is S.EmptySet" or 's.is_empty' instead.
+        """,
+        deprecated_since_version="1.5",
+        active_deprecations_target="deprecated-is-emptyset",
+    )
+    def is_EmptySet(self):
+        return True
+
+    @property
+    def _measure(self):
+        return 0
+
+    def _contains(self, other):
+        return false
+
+    def as_relational(self, symbol):
+        return false
+
+    def __len__(self):
+        return 0
+
+    def __iter__(self):
+        return iter([])
+
+    def _eval_powerset(self):
+        return FiniteSet(self)
+
+    @property
+    def _boundary(self):
+        return self
+
+    def _complement(self, other):
+        return other
+
+    def _kind(self):
+        return SetKind()
+
+    def _symmetric_difference(self, other):
+        return other
+
+
+class UniversalSet(Set, metaclass=Singleton):
+    """
+    Represents the set of all things.
+    The universal set is available as a singleton as ``S.UniversalSet``.
+
+    Examples
+    ========
+
+    >>> from sympy import S, Interval
+    >>> S.UniversalSet
+    UniversalSet
+
+    >>> Interval(1, 2).intersect(S.UniversalSet)
+    Interval(1, 2)
+
+    See Also
+    ========
+
+    EmptySet
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Universal_set
+    """
+
+    is_UniversalSet = True
+    is_empty = False
+    is_finite_set = False
+
+    def _complement(self, other):
+        return S.EmptySet
+
+    def _symmetric_difference(self, other):
+        return other
+
+    @property
+    def _measure(self):
+        return S.Infinity
+
+    def _kind(self):
+        return SetKind(UndefinedKind)
+
+    def _contains(self, other):
+        return true
+
+    def as_relational(self, symbol):
+        return true
+
+    @property
+    def _boundary(self):
+        return S.EmptySet
+
+
+class FiniteSet(Set):
+    """
+    Represents a finite set of Sympy expressions.
+
+    Examples
+    ========
+
+    >>> from sympy import FiniteSet, Symbol, Interval, Naturals0
+    >>> FiniteSet(1, 2, 3, 4)
+    {1, 2, 3, 4}
+    >>> 3 in FiniteSet(1, 2, 3, 4)
+    True
+    >>> FiniteSet(1, (1, 2), Symbol('x'))
+    {1, x, (1, 2)}
+    >>> FiniteSet(Interval(1, 2), Naturals0, {1, 2})
+    FiniteSet({1, 2}, Interval(1, 2), Naturals0)
+    >>> members = [1, 2, 3, 4]
+    >>> f = FiniteSet(*members)
+    >>> f
+    {1, 2, 3, 4}
+    >>> f - FiniteSet(2)
+    {1, 3, 4}
+    >>> f + FiniteSet(2, 5)
+    {1, 2, 3, 4, 5}
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Finite_set
+    """
+    is_FiniteSet = True
+    is_iterable = True
+    is_empty = False
+    is_finite_set = True
+
+    def __new__(cls, *args, **kwargs):
+        evaluate = kwargs.get('evaluate', global_parameters.evaluate)
+        if evaluate:
+            args = list(map(sympify, args))
+
+            if len(args) == 0:
+                return S.EmptySet
+        else:
+            args = list(map(sympify, args))
+
+        # keep the form of the first canonical arg
+        dargs = {}
+        for i in reversed(list(ordered(args))):
+            if i.is_Symbol:
+                dargs[i] = i
+            else:
+                try:
+                    dargs[i.as_dummy()] = i
+                except TypeError:
+                    # e.g. i = class without args like `Interval`
+                    dargs[i] = i
+        _args_set = set(dargs.values())
+        args = list(ordered(_args_set, Set._infimum_key))
+        obj = Basic.__new__(cls, *args)
+        obj._args_set = _args_set
+        return obj
+
+
+    def __iter__(self):
+        return iter(self.args)
+
+    def _complement(self, other):
+        if isinstance(other, Interval):
+            # Splitting in sub-intervals is only done for S.Reals;
+            # other cases that need splitting will first pass through
+            # Set._complement().
+            nums, syms = [], []
+            for m in self.args:
+                if m.is_number and m.is_real:
+                    nums.append(m)
+                elif m.is_real == False:
+                    pass  # drop non-reals
+                else:
+                    syms.append(m)  # various symbolic expressions
+            if other == S.Reals and nums != []:
+                nums.sort()
+                intervals = []  # Build up a list of intervals between the elements
+                intervals += [Interval(S.NegativeInfinity, nums[0], True, True)]
+                for a, b in zip(nums[:-1], nums[1:]):
+                    intervals.append(Interval(a, b, True, True))  # both open
+                intervals.append(Interval(nums[-1], S.Infinity, True, True))
+                if syms != []:
+                    return Complement(Union(*intervals, evaluate=False),
+                            FiniteSet(*syms), evaluate=False)
+                else:
+                    return Union(*intervals, evaluate=False)
+            elif nums == []:  # no splitting necessary or possible:
+                if syms:
+                    return Complement(other, FiniteSet(*syms), evaluate=False)
+                else:
+                    return other
+
+        elif isinstance(other, FiniteSet):
+            unk = []
+            for i in self:
+                c = sympify(other.contains(i))
+                if c is not S.true and c is not S.false:
+                    unk.append(i)
+            unk = FiniteSet(*unk)
+            if unk == self:
+                return
+            not_true = []
+            for i in other:
+                c = sympify(self.contains(i))
+                if c is not S.true:
+                    not_true.append(i)
+            return Complement(FiniteSet(*not_true), unk)
+
+        return Set._complement(self, other)
+
+    def _contains(self, other):
+        """
+        Tests whether an element, other, is in the set.
+
+        Explanation
+        ===========
+
+        The actual test is for mathematical equality (as opposed to
+        syntactical equality). In the worst case all elements of the
+        set must be checked.
+
+        Examples
+        ========
+
+        >>> from sympy import FiniteSet
+        >>> 1 in FiniteSet(1, 2)
+        True
+        >>> 5 in FiniteSet(1, 2)
+        False
+
+        """
+        if other in self._args_set:
+            return True
+        else:
+            # evaluate=True is needed to override evaluate=False context;
+            # we need Eq to do the evaluation
+            return fuzzy_or(fuzzy_bool(Eq(e, other, evaluate=True))
+                for e in self.args)
+
+    def _eval_is_subset(self, other):
+        return fuzzy_and(other._contains(e) for e in self.args)
+
+    @property
+    def _boundary(self):
+        return self
+
+    @property
+    def _inf(self):
+        return Min(*self)
+
+    @property
+    def _sup(self):
+        return Max(*self)
+
+    @property
+    def measure(self):
+        return 0
+
+    def _kind(self):
+        if not self.args:
+            return SetKind()
+        elif all(i.kind == self.args[0].kind for i in self.args):
+            return SetKind(self.args[0].kind)
+        else:
+            return SetKind(UndefinedKind)
+
+    def __len__(self):
+        return len(self.args)
+
+    def as_relational(self, symbol):
+        """Rewrite a FiniteSet in terms of equalities and logic operators. """
+        return Or(*[Eq(symbol, elem) for elem in self])
+
+    def compare(self, other):
+        return (hash(self) - hash(other))
+
+    def _eval_evalf(self, prec):
+        dps = prec_to_dps(prec)
+        return FiniteSet(*[elem.evalf(n=dps) for elem in self])
+
+    def _eval_simplify(self, **kwargs):
+        from sympy.simplify import simplify
+        return FiniteSet(*[simplify(elem, **kwargs) for elem in self])
+
+    @property
+    def _sorted_args(self):
+        return self.args
+
+    def _eval_powerset(self):
+        return self.func(*[self.func(*s) for s in subsets(self.args)])
+
+    def _eval_rewrite_as_PowerSet(self, *args, **kwargs):
+        """Rewriting method for a finite set to a power set."""
+        from .powerset import PowerSet
+
+        is2pow = lambda n: bool(n and not n & (n - 1))
+        if not is2pow(len(self)):
+            return None
+
+        fs_test = lambda arg: isinstance(arg, Set) and arg.is_FiniteSet
+        if not all(fs_test(arg) for arg in args):
+            return None
+
+        biggest = max(args, key=len)
+        for arg in subsets(biggest.args):
+            arg_set = FiniteSet(*arg)
+            if arg_set not in args:
+                return None
+        return PowerSet(biggest)
+
+    def __ge__(self, other):
+        if not isinstance(other, Set):
+            raise TypeError("Invalid comparison of set with %s" % func_name(other))
+        return other.is_subset(self)
+
+    def __gt__(self, other):
+        if not isinstance(other, Set):
+            raise TypeError("Invalid comparison of set with %s" % func_name(other))
+        return self.is_proper_superset(other)
+
+    def __le__(self, other):
+        if not isinstance(other, Set):
+            raise TypeError("Invalid comparison of set with %s" % func_name(other))
+        return self.is_subset(other)
+
+    def __lt__(self, other):
+        if not isinstance(other, Set):
+            raise TypeError("Invalid comparison of set with %s" % func_name(other))
+        return self.is_proper_subset(other)
+
+    def __eq__(self, other):
+        if isinstance(other, (set, frozenset)):
+            return self._args_set == other
+        return super().__eq__(other)
+
+    __hash__ : Callable[[Basic], Any] = Basic.__hash__
+
+_sympy_converter[set] = lambda x: FiniteSet(*x)
+_sympy_converter[frozenset] = lambda x: FiniteSet(*x)
+
+
+class SymmetricDifference(Set):
+    """Represents the set of elements which are in either of the
+    sets and not in their intersection.
+
+    Examples
+    ========
+
+    >>> from sympy import SymmetricDifference, FiniteSet
+    >>> SymmetricDifference(FiniteSet(1, 2, 3), FiniteSet(3, 4, 5))
+    {1, 2, 4, 5}
+
+    See Also
+    ========
+
+    Complement, Union
+
+    References
+    ==========
+
+    .. [1] https://en.wikipedia.org/wiki/Symmetric_difference
+    """
+
+    is_SymmetricDifference = True
+
+    def __new__(cls, a, b, evaluate=True):
+        if evaluate:
+            return SymmetricDifference.reduce(a, b)
+
+        return Basic.__new__(cls, a, b)
+
+    @staticmethod
+    def reduce(A, B):
+        result = B._symmetric_difference(A)
+        if result is not None:
+            return result
+        else:
+            return SymmetricDifference(A, B, evaluate=False)
+
+    def as_relational(self, symbol):
+        """Rewrite a symmetric_difference in terms of equalities and
+        logic operators"""
+        A, B = self.args
+
+        A_rel = A.as_relational(symbol)
+        B_rel = B.as_relational(symbol)
+
+        return Xor(A_rel, B_rel)
+
+    @property
+    def is_iterable(self):
+        if all(arg.is_iterable for arg in self.args):
+            return True
+
+    def __iter__(self):
+
+        args = self.args
+        union = roundrobin(*(iter(arg) for arg in args))
+
+        for item in union:
+            count = 0
+            for s in args:
+                if item in s:
+                    count += 1
+
+            if count % 2 == 1:
+                yield item
+
+
+
+class DisjointUnion(Set):
+    """ Represents the disjoint union (also known as the external disjoint union)
+    of a finite number of sets.
+
+    Examples
+    ========
+
+    >>> from sympy import DisjointUnion, FiniteSet, Interval, Union, Symbol
+    >>> A = FiniteSet(1, 2, 3)
+    >>> B = Interval(0, 5)
+    >>> DisjointUnion(A, B)
+    DisjointUnion({1, 2, 3}, Interval(0, 5))
+    >>> DisjointUnion(A, B).rewrite(Union)
+    Union(ProductSet({1, 2, 3}, {0}), ProductSet(Interval(0, 5), {1}))
+    >>> C = FiniteSet(Symbol('x'), Symbol('y'), Symbol('z'))
+    >>> DisjointUnion(C, C)
+    DisjointUnion({x, y, z}, {x, y, z})
+    >>> DisjointUnion(C, C).rewrite(Union)
+    ProductSet({x, y, z}, {0, 1})
+
+    References
+    ==========
+
+    https://en.wikipedia.org/wiki/Disjoint_union
+    """
+
+    def __new__(cls, *sets):
+        dj_collection = []
+        for set_i in sets:
+            if isinstance(set_i, Set):
+                dj_collection.append(set_i)
+            else:
+                raise TypeError("Invalid input: '%s', input args \
+                    to DisjointUnion must be Sets" % set_i)
+        obj = Basic.__new__(cls, *dj_collection)
+        return obj
+
+    @property
+    def sets(self):
+        return self.args
+
+    @property
+    def is_empty(self):
+        return fuzzy_and(s.is_empty for s in self.sets)
+
+    @property
+    def is_finite_set(self):
+        all_finite = fuzzy_and(s.is_finite_set for s in self.sets)
+        return fuzzy_or([self.is_empty, all_finite])
+
+    @property
+    def is_iterable(self):
+        if self.is_empty:
+            return False
+        iter_flag = True
+        for set_i in self.sets:
+            if not set_i.is_empty:
+                iter_flag = iter_flag and set_i.is_iterable
+        return iter_flag
+
+    def _eval_rewrite_as_Union(self, *sets):
+        """
+        Rewrites the disjoint union as the union of (``set`` x {``i``})
+        where ``set`` is the element in ``sets`` at index = ``i``
+        """
+
+        dj_union = S.EmptySet
+        index = 0
+        for set_i in sets:
+            if isinstance(set_i, Set):
+                cross = ProductSet(set_i, FiniteSet(index))
+                dj_union = Union(dj_union, cross)
+                index = index + 1
+        return dj_union
+
+    def _contains(self, element):
+        """
+        ``in`` operator for DisjointUnion
+
+        Examples
+        ========
+
+        >>> from sympy import Interval, DisjointUnion
+        >>> D = DisjointUnion(Interval(0, 1), Interval(0, 2))
+        >>> (0.5, 0) in D
+        True
+        >>> (0.5, 1) in D
+        True
+        >>> (1.5, 0) in D
+        False
+        >>> (1.5, 1) in D
+        True
+
+        Passes operation on to constituent sets
+        """
+        if not isinstance(element, Tuple) or len(element) != 2:
+            return False
+
+        if not element[1].is_Integer:
+            return False
+
+        if element[1] >= len(self.sets) or element[1] < 0:
+            return False
+
+        return element[0] in self.sets[element[1]]
+
+    def _kind(self):
+        if not self.args:
+            return SetKind()
+        elif all(i.kind == self.args[0].kind for i in self.args):
+            return self.args[0].kind
+        else:
+            return SetKind(UndefinedKind)
+
+    def __iter__(self):
+        if self.is_iterable:
+
+            iters = []
+            for i, s in enumerate(self.sets):
+                iters.append(iproduct(s, {Integer(i)}))
+
+            return iter(roundrobin(*iters))
+        else:
+            raise ValueError("'%s' is not iterable." % self)
+
+    def __len__(self):
+        """
+        Returns the length of the disjoint union, i.e., the number of elements in the set.
+
+        Examples
+        ========
+
+        >>> from sympy import FiniteSet, DisjointUnion, EmptySet
+        >>> D1 = DisjointUnion(FiniteSet(1, 2, 3, 4), EmptySet, FiniteSet(3, 4, 5))
+        >>> len(D1)
+        7
+        >>> D2 = DisjointUnion(FiniteSet(3, 5, 7), EmptySet, FiniteSet(3, 5, 7))
+        >>> len(D2)
+        6
+        >>> D3 = DisjointUnion(EmptySet, EmptySet)
+        >>> len(D3)
+        0
+
+        Adds up the lengths of the constituent sets.
+        """
+
+        if self.is_finite_set:
+            size = 0
+            for set in self.sets:
+                size += len(set)
+            return size
+        else:
+            raise ValueError("'%s' is not a finite set." % self)
+
+
+def imageset(*args):
+    r"""
+    Return an image of the set under transformation ``f``.
+
+    Explanation
+    ===========
+
+    If this function cannot compute the image, it returns an
+    unevaluated ImageSet object.
+
+    .. math::
+        \{ f(x) \mid x \in \mathrm{self} \}
+
+    Examples
+    ========
+
+    >>> from sympy import S, Interval, imageset, sin, Lambda
+    >>> from sympy.abc import x
+
+    >>> imageset(x, 2*x, Interval(0, 2))
+    Interval(0, 4)
+
+    >>> imageset(lambda x: 2*x, Interval(0, 2))
+    Interval(0, 4)
+
+    >>> imageset(Lambda(x, sin(x)), Interval(-2, 1))
+    ImageSet(Lambda(x, sin(x)), Interval(-2, 1))
+
+    >>> imageset(sin, Interval(-2, 1))
+    ImageSet(Lambda(x, sin(x)), Interval(-2, 1))
+    >>> imageset(lambda y: x + y, Interval(-2, 1))
+    ImageSet(Lambda(y, x + y), Interval(-2, 1))
+
+    Expressions applied to the set of Integers are simplified
+    to show as few negatives as possible and linear expressions
+    are converted to a canonical form. If this is not desirable
+    then the unevaluated ImageSet should be used.
+
+    >>> imageset(x, -2*x + 5, S.Integers)
+    ImageSet(Lambda(x, 2*x + 1), Integers)
+
+    See Also
+    ========
+
+    sympy.sets.fancysets.ImageSet
+
+    """
+    from .fancysets import ImageSet
+    from .setexpr import set_function
+
+    if len(args) < 2:
+        raise ValueError('imageset expects at least 2 args, got: %s' % len(args))
+
+    if isinstance(args[0], (Symbol, tuple)) and len(args) > 2:
+        f = Lambda(args[0], args[1])
+        set_list = args[2:]
+    else:
+        f = args[0]
+        set_list = args[1:]
+
+    if isinstance(f, Lambda):
+        pass
+    elif callable(f):
+        nargs = getattr(f, 'nargs', {})
+        if nargs:
+            if len(nargs) != 1:
+                raise NotImplementedError(filldedent('''
+                    This function can take more than 1 arg
+                    but the potentially complicated set input
+                    has not been analyzed at this point to
+                    know its dimensions. TODO
+                    '''))
+            N = nargs.args[0]
+            if N == 1:
+                s = 'x'
+            else:
+                s = [Symbol('x%i' % i) for i in range(1, N + 1)]
+        else:
+            s = inspect.signature(f).parameters
+
+        dexpr = _sympify(f(*[Dummy() for i in s]))
+        var = tuple(uniquely_named_symbol(
+            Symbol(i), dexpr) for i in s)
+        f = Lambda(var, f(*var))
+    else:
+        raise TypeError(filldedent('''
+            expecting lambda, Lambda, or FunctionClass,
+            not \'%s\'.''' % func_name(f)))
+
+    if any(not isinstance(s, Set) for s in set_list):
+        name = [func_name(s) for s in set_list]
+        raise ValueError(
+            'arguments after mapping should be sets, not %s' % name)
+
+    if len(set_list) == 1:
+        set = set_list[0]
+        try:
+            # TypeError if arg count != set dimensions
+            r = set_function(f, set)
+            if r is None:
+                raise TypeError
+            if not r:
+                return r
+        except TypeError:
+            r = ImageSet(f, set)
+        if isinstance(r, ImageSet):
+            f, set = r.args
+
+        if f.variables[0] == f.expr:
+            return set
+
+        if isinstance(set, ImageSet):
+            # XXX: Maybe this should just be:
+            # f2 = set.lambda
+            # fun = Lambda(f2.signature, f(*f2.expr))
+            # return imageset(fun, *set.base_sets)
+            if len(set.lamda.variables) == 1 and len(f.variables) == 1:
+                x = set.lamda.variables[0]
+                y = f.variables[0]
+                return imageset(
+                    Lambda(x, f.expr.subs(y, set.lamda.expr)), *set.base_sets)
+
+        if r is not None:
+            return r
+
+    return ImageSet(f, *set_list)
+
+
+def is_function_invertible_in_set(func, setv):
+    """
+    Checks whether function ``func`` is invertible when the domain is
+    restricted to set ``setv``.
+    """
+    # Functions known to always be invertible:
+    if func in (exp, log):
+        return True
+    u = Dummy("u")
+    fdiff = func(u).diff(u)
+    # monotonous functions:
+    # TODO: check subsets (`func` in `setv`)
+    if (fdiff > 0) == True or (fdiff < 0) == True:
+        return True
+    # TODO: support more
+    return None
+
+
+def simplify_union(args):
+    """
+    Simplify a :class:`Union` using known rules.
+
+    Explanation
+    ===========
+
+    We first start with global rules like 'Merge all FiniteSets'
+
+    Then we iterate through all pairs and ask the constituent sets if they
+    can simplify themselves with any other constituent.  This process depends
+    on ``union_sets(a, b)`` functions.
+    """
+    from sympy.sets.handlers.union import union_sets
+
+    # ===== Global Rules =====
+    if not args:
+        return S.EmptySet
+
+    for arg in args:
+        if not isinstance(arg, Set):
+            raise TypeError("Input args to Union must be Sets")
+
+    # Merge all finite sets
+    finite_sets = [x for x in args if x.is_FiniteSet]
+    if len(finite_sets) > 1:
+        a = (x for set in finite_sets for x in set)
+        finite_set = FiniteSet(*a)
+        args = [finite_set] + [x for x in args if not x.is_FiniteSet]
+
+    # ===== Pair-wise Rules =====
+    # Here we depend on rules built into the constituent sets
+    args = set(args)
+    new_args = True
+    while new_args:
+        for s in args:
+            new_args = False
+            for t in args - {s}:
+                new_set = union_sets(s, t)
+                # This returns None if s does not know how to intersect
+                # with t. Returns the newly intersected set otherwise
+                if new_set is not None:
+                    if not isinstance(new_set, set):
+                        new_set = {new_set}
+                    new_args = (args - {s, t}).union(new_set)
+                    break
+            if new_args:
+                args = new_args
+                break
+
+    if len(args) == 1:
+        return args.pop()
+    else:
+        return Union(*args, evaluate=False)
+
+
+def simplify_intersection(args):
+    """
+    Simplify an intersection using known rules.
+
+    Explanation
+    ===========
+
+    We first start with global rules like
+    'if any empty sets return empty set' and 'distribute any unions'
+
+    Then we iterate through all pairs and ask the constituent sets if they
+    can simplify themselves with any other constituent
+    """
+
+    # ===== Global Rules =====
+    if not args:
+        return S.UniversalSet
+
+    for arg in args:
+        if not isinstance(arg, Set):
+            raise TypeError("Input args to Union must be Sets")
+
+    # If any EmptySets return EmptySet
+    if S.EmptySet in args:
+        return S.EmptySet
+
+    # Handle Finite sets
+    rv = Intersection._handle_finite_sets(args)
+
+    if rv is not None:
+        return rv
+
+    # If any of the sets are unions, return a Union of Intersections
+    for s in args:
+        if s.is_Union:
+            other_sets = set(args) - {s}
+            if len(other_sets) > 0:
+                other = Intersection(*other_sets)
+                return Union(*(Intersection(arg, other) for arg in s.args))
+            else:
+                return Union(*s.args)
+
+    for s in args:
+        if s.is_Complement:
+            args.remove(s)
+            other_sets = args + [s.args[0]]
+            return Complement(Intersection(*other_sets), s.args[1])
+
+    from sympy.sets.handlers.intersection import intersection_sets
+
+    # At this stage we are guaranteed not to have any
+    # EmptySets, FiniteSets, or Unions in the intersection
+
+    # ===== Pair-wise Rules =====
+    # Here we depend on rules built into the constituent sets
+    args = set(args)
+    new_args = True
+    while new_args:
+        for s in args:
+            new_args = False
+            for t in args - {s}:
+                new_set = intersection_sets(s, t)
+                # This returns None if s does not know how to intersect
+                # with t. Returns the newly intersected set otherwise
+
+                if new_set is not None:
+                    new_args = (args - {s, t}).union({new_set})
+                    break
+            if new_args:
+                args = new_args
+                break
+
+    if len(args) == 1:
+        return args.pop()
+    else:
+        return Intersection(*args, evaluate=False)
+
+
+def _handle_finite_sets(op, x, y, commutative):
+    # Handle finite sets:
+    fs_args, other = sift([x, y], lambda x: isinstance(x, FiniteSet), binary=True)
+    if len(fs_args) == 2:
+        return FiniteSet(*[op(i, j) for i in fs_args[0] for j in fs_args[1]])
+    elif len(fs_args) == 1:
+        sets = [_apply_operation(op, other[0], i, commutative) for i in fs_args[0]]
+        return Union(*sets)
+    else:
+        return None
+
+
+def _apply_operation(op, x, y, commutative):
+    from .fancysets import ImageSet
+    d = Dummy('d')
+
+    out = _handle_finite_sets(op, x, y, commutative)
+    if out is None:
+        out = op(x, y)
+
+    if out is None and commutative:
+        out = op(y, x)
+    if out is None:
+        _x, _y = symbols("x y")
+        if isinstance(x, Set) and not isinstance(y, Set):
+            out = ImageSet(Lambda(d, op(d, y)), x).doit()
+        elif not isinstance(x, Set) and isinstance(y, Set):
+            out = ImageSet(Lambda(d, op(x, d)), y).doit()
+        else:
+            out = ImageSet(Lambda((_x, _y), op(_x, _y)), x, y)
+    return out
+
+
+def set_add(x, y):
+    from sympy.sets.handlers.add import _set_add
+    return _apply_operation(_set_add, x, y, commutative=True)
+
+
+def set_sub(x, y):
+    from sympy.sets.handlers.add import _set_sub
+    return _apply_operation(_set_sub, x, y, commutative=False)
+
+
+def set_mul(x, y):
+    from sympy.sets.handlers.mul import _set_mul
+    return _apply_operation(_set_mul, x, y, commutative=True)
+
+
+def set_div(x, y):
+    from sympy.sets.handlers.mul import _set_div
+    return _apply_operation(_set_div, x, y, commutative=False)
+
+
+def set_pow(x, y):
+    from sympy.sets.handlers.power import _set_pow
+    return _apply_operation(_set_pow, x, y, commutative=False)
+
+
+def set_function(f, x):
+    from sympy.sets.handlers.functions import _set_function
+    return _set_function(f, x)
+
+
+class SetKind(Kind):
+    """
+    SetKind is kind for all Sets
+
+    Every instance of Set will have kind ``SetKind`` parametrised by the kind
+    of the elements of the ``Set``. The kind of the elements might be
+    ``NumberKind``, or ``TupleKind`` or something else. When not all elements
+    have the same kind then the kind of the elements will be given as
+    ``UndefinedKind``.
+
+    Parameters
+    ==========
+
+    element_kind: Kind (optional)
+        The kind of the elements of the set. In a well defined set all elements
+        will have the same kind. Otherwise the kind should
+        :class:`sympy.core.kind.UndefinedKind`. The ``element_kind`` argument is optional but
+        should only be omitted in the case of ``EmptySet`` whose kind is simply
+        ``SetKind()``
+
+    Examples
+    ========
+
+    >>> from sympy import Interval
+    >>> Interval(1, 2).kind
+    SetKind(NumberKind)
+    >>> Interval(1,2).kind.element_kind
+    NumberKind
+
+    See Also
+    ========
+
+    sympy.core.kind.NumberKind
+    sympy.matrices.common.MatrixKind
+    sympy.core.containers.TupleKind
+    """
+    def __new__(cls, element_kind=None):
+        obj = super().__new__(cls, element_kind)
+        obj.element_kind = element_kind
+        return obj
+
+    def __repr__(self):
+        if not self.element_kind:
+            return "SetKind()"
+        else:
+            return "SetKind(%s)" % self.element_kind

venv/lib/python3.10/site-packages/sympy/sets/tests/test_conditionset.py

@@ -0,0 +1,294 @@
+from sympy.core.expr import unchanged
+from sympy.sets import (ConditionSet, Intersection, FiniteSet,
+    EmptySet, Union, Contains, ImageSet)
+from sympy.sets.sets import SetKind
+from sympy.core.function import (Function, Lambda)
+from sympy.core.mod import Mod
+from sympy.core.kind import NumberKind
+from sympy.core.numbers import (oo, pi)
+from sympy.core.relational import (Eq, Ne)
+from sympy.core.singleton import S
+from sympy.core.symbol import (Symbol, symbols)
+from sympy.functions.elementary.complexes import Abs
+from sympy.functions.elementary.trigonometric import (asin, sin)
+from sympy.logic.boolalg import And
+from sympy.matrices.dense import Matrix
+from sympy.matrices.expressions.matexpr import MatrixSymbol
+from sympy.sets.sets import Interval
+from sympy.testing.pytest import raises, warns_deprecated_sympy
+
+
+w = Symbol('w')
+x = Symbol('x')
+y = Symbol('y')
+z = Symbol('z')
+f = Function('f')
+
+
+def test_CondSet():
+    sin_sols_principal = ConditionSet(x, Eq(sin(x), 0),
+                                      Interval(0, 2*pi, False, True))
+    assert pi in sin_sols_principal
+    assert pi/2 not in sin_sols_principal
+    assert 3*pi not in sin_sols_principal
+    assert oo not in sin_sols_principal
+    assert 5 in ConditionSet(x, x**2 > 4, S.Reals)
+    assert 1 not in ConditionSet(x, x**2 > 4, S.Reals)
+    # in this case, 0 is not part of the base set so
+    # it can't be in any subset selected by the condition
+    assert 0 not in ConditionSet(x, y > 5, Interval(1, 7))
+    # since 'in' requires a true/false, the following raises
+    # an error because the given value provides no information
+    # for the condition to evaluate (since the condition does
+    # not depend on the dummy symbol): the result is `y > 5`.
+    # In this case, ConditionSet is just acting like
+    # Piecewise((Interval(1, 7), y > 5), (S.EmptySet, True)).
+    raises(TypeError, lambda: 6 in ConditionSet(x, y > 5,
+        Interval(1, 7)))
+
+    X = MatrixSymbol('X', 2, 2)
+    matrix_set = ConditionSet(X, Eq(X*Matrix([[1, 1], [1, 1]]), X))
+    Y = Matrix([[0, 0], [0, 0]])
+    assert matrix_set.contains(Y).doit() is S.true
+    Z = Matrix([[1, 2], [3, 4]])
+    assert matrix_set.contains(Z).doit() is S.false
+
+    assert isinstance(ConditionSet(x, x < 1, {x, y}).base_set,
+        FiniteSet)
+    raises(TypeError, lambda: ConditionSet(x, x + 1, {x, y}))
+    raises(TypeError, lambda: ConditionSet(x, x, 1))
+
+    I = S.Integers
+    U = S.UniversalSet
+    C = ConditionSet
+    assert C(x, False, I) is S.EmptySet
+    assert C(x, True, I) is I
+    assert C(x, x < 1, C(x, x < 2, I)
+        ) == C(x, (x < 1) & (x < 2), I)
+    assert C(y, y < 1, C(x, y < 2, I)
+        ) == C(x, (x < 1) & (y < 2), I), C(y, y < 1, C(x, y < 2, I))
+    assert C(y, y < 1, C(x, x < 2, I)
+        ) == C(y, (y < 1) & (y < 2), I)
+    assert C(y, y < 1, C(x, y < x, I)
+        ) == C(x, (x < 1) & (y < x), I)
+    assert unchanged(C, y, x < 1, C(x, y < x, I))
+    assert ConditionSet(x, x < 1).base_set is U
+    # arg checking is not done at instantiation but this
+    # will raise an error when containment is tested
+    assert ConditionSet((x,), x < 1).base_set is U
+
+    c = ConditionSet((x, y), x < y, I**2)
+    assert (1, 2) in c
+    assert (1, pi) not in c
+
+    raises(TypeError, lambda: C(x, x > 1, C((x, y), x > 1, I**2)))
+    # signature mismatch since only 3 args are accepted
+    raises(TypeError, lambda: C((x, y), x + y < 2, U, U))
+
+
+def test_CondSet_intersect():
+    input_conditionset = ConditionSet(x, x**2 > 4, Interval(1, 4, False,
+        False))
+    other_domain = Interval(0, 3, False, False)
+    output_conditionset = ConditionSet(x, x**2 > 4, Interval(
+        1, 3, False, False))
+    assert Intersection(input_conditionset, other_domain
+        ) == output_conditionset
+
+
+def test_issue_9849():
+    assert ConditionSet(x, Eq(x, x), S.Naturals
+        ) is S.Naturals
+    assert ConditionSet(x, Eq(Abs(sin(x)), -1), S.Naturals
+        ) == S.EmptySet
+
+
+def test_simplified_FiniteSet_in_CondSet():
+    assert ConditionSet(x, And(x < 1, x > -3), FiniteSet(0, 1, 2)
+        ) == FiniteSet(0)
+    assert ConditionSet(x, x < 0, FiniteSet(0, 1, 2)) == EmptySet
+    assert ConditionSet(x, And(x < -3), EmptySet) == EmptySet
+    y = Symbol('y')
+    assert (ConditionSet(x, And(x > 0), FiniteSet(-1, 0, 1, y)) ==
+        Union(FiniteSet(1), ConditionSet(x, And(x > 0), FiniteSet(y))))
+    assert (ConditionSet(x, Eq(Mod(x, 3), 1), FiniteSet(1, 4, 2, y)) ==
+        Union(FiniteSet(1, 4), ConditionSet(x, Eq(Mod(x, 3), 1),
+        FiniteSet(y))))
+
+
+def test_free_symbols():
+    assert ConditionSet(x, Eq(y, 0), FiniteSet(z)
+        ).free_symbols == {y, z}
+    assert ConditionSet(x, Eq(x, 0), FiniteSet(z)
+        ).free_symbols == {z}
+    assert ConditionSet(x, Eq(x, 0), FiniteSet(x, z)
+        ).free_symbols == {x, z}
+    assert ConditionSet(x, Eq(x, 0), ImageSet(Lambda(y, y**2),
+        S.Integers)).free_symbols == set()
+
+
+def test_bound_symbols():
+    assert ConditionSet(x, Eq(y, 0), FiniteSet(z)
+        ).bound_symbols == [x]
+    assert ConditionSet(x, Eq(x, 0), FiniteSet(x, y)
+        ).bound_symbols == [x]
+    assert ConditionSet(x, x < 10, ImageSet(Lambda(y, y**2), S.Integers)
+        ).bound_symbols == [x]
+    assert ConditionSet(x, x < 10, ConditionSet(y, y > 1, S.Integers)
+        ).bound_symbols == [x]
+
+
+def test_as_dummy():
+    _0, _1 = symbols('_0 _1')
+    assert ConditionSet(x, x < 1, Interval(y, oo)
+        ).as_dummy() == ConditionSet(_0, _0 < 1, Interval(y, oo))
+    assert ConditionSet(x, x < 1, Interval(x, oo)
+        ).as_dummy() == ConditionSet(_0, _0 < 1, Interval(x, oo))
+    assert ConditionSet(x, x < 1, ImageSet(Lambda(y, y**2), S.Integers)
+        ).as_dummy() == ConditionSet(
+            _0, _0 < 1, ImageSet(Lambda(_0, _0**2), S.Integers))
+    e = ConditionSet((x, y), x <= y, S.Reals**2)
+    assert e.bound_symbols == [x, y]
+    assert e.as_dummy() == ConditionSet((_0, _1), _0 <= _1, S.Reals**2)
+    assert e.as_dummy() == ConditionSet((y, x), y <= x, S.Reals**2
+        ).as_dummy()
+
+
+def test_subs_CondSet():
+    s = FiniteSet(z, y)
+    c = ConditionSet(x, x < 2, s)
+    assert c.subs(x, y) == c
+    assert c.subs(z, y) == ConditionSet(x, x < 2, FiniteSet(y))
+    assert c.xreplace({x: y}) == ConditionSet(y, y < 2, s)
+
+    assert ConditionSet(x, x < y, s
+        ).subs(y, w) == ConditionSet(x, x < w, s.subs(y, w))
+    # if the user uses assumptions that cause the condition
+    # to evaluate, that can't be helped from SymPy's end
+    n = Symbol('n', negative=True)
+    assert ConditionSet(n, 0 < n, S.Integers) is S.EmptySet
+    p = Symbol('p', positive=True)
+    assert ConditionSet(n, n < y, S.Integers
+        ).subs(n, x) == ConditionSet(n, n < y, S.Integers)
+    raises(ValueError, lambda: ConditionSet(
+        x + 1, x < 1, S.Integers))
+    assert ConditionSet(
+        p, n < x, Interval(-5, 5)).subs(x, p) == Interval(-5, 5), ConditionSet(
+        p, n < x, Interval(-5, 5)).subs(x, p)
+    assert ConditionSet(
+        n, n < x, Interval(-oo, 0)).subs(x, p
+        ) == Interval(-oo, 0)
+
+    assert ConditionSet(f(x), f(x) < 1, {w, z}
+        ).subs(f(x), y) == ConditionSet(f(x), f(x) < 1, {w, z})
+
+    # issue 17341
+    k = Symbol('k')
+    img1 = ImageSet(Lambda(k, 2*k*pi + asin(y)), S.Integers)
+    img2 = ImageSet(Lambda(k, 2*k*pi + asin(S.One/3)), S.Integers)
+    assert ConditionSet(x, Contains(
+        y, Interval(-1,1)), img1).subs(y, S.One/3).dummy_eq(img2)
+
+    assert (0, 1) in ConditionSet((x, y), x + y < 3, S.Integers**2)
+
+    raises(TypeError, lambda: ConditionSet(n, n < -10, Interval(0, 10)))
+
+
+def test_subs_CondSet_tebr():
+    with warns_deprecated_sympy():
+        assert ConditionSet((x, y), {x + 1, x + y}, S.Reals**2) == \
+            ConditionSet((x, y), Eq(x + 1, 0) & Eq(x + y, 0), S.Reals**2)
+
+
+def test_dummy_eq():
+    C = ConditionSet
+    I = S.Integers
+    c = C(x, x < 1, I)
+    assert c.dummy_eq(C(y, y < 1, I))
+    assert c.dummy_eq(1) == False
+    assert c.dummy_eq(C(x, x < 1, S.Reals)) == False
+
+    c1 = ConditionSet((x, y), Eq(x + 1, 0) & Eq(x + y, 0), S.Reals**2)
+    c2 = ConditionSet((x, y), Eq(x + 1, 0) & Eq(x + y, 0), S.Reals**2)
+    c3 = ConditionSet((x, y), Eq(x + 1, 0) & Eq(x + y, 0), S.Complexes**2)
+    assert c1.dummy_eq(c2)
+    assert c1.dummy_eq(c3) is False
+    assert c.dummy_eq(c1) is False
+    assert c1.dummy_eq(c) is False
+
+    # issue 19496
+    m = Symbol('m')
+    n = Symbol('n')
+    a = Symbol('a')
+    d1 = ImageSet(Lambda(m, m*pi), S.Integers)
+    d2 = ImageSet(Lambda(n, n*pi), S.Integers)
+    c1 = ConditionSet(x, Ne(a, 0), d1)
+    c2 = ConditionSet(x, Ne(a, 0), d2)
+    assert c1.dummy_eq(c2)
+
+
+def test_contains():
+    assert 6 in ConditionSet(x, x > 5, Interval(1, 7))
+    assert (8 in ConditionSet(x, y > 5, Interval(1, 7))) is False
+    # `in` should give True or False; in this case there is not
+    # enough information for that result
+    raises(TypeError,
+        lambda: 6 in ConditionSet(x, y > 5, Interval(1, 7)))
+    # here, there is enough information but the comparison is
+    # not defined
+    raises(TypeError, lambda: 0 in ConditionSet(x, 1/x >= 0, S.Reals))
+    assert ConditionSet(x, y > 5, Interval(1, 7)
+        ).contains(6) == (y > 5)
+    assert ConditionSet(x, y > 5, Interval(1, 7)
+        ).contains(8) is S.false
+    assert ConditionSet(x, y > 5, Interval(1, 7)
+        ).contains(w) == And(Contains(w, Interval(1, 7)), y > 5)
+    # This returns an unevaluated Contains object
+    # because 1/0 should not be defined for 1 and 0 in the context of
+    # reals.
+    assert ConditionSet(x, 1/x >= 0, S.Reals).contains(0) == \
+        Contains(0, ConditionSet(x, 1/x >= 0, S.Reals), evaluate=False)
+    c = ConditionSet((x, y), x + y > 1, S.Integers**2)
+    assert not c.contains(1)
+    assert c.contains((2, 1))
+    assert not c.contains((0, 1))
+    c = ConditionSet((w, (x, y)), w + x + y > 1, S.Integers*S.Integers**2)
+    assert not c.contains(1)
+    assert not c.contains((1, 2))
+    assert not c.contains(((1, 2), 3))
+    assert not c.contains(((1, 2), (3, 4)))
+    assert c.contains((1, (3, 4)))
+
+
+def test_as_relational():
+    assert ConditionSet((x, y), x > 1, S.Integers**2).as_relational((x, y)
+        ) == (x > 1) & Contains((x, y), S.Integers**2)
+    assert ConditionSet(x, x > 1, S.Integers).as_relational(x
+        ) == Contains(x, S.Integers) & (x > 1)
+
+
+def test_flatten():
+    """Tests whether there is basic denesting functionality"""
+    inner = ConditionSet(x, sin(x) + x > 0)
+    outer = ConditionSet(x, Contains(x, inner), S.Reals)
+    assert outer == ConditionSet(x, sin(x) + x > 0, S.Reals)
+
+    inner = ConditionSet(y, sin(y) + y > 0)
+    outer = ConditionSet(x, Contains(y, inner), S.Reals)
+    assert outer != ConditionSet(x, sin(x) + x > 0, S.Reals)
+
+    inner = ConditionSet(x, sin(x) + x > 0).intersect(Interval(-1, 1))
+    outer = ConditionSet(x, Contains(x, inner), S.Reals)
+    assert outer == ConditionSet(x, sin(x) + x > 0, Interval(-1, 1))
+
+
+def test_duplicate():
+    from sympy.core.function import BadSignatureError
+    # test coverage for line 95 in conditionset.py, check for duplicates in symbols
+    dup = symbols('a,a')
+    raises(BadSignatureError, lambda: ConditionSet(dup, x < 0))
+
+
+def test_SetKind_ConditionSet():
+    assert ConditionSet(x, Eq(sin(x), 0), Interval(0, 2*pi)).kind is SetKind(NumberKind)
+    assert ConditionSet(x, x < 0).kind is SetKind(NumberKind)

venv/lib/python3.10/site-packages/sympy/sets/tests/test_contains.py

@@ -0,0 +1,50 @@
+from sympy.core.expr import unchanged
+from sympy.core.numbers import oo
+from sympy.core.relational import Eq
+from sympy.core.singleton import S
+from sympy.core.symbol import Symbol
+from sympy.sets.contains import Contains
+from sympy.sets.sets import (FiniteSet, Interval)
+from sympy.testing.pytest import raises
+
+def test_contains_basic():
+    raises(TypeError, lambda: Contains(S.Integers, 1))
+    assert Contains(2, S.Integers) is S.true
+    assert Contains(-2, S.Naturals) is S.false
+
+    i = Symbol('i', integer=True)
+    assert Contains(i, S.Naturals) == Contains(i, S.Naturals, evaluate=False)
+
+
+def test_issue_6194():
+    x = Symbol('x')
+    assert unchanged(Contains, x, Interval(0, 1))
+    assert Interval(0, 1).contains(x) == (S.Zero <= x) & (x <= 1)
+    assert Contains(x, FiniteSet(0)) != S.false
+    assert Contains(x, Interval(1, 1)) != S.false
+    assert Contains(x, S.Integers) != S.false
+
+
+def test_issue_10326():
+    assert Contains(oo, Interval(-oo, oo)) == False
+    assert Contains(-oo, Interval(-oo, oo)) == False
+
+
+def test_binary_symbols():
+    x = Symbol('x')
+    y = Symbol('y')
+    z = Symbol('z')
+    assert Contains(x, FiniteSet(y, Eq(z, True))
+        ).binary_symbols == {y, z}
+
+
+def test_as_set():
+    x = Symbol('x')
+    y = Symbol('y')
+    assert Contains(x, FiniteSet(y)).as_set() == FiniteSet(y)
+    assert Contains(x, S.Integers).as_set() == S.Integers
+    assert Contains(x, S.Reals).as_set() == S.Reals
+
+def test_type_error():
+    # Pass in a parameter not of type "set"
+    raises(TypeError, lambda: Contains(2, None))

venv/lib/python3.10/site-packages/sympy/sets/tests/test_fancysets.py

@@ -0,0 +1,1306 @@
+
+from sympy.core.expr import unchanged
+from sympy.sets.contains import Contains
+from sympy.sets.fancysets import (ImageSet, Range, normalize_theta_set,
+                                  ComplexRegion)
+from sympy.sets.sets import (FiniteSet, Interval, Union, imageset,
+                             Intersection, ProductSet, SetKind)
+from sympy.sets.conditionset import ConditionSet
+from sympy.simplify.simplify import simplify
+from sympy.core.basic import Basic
+from sympy.core.containers import Tuple, TupleKind
+from sympy.core.function import Lambda
+from sympy.core.kind import NumberKind
+from sympy.core.numbers import (I, Rational, oo, pi)
+from sympy.core.relational import Eq
+from sympy.core.singleton import S
+from sympy.core.symbol import (Dummy, Symbol, symbols)
+from sympy.functions.elementary.complexes import Abs
+from sympy.functions.elementary.exponential import (exp, log)
+from sympy.functions.elementary.integers import floor
+from sympy.functions.elementary.miscellaneous import sqrt
+from sympy.functions.elementary.trigonometric import (cos, sin, tan)
+from sympy.logic.boolalg import And
+from sympy.matrices.dense import eye
+from sympy.testing.pytest import XFAIL, raises
+from sympy.abc import x, y, t, z
+from sympy.core.mod import Mod
+
+import itertools
+
+
+def test_naturals():
+    N = S.Naturals
+    assert 5 in N
+    assert -5 not in N
+    assert 5.5 not in N
+    ni = iter(N)
+    a, b, c, d = next(ni), next(ni), next(ni), next(ni)
+    assert (a, b, c, d) == (1, 2, 3, 4)
+    assert isinstance(a, Basic)
+
+    assert N.intersect(Interval(-5, 5)) == Range(1, 6)
+    assert N.intersect(Interval(-5, 5, True, True)) == Range(1, 5)
+
+    assert N.boundary == N
+    assert N.is_open == False
+    assert N.is_closed == True
+
+    assert N.inf == 1
+    assert N.sup is oo
+    assert not N.contains(oo)
+    for s in (S.Naturals0, S.Naturals):
+        assert s.intersection(S.Reals) is s
+        assert s.is_subset(S.Reals)
+
+    assert N.as_relational(x) == And(Eq(floor(x), x), x >= 1, x < oo)
+
+
+def test_naturals0():
+    N = S.Naturals0
+    assert 0 in N
+    assert -1 not in N
+    assert next(iter(N)) == 0
+    assert not N.contains(oo)
+    assert N.contains(sin(x)) == Contains(sin(x), N)
+
+
+def test_integers():
+    Z = S.Integers
+    assert 5 in Z
+    assert -5 in Z
+    assert 5.5 not in Z
+    assert not Z.contains(oo)
+    assert not Z.contains(-oo)
+
+    zi = iter(Z)
+    a, b, c, d = next(zi), next(zi), next(zi), next(zi)
+    assert (a, b, c, d) == (0, 1, -1, 2)
+    assert isinstance(a, Basic)
+
+    assert Z.intersect(Interval(-5, 5)) == Range(-5, 6)
+    assert Z.intersect(Interval(-5, 5, True, True)) == Range(-4, 5)
+    assert Z.intersect(Interval(5, S.Infinity)) == Range(5, S.Infinity)
+    assert Z.intersect(Interval.Lopen(5, S.Infinity)) == Range(6, S.Infinity)
+
+    assert Z.inf is -oo
+    assert Z.sup is oo
+
+    assert Z.boundary == Z
+    assert Z.is_open == False
+    assert Z.is_closed == True
+
+    assert Z.as_relational(x) == And(Eq(floor(x), x), -oo < x, x < oo)
+
+
+def test_ImageSet():
+    raises(ValueError, lambda: ImageSet(x, S.Integers))
+    assert ImageSet(Lambda(x, 1), S.Integers) == FiniteSet(1)
+    assert ImageSet(Lambda(x, y), S.Integers) == {y}
+    assert ImageSet(Lambda(x, 1), S.EmptySet) == S.EmptySet
+    empty = Intersection(FiniteSet(log(2)/pi), S.Integers)
+    assert unchanged(ImageSet, Lambda(x, 1), empty)  # issue #17471
+    squares = ImageSet(Lambda(x, x**2), S.Naturals)
+    assert 4 in squares
+    assert 5 not in squares
+    assert FiniteSet(*range(10)).intersect(squares) == FiniteSet(1, 4, 9)
+
+    assert 16 not in squares.intersect(Interval(0, 10))
+
+    si = iter(squares)
+    a, b, c, d = next(si), next(si), next(si), next(si)
+    assert (a, b, c, d) == (1, 4, 9, 16)
+
+    harmonics = ImageSet(Lambda(x, 1/x), S.Naturals)
+    assert Rational(1, 5) in harmonics
+    assert Rational(.25) in harmonics
+    assert 0.25 not in harmonics
+    assert Rational(.3) not in harmonics
+    assert (1, 2) not in harmonics
+
+    assert harmonics.is_iterable
+
+    assert imageset(x, -x, Interval(0, 1)) == Interval(-1, 0)
+
+    assert ImageSet(Lambda(x, x**2), Interval(0, 2)).doit() == Interval(0, 4)
+    assert ImageSet(Lambda((x, y), 2*x), {4}, {3}).doit() == FiniteSet(8)
+    assert (ImageSet(Lambda((x, y), x+y), {1, 2, 3}, {10, 20, 30}).doit() ==
+                FiniteSet(11, 12, 13, 21, 22, 23, 31, 32, 33))
+
+    c = Interval(1, 3) * Interval(1, 3)
+    assert Tuple(2, 6) in ImageSet(Lambda(((x, y),), (x, 2*y)), c)
+    assert Tuple(2, S.Half) in ImageSet(Lambda(((x, y),), (x, 1/y)), c)
+    assert Tuple(2, -2) not in ImageSet(Lambda(((x, y),), (x, y**2)), c)
+    assert Tuple(2, -2) in ImageSet(Lambda(((x, y),), (x, -2)), c)
+    c3 = ProductSet(Interval(3, 7), Interval(8, 11), Interval(5, 9))
+    assert Tuple(8, 3, 9) in ImageSet(Lambda(((t, y, x),), (y, t, x)), c3)
+    assert Tuple(Rational(1, 8), 3, 9) in ImageSet(Lambda(((t, y, x),), (1/y, t, x)), c3)
+    assert 2/pi not in ImageSet(Lambda(((x, y),), 2/x), c)
+    assert 2/S(100) not in ImageSet(Lambda(((x, y),), 2/x), c)
+    assert Rational(2, 3) in ImageSet(Lambda(((x, y),), 2/x), c)
+
+    S1 = imageset(lambda x, y: x + y, S.Integers, S.Naturals)
+    assert S1.base_pset == ProductSet(S.Integers, S.Naturals)
+    assert S1.base_sets == (S.Integers, S.Naturals)
+
+    # Passing a set instead of a FiniteSet shouldn't raise
+    assert unchanged(ImageSet, Lambda(x, x**2), {1, 2, 3})
+
+    S2 = ImageSet(Lambda(((x, y),), x+y), {(1, 2), (3, 4)})
+    assert 3 in S2.doit()
+    # FIXME: This doesn't yet work:
+    #assert 3 in S2
+    assert S2._contains(3) is None
+
+    raises(TypeError, lambda: ImageSet(Lambda(x, x**2), 1))
+
+
+def test_image_is_ImageSet():
+    assert isinstance(imageset(x, sqrt(sin(x)), Range(5)), ImageSet)
+
+
+def test_halfcircle():
+    r, th = symbols('r, theta', real=True)
+    L = Lambda(((r, th),), (r*cos(th), r*sin(th)))
+    halfcircle = ImageSet(L, Interval(0, 1)*Interval(0, pi))
+
+    assert (1, 0) in halfcircle
+    assert (0, -1) not in halfcircle
+    assert (0, 0) in halfcircle
+    assert halfcircle._contains((r, 0)) is None
+    # This one doesn't work:
+    #assert (r, 2*pi) not in halfcircle
+
+    assert not halfcircle.is_iterable
+
+
+def test_ImageSet_iterator_not_injective():
+    L = Lambda(x, x - x % 2)  # produces 0, 2, 2, 4, 4, 6, 6, ...
+    evens = ImageSet(L, S.Naturals)
+    i = iter(evens)
+    # No repeats here
+    assert (next(i), next(i), next(i), next(i)) == (0, 2, 4, 6)
+
+
+def test_inf_Range_len():
+    raises(ValueError, lambda: len(Range(0, oo, 2)))
+    assert Range(0, oo, 2).size is S.Infinity
+    assert Range(0, -oo, -2).size is S.Infinity
+    assert Range(oo, 0, -2).size is S.Infinity
+    assert Range(-oo, 0, 2).size is S.Infinity
+
+
+def test_Range_set():
+    empty = Range(0)
+
+    assert Range(5) == Range(0, 5) == Range(0, 5, 1)
+
+    r = Range(10, 20, 2)
+    assert 12 in r
+    assert 8 not in r
+    assert 11 not in r
+    assert 30 not in r
+
+    assert list(Range(0, 5)) == list(range(5))
+    assert list(Range(5, 0, -1)) == list(range(5, 0, -1))
+
+
+    assert Range(5, 15).sup == 14
+    assert Range(5, 15).inf == 5
+    assert Range(15, 5, -1).sup == 15
+    assert Range(15, 5, -1).inf == 6
+    assert Range(10, 67, 10).sup == 60
+    assert Range(60, 7, -10).inf == 10
+
+    assert len(Range(10, 38, 10)) == 3
+
+    assert Range(0, 0, 5) == empty
+    assert Range(oo, oo, 1) == empty
+    assert Range(oo, 1, 1) == empty
+    assert Range(-oo, 1, -1) == empty
+    assert Range(1, oo, -1) == empty
+    assert Range(1, -oo, 1) == empty
+    assert Range(1, -4, oo) == empty
+    ip = symbols('ip', positive=True)
+    assert Range(0, ip, -1) == empty
+    assert Range(0, -ip, 1) == empty
+    assert Range(1, -4, -oo) == Range(1, 2)
+    assert Range(1, 4, oo) == Range(1, 2)
+    assert Range(-oo, oo).size == oo
+    assert Range(oo, -oo, -1).size == oo
+    raises(ValueError, lambda: Range(-oo, oo, 2))
+    raises(ValueError, lambda: Range(x, pi, y))
+    raises(ValueError, lambda: Range(x, y, 0))
+
+    assert 5 in Range(0, oo, 5)
+    assert -5 in Range(-oo, 0, 5)
+    assert oo not in Range(0, oo)
+    ni = symbols('ni', integer=False)
+    assert ni not in Range(oo)
+    u = symbols('u', integer=None)
+    assert Range(oo).contains(u) is not False
+    inf = symbols('inf', infinite=True)
+    assert inf not in Range(-oo, oo)
+    raises(ValueError, lambda: Range(0, oo, 2)[-1])
+    raises(ValueError, lambda: Range(0, -oo, -2)[-1])
+    assert Range(-oo, 1, 1)[-1] is S.Zero
+    assert Range(oo, 1, -1)[-1] == 2
+    assert inf not in Range(oo)
+    assert Range(1, 10, 1)[-1] == 9
+    assert all(i.is_Integer for i in Range(0, -1, 1))
+    it = iter(Range(-oo, 0, 2))
+    raises(TypeError, lambda: next(it))
+
+    assert empty.intersect(S.Integers) == empty
+    assert Range(-1, 10, 1).intersect(S.Complexes) == Range(-1, 10, 1)
+    assert Range(-1, 10, 1).intersect(S.Reals) == Range(-1, 10, 1)
+    assert Range(-1, 10, 1).intersect(S.Rationals) == Range(-1, 10, 1)
+    assert Range(-1, 10, 1).intersect(S.Integers) == Range(-1, 10, 1)
+    assert Range(-1, 10, 1).intersect(S.Naturals) == Range(1, 10, 1)
+    assert Range(-1, 10, 1).intersect(S.Naturals0) == Range(0, 10, 1)
+
+    # test slicing
+    assert Range(1, 10, 1)[5] == 6
+    assert Range(1, 12, 2)[5] == 11
+    assert Range(1, 10, 1)[-1] == 9
+    assert Range(1, 10, 3)[-1] == 7
+    raises(ValueError, lambda: Range(oo,0,-1)[1:3:0])
+    raises(ValueError, lambda: Range(oo,0,-1)[:1])
+    raises(ValueError, lambda: Range(1, oo)[-2])
+    raises(ValueError, lambda: Range(-oo, 1)[2])
+    raises(IndexError, lambda: Range(10)[-20])
+    raises(IndexError, lambda: Range(10)[20])
+    raises(ValueError, lambda: Range(2, -oo, -2)[2:2:0])
+    assert Range(2, -oo, -2)[2:2:2] == empty
+    assert Range(2, -oo, -2)[:2:2] == Range(2, -2, -4)
+    raises(ValueError, lambda: Range(-oo, 4, 2)[:2:2])
+    assert Range(-oo, 4, 2)[::-2] == Range(2, -oo, -4)
+    raises(ValueError, lambda: Range(-oo, 4, 2)[::2])
+    assert Range(oo, 2, -2)[::] == Range(oo, 2, -2)
+    assert Range(-oo, 4, 2)[:-2:-2] == Range(2, 0, -4)
+    assert Range(-oo, 4, 2)[:-2:2] == Range(-oo, 0, 4)
+    raises(ValueError, lambda: Range(-oo, 4, 2)[:0:-2])
+    raises(ValueError, lambda: Range(-oo, 4, 2)[:2:-2])
+    assert Range(-oo, 4, 2)[-2::-2] == Range(0, -oo, -4)
+    raises(ValueError, lambda: Range(-oo, 4, 2)[-2:0:-2])
+    raises(ValueError, lambda: Range(-oo, 4, 2)[0::2])
+    assert Range(oo, 2, -2)[0::] == Range(oo, 2, -2)
+    raises(ValueError, lambda: Range(-oo, 4, 2)[0:-2:2])
+    assert Range(oo, 2, -2)[0:-2:] == Range(oo, 6, -2)
+    raises(ValueError, lambda: Range(oo, 2, -2)[0:2:])
+    raises(ValueError, lambda: Range(-oo, 4, 2)[2::-1])
+    assert Range(-oo, 4, 2)[-2::2] == Range(0, 4, 4)
+    assert Range(oo, 0, -2)[-10:0:2] == empty
+    raises(ValueError, lambda: Range(oo, 0, -2)[0])
+    raises(ValueError, lambda: Range(oo, 0, -2)[-10:10:2])
+    raises(ValueError, lambda: Range(oo, 0, -2)[0::-2])
+    assert Range(oo, 0, -2)[0:-4:-2] == empty
+    assert Range(oo, 0, -2)[:0:2] == empty
+    raises(ValueError, lambda: Range(oo, 0, -2)[:1:-1])
+
+    # test empty Range
+    assert Range(x, x, y) == empty
+    assert empty.reversed == empty
+    assert 0 not in empty
+    assert list(empty) == []
+    assert len(empty) == 0
+    assert empty.size is S.Zero
+    assert empty.intersect(FiniteSet(0)) is S.EmptySet
+    assert bool(empty) is False
+    raises(IndexError, lambda: empty[0])
+    assert empty[:0] == empty
+    raises(NotImplementedError, lambda: empty.inf)
+    raises(NotImplementedError, lambda: empty.sup)
+    assert empty.as_relational(x) is S.false
+
+    AB = [None] + list(range(12))
+    for R in [
+            Range(1, 10),
+            Range(1, 10, 2),
+        ]:
+        r = list(R)
+        for a, b, c in itertools.product(AB, AB, [-3, -1, None, 1, 3]):
+            for reverse in range(2):
+                r = list(reversed(r))
+                R = R.reversed
+                result = list(R[a:b:c])
+                ans = r[a:b:c]
+                txt = ('\n%s[%s:%s:%s] = %s -> %s' % (
+                R, a, b, c, result, ans))
+                check = ans == result
+                assert check, txt
+
+    assert Range(1, 10, 1).boundary == Range(1, 10, 1)
+
+    for r in (Range(1, 10, 2), Range(1, oo, 2)):
+        rev = r.reversed
+        assert r.inf == rev.inf and r.sup == rev.sup
+        assert r.step == -rev.step
+
+    builtin_range = range
+
+    raises(TypeError, lambda: Range(builtin_range(1)))
+    assert S(builtin_range(10)) == Range(10)
+    assert S(builtin_range(1000000000000)) == Range(1000000000000)
+
+    # test Range.as_relational
+    assert Range(1, 4).as_relational(x) == (x >= 1) & (x <= 3)  & Eq(Mod(x, 1), 0)
+    assert Range(oo, 1, -2).as_relational(x) == (x >= 3) & (x < oo)  & Eq(Mod(x + 1, -2), 0)
+
+
+def test_Range_symbolic():
+    # symbolic Range
+    xr = Range(x, x + 4, 5)
+    sr = Range(x, y, t)
+    i = Symbol('i', integer=True)
+    ip = Symbol('i', integer=True, positive=True)
+    ipr = Range(ip)
+    inr = Range(0, -ip, -1)
+    ir = Range(i, i + 19, 2)
+    ir2 = Range(i, i*8, 3*i)
+    i = Symbol('i', integer=True)
+    inf = symbols('inf', infinite=True)
+    raises(ValueError, lambda: Range(inf))
+    raises(ValueError, lambda: Range(inf, 0, -1))
+    raises(ValueError, lambda: Range(inf, inf, 1))
+    raises(ValueError, lambda: Range(1, 1, inf))
+    # args
+    assert xr.args == (x, x + 5, 5)
+    assert sr.args == (x, y, t)
+    assert ir.args == (i, i + 20, 2)
+    assert ir2.args == (i, 10*i, 3*i)
+    # reversed
+    raises(ValueError, lambda: xr.reversed)
+    raises(ValueError, lambda: sr.reversed)
+    assert ipr.reversed.args == (ip - 1, -1, -1)
+    assert inr.reversed.args == (-ip + 1, 1, 1)
+    assert ir.reversed.args == (i + 18, i - 2, -2)
+    assert ir2.reversed.args == (7*i, -2*i, -3*i)
+    # contains
+    assert inf not in sr
+    assert inf not in ir
+    assert 0 in ipr
+    assert 0 in inr
+    raises(TypeError, lambda: 1 in ipr)
+    raises(TypeError, lambda: -1 in inr)
+    assert .1 not in sr
+    assert .1 not in ir
+    assert i + 1 not in ir
+    assert i + 2 in ir
+    raises(TypeError, lambda: x in xr)  # XXX is this what contains is supposed to do?
+    raises(TypeError, lambda: 1 in sr)  # XXX is this what contains is supposed to do?
+    # iter
+    raises(ValueError, lambda: next(iter(xr)))
+    raises(ValueError, lambda: next(iter(sr)))
+    assert next(iter(ir)) == i
+    assert next(iter(ir2)) == i
+    assert sr.intersect(S.Integers) == sr
+    assert sr.intersect(FiniteSet(x)) == Intersection({x}, sr)
+    raises(ValueError, lambda: sr[:2])
+    raises(ValueError, lambda: xr[0])
+    raises(ValueError, lambda: sr[0])
+    # len
+    assert len(ir) == ir.size == 10
+    assert len(ir2) == ir2.size == 3
+    raises(ValueError, lambda: len(xr))
+    raises(ValueError, lambda: xr.size)
+    raises(ValueError, lambda: len(sr))
+    raises(ValueError, lambda: sr.size)
+    # bool
+    assert bool(Range(0)) == False
+    assert bool(xr)
+    assert bool(ir)
+    assert bool(ipr)
+    assert bool(inr)
+    raises(ValueError, lambda: bool(sr))
+    raises(ValueError, lambda: bool(ir2))
+    # inf
+    raises(ValueError, lambda: xr.inf)
+    raises(ValueError, lambda: sr.inf)
+    assert ipr.inf == 0
+    assert inr.inf == -ip + 1
+    assert ir.inf == i
+    raises(ValueError, lambda: ir2.inf)
+    # sup
+    raises(ValueError, lambda: xr.sup)
+    raises(ValueError, lambda: sr.sup)
+    assert ipr.sup == ip - 1
+    assert inr.sup == 0
+    assert ir.inf == i
+    raises(ValueError, lambda: ir2.sup)
+    # getitem
+    raises(ValueError, lambda: xr[0])
+    raises(ValueError, lambda: sr[0])
+    raises(ValueError, lambda: sr[-1])
+    raises(ValueError, lambda: sr[:2])
+    assert ir[:2] == Range(i, i + 4, 2)
+    assert ir[0] == i
+    assert ir[-2] == i + 16
+    assert ir[-1] == i + 18
+    assert ir2[:2] == Range(i, 7*i, 3*i)
+    assert ir2[0] == i
+    assert ir2[-2] == 4*i
+    assert ir2[-1] == 7*i
+    raises(ValueError, lambda: Range(i)[-1])
+    assert ipr[0] == ipr.inf == 0
+    assert ipr[-1] == ipr.sup == ip - 1
+    assert inr[0] == inr.sup == 0
+    assert inr[-1] == inr.inf == -ip + 1
+    raises(ValueError, lambda: ipr[-2])
+    assert ir.inf == i
+    assert ir.sup == i + 18
+    raises(ValueError, lambda: Range(i).inf)
+    # as_relational
+    assert ir.as_relational(x) == ((x >= i) & (x <= i + 18) &
+        Eq(Mod(-i + x, 2), 0))
+    assert ir2.as_relational(x) == Eq(
+        Mod(-i + x, 3*i), 0) & (((x >= i) & (x <= 7*i) & (3*i >= 1)) |
+        ((x <= i) & (x >= 7*i) & (3*i <= -1)))
+    assert Range(i, i + 1).as_relational(x) == Eq(x, i)
+    assert sr.as_relational(z) == Eq(
+        Mod(t, 1), 0) & Eq(Mod(x, 1), 0) & Eq(Mod(-x + z, t), 0
+        ) & (((z >= x) & (z <= -t + y) & (t >= 1)) |
+        ((z <= x) & (z >= -t + y) & (t <= -1)))
+    assert xr.as_relational(z) == Eq(z, x) & Eq(Mod(x, 1), 0)
+    # symbols can clash if user wants (but it must be integer)
+    assert xr.as_relational(x) == Eq(Mod(x, 1), 0)
+    # contains() for symbolic values (issue #18146)
+    e = Symbol('e', integer=True, even=True)
+    o = Symbol('o', integer=True, odd=True)
+    assert Range(5).contains(i) == And(i >= 0, i <= 4)
+    assert Range(1).contains(i) == Eq(i, 0)
+    assert Range(-oo, 5, 1).contains(i) == (i <= 4)
+    assert Range(-oo, oo).contains(i) == True
+    assert Range(0, 8, 2).contains(i) == Contains(i, Range(0, 8, 2))
+    assert Range(0, 8, 2).contains(e) == And(e >= 0, e <= 6)
+    assert Range(0, 8, 2).contains(2*i) == And(2*i >= 0, 2*i <= 6)
+    assert Range(0, 8, 2).contains(o) == False
+    assert Range(1, 9, 2).contains(e) == False
+    assert Range(1, 9, 2).contains(o) == And(o >= 1, o <= 7)
+    assert Range(8, 0, -2).contains(o) == False
+    assert Range(9, 1, -2).contains(o) == And(o >= 3, o <= 9)
+    assert Range(-oo, 8, 2).contains(i) == Contains(i, Range(-oo, 8, 2))
+
+
+def test_range_range_intersection():
+    for a, b, r in [
+            (Range(0), Range(1), S.EmptySet),
+            (Range(3), Range(4, oo), S.EmptySet),
+            (Range(3), Range(-3, -1), S.EmptySet),
+            (Range(1, 3), Range(0, 3), Range(1, 3)),
+            (Range(1, 3), Range(1, 4), Range(1, 3)),
+            (Range(1, oo, 2), Range(2, oo, 2), S.EmptySet),
+            (Range(0, oo, 2), Range(oo), Range(0, oo, 2)),
+            (Range(0, oo, 2), Range(100), Range(0, 100, 2)),
+            (Range(2, oo, 2), Range(oo), Range(2, oo, 2)),
+            (Range(0, oo, 2), Range(5, 6), S.EmptySet),
+            (Range(2, 80, 1), Range(55, 71, 4), Range(55, 71, 4)),
+            (Range(0, 6, 3), Range(-oo, 5, 3), S.EmptySet),
+            (Range(0, oo, 2), Range(5, oo, 3), Range(8, oo, 6)),
+            (Range(4, 6, 2), Range(2, 16, 7), S.EmptySet),]:
+        assert a.intersect(b) == r
+        assert a.intersect(b.reversed) == r
+        assert a.reversed.intersect(b) == r
+        assert a.reversed.intersect(b.reversed) == r
+        a, b = b, a
+        assert a.intersect(b) == r
+        assert a.intersect(b.reversed) == r
+        assert a.reversed.intersect(b) == r
+        assert a.reversed.intersect(b.reversed) == r
+
+
+def test_range_interval_intersection():
+    p = symbols('p', positive=True)
+    assert isinstance(Range(3).intersect(Interval(p, p + 2)), Intersection)
+    assert Range(4).intersect(Interval(0, 3)) == Range(4)
+    assert Range(4).intersect(Interval(-oo, oo)) == Range(4)
+    assert Range(4).intersect(Interval(1, oo)) == Range(1, 4)
+    assert Range(4).intersect(Interval(1.1, oo)) == Range(2, 4)
+    assert Range(4).intersect(Interval(0.1, 3)) == Range(1, 4)
+    assert Range(4).intersect(Interval(0.1, 3.1)) == Range(1, 4)
+    assert Range(4).intersect(Interval.open(0, 3)) == Range(1, 3)
+    assert Range(4).intersect(Interval.open(0.1, 0.5)) is S.EmptySet
+    assert Interval(-1, 5).intersect(S.Complexes) == Interval(-1, 5)
+    assert Interval(-1, 5).intersect(S.Reals) == Interval(-1, 5)
+    assert Interval(-1, 5).intersect(S.Integers) == Range(-1, 6)
+    assert Interval(-1, 5).intersect(S.Naturals) == Range(1, 6)
+    assert Interval(-1, 5).intersect(S.Naturals0) == Range(0, 6)
+
+    # Null Range intersections
+    assert Range(0).intersect(Interval(0.2, 0.8)) is S.EmptySet
+    assert Range(0).intersect(Interval(-oo, oo)) is S.EmptySet
+
+
+def test_range_is_finite_set():
+    assert Range(-100, 100).is_finite_set is True
+    assert Range(2, oo).is_finite_set is False
+    assert Range(-oo, 50).is_finite_set is False
+    assert Range(-oo, oo).is_finite_set is False
+    assert Range(oo, -oo).is_finite_set is True
+    assert Range(0, 0).is_finite_set is True
+    assert Range(oo, oo).is_finite_set is True
+    assert Range(-oo, -oo).is_finite_set is True
+    n = Symbol('n', integer=True)
+    m = Symbol('m', integer=True)
+    assert Range(n, n + 49).is_finite_set is True
+    assert Range(n, 0).is_finite_set is True
+    assert Range(-3, n + 7).is_finite_set is True
+    assert Range(n, m).is_finite_set is True
+    assert Range(n + m, m - n).is_finite_set is True
+    assert Range(n, n + m + n).is_finite_set is True
+    assert Range(n, oo).is_finite_set is False
+    assert Range(-oo, n).is_finite_set is False
+    assert Range(n, -oo).is_finite_set is True
+    assert Range(oo, n).is_finite_set is True
+
+
+def test_Range_is_iterable():
+    assert Range(-100, 100).is_iterable is True
+    assert Range(2, oo).is_iterable is False
+    assert Range(-oo, 50).is_iterable is False
+    assert Range(-oo, oo).is_iterable is False
+    assert Range(oo, -oo).is_iterable is True
+    assert Range(0, 0).is_iterable is True
+    assert Range(oo, oo).is_iterable is True
+    assert Range(-oo, -oo).is_iterable is True
+    n = Symbol('n', integer=True)
+    m = Symbol('m', integer=True)
+    p = Symbol('p', integer=True, positive=True)
+    assert Range(n, n + 49).is_iterable is True
+    assert Range(n, 0).is_iterable is False
+    assert Range(-3, n + 7).is_iterable is False
+    assert Range(-3, p + 7).is_iterable is False # Should work with better __iter__
+    assert Range(n, m).is_iterable is False
+    assert Range(n + m, m - n).is_iterable is False
+    assert Range(n, n + m + n).is_iterable is False
+    assert Range(n, oo).is_iterable is False
+    assert Range(-oo, n).is_iterable is False
+    x = Symbol('x')
+    assert Range(x, x + 49).is_iterable is False
+    assert Range(x, 0).is_iterable is False
+    assert Range(-3, x + 7).is_iterable is False
+    assert Range(x, m).is_iterable is False
+    assert Range(x + m, m - x).is_iterable is False
+    assert Range(x, x + m + x).is_iterable is False
+    assert Range(x, oo).is_iterable is False
+    assert Range(-oo, x).is_iterable is False
+
+
+def test_Integers_eval_imageset():
+    ans = ImageSet(Lambda(x, 2*x + Rational(3, 7)), S.Integers)
+    im = imageset(Lambda(x, -2*x + Rational(3, 7)), S.Integers)
+    assert im == ans
+    im = imageset(Lambda(x, -2*x - Rational(11, 7)), S.Integers)
+    assert im == ans
+    y = Symbol('y')
+    L = imageset(x, 2*x + y, S.Integers)
+    assert y + 4 in L
+    a, b, c = 0.092, 0.433, 0.341
+    assert a in imageset(x, a + c*x, S.Integers)
+    assert b in imageset(x, b + c*x, S.Integers)
+
+    _x = symbols('x', negative=True)
+    eq = _x**2 - _x + 1
+    assert imageset(_x, eq, S.Integers).lamda.expr == _x**2 + _x + 1
+    eq = 3*_x - 1
+    assert imageset(_x, eq, S.Integers).lamda.expr == 3*_x + 2
+
+    assert imageset(x, (x, 1/x), S.Integers) == \
+        ImageSet(Lambda(x, (x, 1/x)), S.Integers)
+
+
+def test_Range_eval_imageset():
+    a, b, c = symbols('a b c')
+    assert imageset(x, a*(x + b) + c, Range(3)) == \
+        imageset(x, a*x + a*b + c, Range(3))
+    eq = (x + 1)**2
+    assert imageset(x, eq, Range(3)).lamda.expr == eq
+    eq = a*(x + b) + c
+    r = Range(3, -3, -2)
+    imset = imageset(x, eq, r)
+    assert imset.lamda.expr != eq
+    assert list(imset) == [eq.subs(x, i).expand() for i in list(r)]
+
+
+def test_fun():
+    assert (FiniteSet(*ImageSet(Lambda(x, sin(pi*x/4)),
+        Range(-10, 11))) == FiniteSet(-1, -sqrt(2)/2, 0, sqrt(2)/2, 1))
+
+
+def test_Range_is_empty():
+    i = Symbol('i', integer=True)
+    n = Symbol('n', negative=True, integer=True)
+    p = Symbol('p', positive=True, integer=True)
+
+    assert Range(0).is_empty
+    assert not Range(1).is_empty
+    assert Range(1, 0).is_empty
+    assert not Range(-1, 0).is_empty
+    assert Range(i).is_empty is None
+    assert Range(n).is_empty
+    assert Range(p).is_empty is False
+    assert Range(n, 0).is_empty is False
+    assert Range(n, p).is_empty is False
+    assert Range(p, n).is_empty
+    assert Range(n, -1).is_empty is None
+    assert Range(p, n, -1).is_empty is False
+
+
+def test_Reals():
+    assert 5 in S.Reals
+    assert S.Pi in S.Reals
+    assert -sqrt(2) in S.Reals
+    assert (2, 5) not in S.Reals
+    assert sqrt(-1) not in S.Reals
+    assert S.Reals == Interval(-oo, oo)
+    assert S.Reals != Interval(0, oo)
+    assert S.Reals.is_subset(Interval(-oo, oo))
+    assert S.Reals.intersect(Range(-oo, oo)) == Range(-oo, oo)
+    assert S.ComplexInfinity not in S.Reals
+    assert S.NaN not in S.Reals
+    assert x + S.ComplexInfinity not in S.Reals
+
+
+def test_Complex():
+    assert 5 in S.Complexes
+    assert 5 + 4*I in S.Complexes
+    assert S.Pi in S.Complexes
+    assert -sqrt(2) in S.Complexes
+    assert -I in S.Complexes
+    assert sqrt(-1) in S.Complexes
+    assert S.Complexes.intersect(S.Reals) == S.Reals
+    assert S.Complexes.union(S.Reals) == S.Complexes
+    assert S.Complexes == ComplexRegion(S.Reals*S.Reals)
+    assert (S.Complexes == ComplexRegion(Interval(1, 2)*Interval(3, 4))) == False
+    assert str(S.Complexes) == "Complexes"
+    assert repr(S.Complexes) == "Complexes"
+
+
+def take(n, iterable):
+    "Return first n items of the iterable as a list"
+    return list(itertools.islice(iterable, n))
+
+
+def test_intersections():
+    assert S.Integers.intersect(S.Reals) == S.Integers
+    assert 5 in S.Integers.intersect(S.Reals)
+    assert 5 in S.Integers.intersect(S.Reals)
+    assert -5 not in S.Naturals.intersect(S.Reals)
+    assert 5.5 not in S.Integers.intersect(S.Reals)
+    assert 5 in S.Integers.intersect(Interval(3, oo))
+    assert -5 in S.Integers.intersect(Interval(-oo, 3))
+    assert all(x.is_Integer
+            for x in take(10, S.Integers.intersect(Interval(3, oo)) ))
+
+
+def test_infinitely_indexed_set_1():
+    from sympy.abc import n, m
+    assert imageset(Lambda(n, n), S.Integers) == imageset(Lambda(m, m), S.Integers)
+
+    assert imageset(Lambda(n, 2*n), S.Integers).intersect(
+            imageset(Lambda(m, 2*m + 1), S.Integers)) is S.EmptySet
+
+    assert imageset(Lambda(n, 2*n), S.Integers).intersect(
+            imageset(Lambda(n, 2*n + 1), S.Integers)) is S.EmptySet
+
+    assert imageset(Lambda(m, 2*m), S.Integers).intersect(
+                imageset(Lambda(n, 3*n), S.Integers)).dummy_eq(
+            ImageSet(Lambda(t, 6*t), S.Integers))
+
+    assert imageset(x, x/2 + Rational(1, 3), S.Integers).intersect(S.Integers) is S.EmptySet
+    assert imageset(x, x/2 + S.Half, S.Integers).intersect(S.Integers) is S.Integers
+
+    # https://github.com/sympy/sympy/issues/17355
+    S53 = ImageSet(Lambda(n, 5*n + 3), S.Integers)
+    assert S53.intersect(S.Integers) == S53
+
+
+def test_infinitely_indexed_set_2():
+    from sympy.abc import n
+    a = Symbol('a', integer=True)
+    assert imageset(Lambda(n, n), S.Integers) == \
+        imageset(Lambda(n, n + a), S.Integers)
+    assert imageset(Lambda(n, n + pi), S.Integers) == \
+        imageset(Lambda(n, n + a + pi), S.Integers)
+    assert imageset(Lambda(n, n), S.Integers) == \
+        imageset(Lambda(n, -n + a), S.Integers)
+    assert imageset(Lambda(n, -6*n), S.Integers) == \
+        ImageSet(Lambda(n, 6*n), S.Integers)
+    assert imageset(Lambda(n, 2*n + pi), S.Integers) == \
+        ImageSet(Lambda(n, 2*n + pi - 2), S.Integers)
+
+
+def test_imageset_intersect_real():
+    from sympy.abc import n
+    assert imageset(Lambda(n, n + (n - 1)*(n + 1)*I), S.Integers).intersect(S.Reals) == FiniteSet(-1, 1)
+    im = (n - 1)*(n + S.Half)
+    assert imageset(Lambda(n, n + im*I), S.Integers
+        ).intersect(S.Reals) == FiniteSet(1)
+    assert imageset(Lambda(n, n + im*(n + 1)*I), S.Naturals0
+        ).intersect(S.Reals) == FiniteSet(1)
+    assert imageset(Lambda(n, n/2 + im.expand()*I), S.Integers
+        ).intersect(S.Reals) == ImageSet(Lambda(x, x/2), ConditionSet(
+        n, Eq(n**2 - n/2 - S(1)/2, 0), S.Integers))
+    assert imageset(Lambda(n, n/(1/n - 1) + im*(n + 1)*I), S.Integers
+        ).intersect(S.Reals) == FiniteSet(S.Half)
+    assert imageset(Lambda(n, n/(n - 6) +
+        (n - 3)*(n + 1)*I/(2*n + 2)), S.Integers).intersect(
+        S.Reals) == FiniteSet(-1)
+    assert imageset(Lambda(n, n/(n**2 - 9) +
+        (n - 3)*(n + 1)*I/(2*n + 2)), S.Integers).intersect(
+        S.Reals) is S.EmptySet
+    s = ImageSet(
+        Lambda(n, -I*(I*(2*pi*n - pi/4) + log(Abs(sqrt(-I))))),
+        S.Integers)
+    # s is unevaluated, but after intersection the result
+    # should be canonical
+    assert s.intersect(S.Reals) == imageset(
+        Lambda(n, 2*n*pi - pi/4), S.Integers) == ImageSet(
+        Lambda(n, 2*pi*n + pi*Rational(7, 4)), S.Integers)
+
+
+def test_imageset_intersect_interval():
+    from sympy.abc import n
+    f1 = ImageSet(Lambda(n, n*pi), S.Integers)
+    f2 = ImageSet(Lambda(n, 2*n), Interval(0, pi))
+    f3 = ImageSet(Lambda(n, 2*n*pi + pi/2), S.Integers)
+    # complex expressions
+    f4 = ImageSet(Lambda(n, n*I*pi), S.Integers)
+    f5 = ImageSet(Lambda(n, 2*I*n*pi + pi/2), S.Integers)
+    # non-linear expressions
+    f6 = ImageSet(Lambda(n, log(n)), S.Integers)
+    f7 = ImageSet(Lambda(n, n**2), S.Integers)
+    f8 = ImageSet(Lambda(n, Abs(n)), S.Integers)
+    f9 = ImageSet(Lambda(n, exp(n)), S.Naturals0)
+
+    assert f1.intersect(Interval(-1, 1)) == FiniteSet(0)
+    assert f1.intersect(Interval(0, 2*pi, False, True)) == FiniteSet(0, pi)
+    assert f2.intersect(Interval(1, 2)) == Interval(1, 2)
+    assert f3.intersect(Interval(-1, 1)) == S.EmptySet
+    assert f3.intersect(Interval(-5, 5)) == FiniteSet(pi*Rational(-3, 2), pi/2)
+    assert f4.intersect(Interval(-1, 1)) == FiniteSet(0)
+    assert f4.intersect(Interval(1, 2)) == S.EmptySet
+    assert f5.intersect(Interval(0, 1)) == S.EmptySet
+    assert f6.intersect(Interval(0, 1)) == FiniteSet(S.Zero, log(2))
+    assert f7.intersect(Interval(0, 10)) == Intersection(f7, Interval(0, 10))
+    assert f8.intersect(Interval(0, 2)) == Intersection(f8, Interval(0, 2))
+    assert f9.intersect(Interval(1, 2)) == Intersection(f9, Interval(1, 2))
+
+
+def test_imageset_intersect_diophantine():
+    from sympy.abc import m, n
+    # Check that same lambda variable for both ImageSets is handled correctly
+    img1 = ImageSet(Lambda(n, 2*n + 1), S.Integers)
+    img2 = ImageSet(Lambda(n, 4*n + 1), S.Integers)
+    assert img1.intersect(img2) == img2
+    # Empty solution set returned by diophantine:
+    assert ImageSet(Lambda(n, 2*n), S.Integers).intersect(
+            ImageSet(Lambda(n, 2*n + 1), S.Integers)) == S.EmptySet
+    # Check intersection with S.Integers:
+    assert ImageSet(Lambda(n, 9/n + 20*n/3), S.Integers).intersect(
+            S.Integers) == FiniteSet(-61, -23, 23, 61)
+    # Single solution (2, 3) for diophantine solution:
+    assert ImageSet(Lambda(n, (n - 2)**2), S.Integers).intersect(
+            ImageSet(Lambda(n, -(n - 3)**2), S.Integers)) == FiniteSet(0)
+    # Single parametric solution for diophantine solution:
+    assert ImageSet(Lambda(n, n**2 + 5), S.Integers).intersect(
+            ImageSet(Lambda(m, 2*m), S.Integers)).dummy_eq(ImageSet(
+            Lambda(n, 4*n**2 + 4*n + 6), S.Integers))
+    # 4 non-parametric solution couples for dioph. equation:
+    assert ImageSet(Lambda(n, n**2 - 9), S.Integers).intersect(
+            ImageSet(Lambda(m, -m**2), S.Integers)) == FiniteSet(-9, 0)
+    # Double parametric solution for diophantine solution:
+    assert ImageSet(Lambda(m, m**2 + 40), S.Integers).intersect(
+            ImageSet(Lambda(n, 41*n), S.Integers)).dummy_eq(Intersection(
+            ImageSet(Lambda(m, m**2 + 40), S.Integers),
+            ImageSet(Lambda(n, 41*n), S.Integers)))
+    # Check that diophantine returns *all* (8) solutions (permute=True)
+    assert ImageSet(Lambda(n, n**4 - 2**4), S.Integers).intersect(
+            ImageSet(Lambda(m, -m**4 + 3**4), S.Integers)) == FiniteSet(0, 65)
+    assert ImageSet(Lambda(n, pi/12 + n*5*pi/12), S.Integers).intersect(
+            ImageSet(Lambda(n, 7*pi/12 + n*11*pi/12), S.Integers)).dummy_eq(ImageSet(
+            Lambda(n, 55*pi*n/12 + 17*pi/4), S.Integers))
+    # TypeError raised by diophantine (#18081)
+    assert ImageSet(Lambda(n, n*log(2)), S.Integers).intersection(
+        S.Integers).dummy_eq(Intersection(ImageSet(
+        Lambda(n, n*log(2)), S.Integers), S.Integers))
+    # NotImplementedError raised by diophantine (no solver for cubic_thue)
+    assert ImageSet(Lambda(n, n**3 + 1), S.Integers).intersect(
+            ImageSet(Lambda(n, n**3), S.Integers)).dummy_eq(Intersection(
+            ImageSet(Lambda(n, n**3 + 1), S.Integers),
+            ImageSet(Lambda(n, n**3), S.Integers)))
+
+
+def test_infinitely_indexed_set_3():
+    from sympy.abc import n, m
+    assert imageset(Lambda(m, 2*pi*m), S.Integers).intersect(
+            imageset(Lambda(n, 3*pi*n), S.Integers)).dummy_eq(
+        ImageSet(Lambda(t, 6*pi*t), S.Integers))
+    assert imageset(Lambda(n, 2*n + 1), S.Integers) == \
+        imageset(Lambda(n, 2*n - 1), S.Integers)
+    assert imageset(Lambda(n, 3*n + 2), S.Integers) == \
+        imageset(Lambda(n, 3*n - 1), S.Integers)
+
+
+def test_ImageSet_simplification():
+    from sympy.abc import n, m
+    assert imageset(Lambda(n, n), S.Integers) == S.Integers
+    assert imageset(Lambda(n, sin(n)),
+                    imageset(Lambda(m, tan(m)), S.Integers)) == \
+            imageset(Lambda(m, sin(tan(m))), S.Integers)
+    assert imageset(n, 1 + 2*n, S.Naturals) == Range(3, oo, 2)
+    assert imageset(n, 1 + 2*n, S.Naturals0) == Range(1, oo, 2)
+    assert imageset(n, 1 - 2*n, S.Naturals) == Range(-1, -oo, -2)
+
+
+def test_ImageSet_contains():
+    assert (2, S.Half) in imageset(x, (x, 1/x), S.Integers)
+    assert imageset(x, x + I*3, S.Integers).intersection(S.Reals) is S.EmptySet
+    i = Dummy(integer=True)
+    q = imageset(x, x + I*y, S.Integers).intersection(S.Reals)
+    assert q.subs(y, I*i).intersection(S.Integers) is S.Integers
+    q = imageset(x, x + I*y/x, S.Integers).intersection(S.Reals)
+    assert q.subs(y, 0) is S.Integers
+    assert q.subs(y, I*i*x).intersection(S.Integers) is S.Integers
+    z = cos(1)**2 + sin(1)**2 - 1
+    q = imageset(x, x + I*z, S.Integers).intersection(S.Reals)
+    assert q is not S.EmptySet
+
+
+def test_ComplexRegion_contains():
+    r = Symbol('r', real=True)
+    # contains in ComplexRegion
+    a = Interval(2, 3)
+    b = Interval(4, 6)
+    c = Interval(7, 9)
+    c1 = ComplexRegion(a*b)
+    c2 = ComplexRegion(Union(a*b, c*a))
+    assert 2.5 + 4.5*I in c1
+    assert 2 + 4*I in c1
+    assert 3 + 4*I in c1
+    assert 8 + 2.5*I in c2
+    assert 2.5 + 6.1*I not in c1
+    assert 4.5 + 3.2*I not in c1
+    assert c1.contains(x) == Contains(x, c1, evaluate=False)
+    assert c1.contains(r) == False
+    assert c2.contains(x) == Contains(x, c2, evaluate=False)
+    assert c2.contains(r) == False
+
+    r1 = Interval(0, 1)
+    theta1 = Interval(0, 2*S.Pi)
+    c3 = ComplexRegion(r1*theta1, polar=True)
+    assert (0.5 + I*6/10) in c3
+    assert (S.Half + I*6/10) in c3
+    assert (S.Half + .6*I) in c3
+    assert (0.5 + .6*I) in c3
+    assert I in c3
+    assert 1 in c3
+    assert 0 in c3
+    assert 1 + I not in c3
+    assert 1 - I not in c3
+    assert c3.contains(x) == Contains(x, c3, evaluate=False)
+    assert c3.contains(r + 2*I) == Contains(
+        r + 2*I, c3, evaluate=False)  # is in fact False
+    assert c3.contains(1/(1 + r**2)) == Contains(
+        1/(1 + r**2), c3, evaluate=False)  # is in fact True
+
+    r2 = Interval(0, 3)
+    theta2 = Interval(pi, 2*pi, left_open=True)
+    c4 = ComplexRegion(r2*theta2, polar=True)
+    assert c4.contains(0) == True
+    assert c4.contains(2 + I) == False
+    assert c4.contains(-2 + I) == False
+    assert c4.contains(-2 - I) == True
+    assert c4.contains(2 - I) == True
+    assert c4.contains(-2) == False
+    assert c4.contains(2) == True
+    assert c4.contains(x) == Contains(x, c4, evaluate=False)
+    assert c4.contains(3/(1 + r**2)) == Contains(
+        3/(1 + r**2), c4, evaluate=False)  # is in fact True
+
+    raises(ValueError, lambda: ComplexRegion(r1*theta1, polar=2))
+
+
+def test_symbolic_Range():
+    n = Symbol('n')
+    raises(ValueError, lambda: Range(n)[0])
+    raises(IndexError, lambda: Range(n, n)[0])
+    raises(ValueError, lambda: Range(n, n+1)[0])
+    raises(ValueError, lambda: Range(n).size)
+
+    n = Symbol('n', integer=True)
+    raises(ValueError, lambda: Range(n)[0])
+    raises(IndexError, lambda: Range(n, n)[0])
+    assert Range(n, n+1)[0] == n
+    raises(ValueError, lambda: Range(n).size)
+    assert Range(n, n+1).size == 1
+
+    n = Symbol('n', integer=True, nonnegative=True)
+    raises(ValueError, lambda: Range(n)[0])
+    raises(IndexError, lambda: Range(n, n)[0])
+    assert Range(n+1)[0] == 0
+    assert Range(n, n+1)[0] == n
+    assert Range(n).size == n
+    assert Range(n+1).size == n+1
+    assert Range(n, n+1).size == 1
+
+    n = Symbol('n', integer=True, positive=True)
+    assert Range(n)[0] == 0
+    assert Range(n, n+1)[0] == n
+    assert Range(n).size == n
+    assert Range(n, n+1).size == 1
+
+    m = Symbol('m', integer=True, positive=True)
+
+    assert Range(n, n+m)[0] == n
+    assert Range(n, n+m).size == m
+    assert Range(n, n+1).size == 1
+    assert Range(n, n+m, 2).size == floor(m/2)
+
+    m = Symbol('m', integer=True, positive=True, even=True)
+    assert Range(n, n+m, 2).size == m/2
+
+
+def test_issue_18400():
+    n = Symbol('n', integer=True)
+    raises(ValueError, lambda: imageset(lambda x: x*2, Range(n)))
+
+    n = Symbol('n', integer=True, positive=True)
+    # No exception
+    assert imageset(lambda x: x*2, Range(n)) == imageset(lambda x: x*2, Range(n))
+
+
+def test_ComplexRegion_intersect():
+    # Polar form
+    X_axis = ComplexRegion(Interval(0, oo)*FiniteSet(0, S.Pi), polar=True)
+
+    unit_disk = ComplexRegion(Interval(0, 1)*Interval(0, 2*S.Pi), polar=True)
+    upper_half_unit_disk = ComplexRegion(Interval(0, 1)*Interval(0, S.Pi), polar=True)
+    upper_half_disk = ComplexRegion(Interval(0, oo)*Interval(0, S.Pi), polar=True)
+    lower_half_disk = ComplexRegion(Interval(0, oo)*Interval(S.Pi, 2*S.Pi), polar=True)
+    right_half_disk = ComplexRegion(Interval(0, oo)*Interval(-S.Pi/2, S.Pi/2), polar=True)
+    first_quad_disk = ComplexRegion(Interval(0, oo)*Interval(0, S.Pi/2), polar=True)
+
+    assert upper_half_disk.intersect(unit_disk) == upper_half_unit_disk
+    assert right_half_disk.intersect(first_quad_disk) == first_quad_disk
+    assert upper_half_disk.intersect(right_half_disk) == first_quad_disk
+    assert upper_half_disk.intersect(lower_half_disk) == X_axis
+
+    c1 = ComplexRegion(Interval(0, 4)*Interval(0, 2*S.Pi), polar=True)
+    assert c1.intersect(Interval(1, 5)) == Interval(1, 4)
+    assert c1.intersect(Interval(4, 9)) == FiniteSet(4)
+    assert c1.intersect(Interval(5, 12)) is S.EmptySet
+
+    # Rectangular form
+    X_axis = ComplexRegion(Interval(-oo, oo)*FiniteSet(0))
+
+    unit_square = ComplexRegion(Interval(-1, 1)*Interval(-1, 1))
+    upper_half_unit_square = ComplexRegion(Interval(-1, 1)*Interval(0, 1))
+    upper_half_plane = ComplexRegion(Interval(-oo, oo)*Interval(0, oo))
+    lower_half_plane = ComplexRegion(Interval(-oo, oo)*Interval(-oo, 0))
+    right_half_plane = ComplexRegion(Interval(0, oo)*Interval(-oo, oo))
+    first_quad_plane = ComplexRegion(Interval(0, oo)*Interval(0, oo))
+
+    assert upper_half_plane.intersect(unit_square) == upper_half_unit_square
+    assert right_half_plane.intersect(first_quad_plane) == first_quad_plane
+    assert upper_half_plane.intersect(right_half_plane) == first_quad_plane
+    assert upper_half_plane.intersect(lower_half_plane) == X_axis
+
+    c1 = ComplexRegion(Interval(-5, 5)*Interval(-10, 10))
+    assert c1.intersect(Interval(2, 7)) == Interval(2, 5)
+    assert c1.intersect(Interval(5, 7)) == FiniteSet(5)
+    assert c1.intersect(Interval(6, 9)) is S.EmptySet
+
+    # unevaluated object
+    C1 = ComplexRegion(Interval(0, 1)*Interval(0, 2*S.Pi), polar=True)
+    C2 = ComplexRegion(Interval(-1, 1)*Interval(-1, 1))
+    assert C1.intersect(C2) == Intersection(C1, C2, evaluate=False)
+
+
+def test_ComplexRegion_union():
+    # Polar form
+    c1 = ComplexRegion(Interval(0, 1)*Interval(0, 2*S.Pi), polar=True)
+    c2 = ComplexRegion(Interval(0, 1)*Interval(0, S.Pi), polar=True)
+    c3 = ComplexRegion(Interval(0, oo)*Interval(0, S.Pi), polar=True)
+    c4 = ComplexRegion(Interval(0, oo)*Interval(S.Pi, 2*S.Pi), polar=True)
+
+    p1 = Union(Interval(0, 1)*Interval(0, 2*S.Pi), Interval(0, 1)*Interval(0, S.Pi))
+    p2 = Union(Interval(0, oo)*Interval(0, S.Pi), Interval(0, oo)*Interval(S.Pi, 2*S.Pi))
+
+    assert c1.union(c2) == ComplexRegion(p1, polar=True)
+    assert c3.union(c4) == ComplexRegion(p2, polar=True)
+
+    # Rectangular form
+    c5 = ComplexRegion(Interval(2, 5)*Interval(6, 9))
+    c6 = ComplexRegion(Interval(4, 6)*Interval(10, 12))
+    c7 = ComplexRegion(Interval(0, 10)*Interval(-10, 0))
+    c8 = ComplexRegion(Interval(12, 16)*Interval(14, 20))
+
+    p3 = Union(Interval(2, 5)*Interval(6, 9), Interval(4, 6)*Interval(10, 12))
+    p4 = Union(Interval(0, 10)*Interval(-10, 0), Interval(12, 16)*Interval(14, 20))
+
+    assert c5.union(c6) == ComplexRegion(p3)
+    assert c7.union(c8) == ComplexRegion(p4)
+
+    assert c1.union(Interval(2, 4)) == Union(c1, Interval(2, 4), evaluate=False)
+    assert c5.union(Interval(2, 4)) == Union(c5, ComplexRegion.from_real(Interval(2, 4)))
+
+
+def test_ComplexRegion_from_real():
+    c1 = ComplexRegion(Interval(0, 1) * Interval(0, 2 * S.Pi), polar=True)
+
+    raises(ValueError, lambda: c1.from_real(c1))
+    assert c1.from_real(Interval(-1, 1)) == ComplexRegion(Interval(-1, 1) * FiniteSet(0), False)
+
+
+def test_ComplexRegion_measure():
+    a, b = Interval(2, 5), Interval(4, 8)
+    theta1, theta2 = Interval(0, 2*S.Pi), Interval(0, S.Pi)
+    c1 = ComplexRegion(a*b)
+    c2 = ComplexRegion(Union(a*theta1, b*theta2), polar=True)
+
+    assert c1.measure == 12
+    assert c2.measure == 9*pi
+
+
+def test_normalize_theta_set():
+    # Interval
+    assert normalize_theta_set(Interval(pi, 2*pi)) == \
+        Union(FiniteSet(0), Interval.Ropen(pi, 2*pi))
+    assert normalize_theta_set(Interval(pi*Rational(9, 2), 5*pi)) == Interval(pi/2, pi)
+    assert normalize_theta_set(Interval(pi*Rational(-3, 2), pi/2)) == Interval.Ropen(0, 2*pi)
+    assert normalize_theta_set(Interval.open(pi*Rational(-3, 2), pi/2)) == \
+        Union(Interval.Ropen(0, pi/2), Interval.open(pi/2, 2*pi))
+    assert normalize_theta_set(Interval.open(pi*Rational(-7, 2), pi*Rational(-3, 2))) == \
+        Union(Interval.Ropen(0, pi/2), Interval.open(pi/2, 2*pi))
+    assert normalize_theta_set(Interval(-pi/2, pi/2)) == \
+        Union(Interval(0, pi/2), Interval.Ropen(pi*Rational(3, 2), 2*pi))
+    assert normalize_theta_set(Interval.open(-pi/2, pi/2)) == \
+        Union(Interval.Ropen(0, pi/2), Interval.open(pi*Rational(3, 2), 2*pi))
+    assert normalize_theta_set(Interval(-4*pi, 3*pi)) == Interval.Ropen(0, 2*pi)
+    assert normalize_theta_set(Interval(pi*Rational(-3, 2), -pi/2)) == Interval(pi/2, pi*Rational(3, 2))
+    assert normalize_theta_set(Interval.open(0, 2*pi)) == Interval.open(0, 2*pi)
+    assert normalize_theta_set(Interval.Ropen(-pi/2, pi/2)) == \
+        Union(Interval.Ropen(0, pi/2), Interval.Ropen(pi*Rational(3, 2), 2*pi))
+    assert normalize_theta_set(Interval.Lopen(-pi/2, pi/2)) == \
+        Union(Interval(0, pi/2), Interval.open(pi*Rational(3, 2), 2*pi))
+    assert normalize_theta_set(Interval(-pi/2, pi/2)) == \
+        Union(Interval(0, pi/2), Interval.Ropen(pi*Rational(3, 2), 2*pi))
+    assert normalize_theta_set(Interval.open(4*pi, pi*Rational(9, 2))) == Interval.open(0, pi/2)
+    assert normalize_theta_set(Interval.Lopen(4*pi, pi*Rational(9, 2))) == Interval.Lopen(0, pi/2)
+    assert normalize_theta_set(Interval.Ropen(4*pi, pi*Rational(9, 2))) == Interval.Ropen(0, pi/2)
+    assert normalize_theta_set(Interval.open(3*pi, 5*pi)) == \
+        Union(Interval.Ropen(0, pi), Interval.open(pi, 2*pi))
+
+    # FiniteSet
+    assert normalize_theta_set(FiniteSet(0, pi, 3*pi)) == FiniteSet(0, pi)
+    assert normalize_theta_set(FiniteSet(0, pi/2, pi, 2*pi)) == FiniteSet(0, pi/2, pi)
+    assert normalize_theta_set(FiniteSet(0, -pi/2, -pi, -2*pi)) == FiniteSet(0, pi, pi*Rational(3, 2))
+    assert normalize_theta_set(FiniteSet(pi*Rational(-3, 2), pi/2)) == \
+        FiniteSet(pi/2)
+    assert normalize_theta_set(FiniteSet(2*pi)) == FiniteSet(0)
+
+    # Unions
+    assert normalize_theta_set(Union(Interval(0, pi/3), Interval(pi/2, pi))) == \
+        Union(Interval(0, pi/3), Interval(pi/2, pi))
+    assert normalize_theta_set(Union(Interval(0, pi), Interval(2*pi, pi*Rational(7, 3)))) == \
+        Interval(0, pi)
+
+    # ValueError for non-real sets
+    raises(ValueError, lambda: normalize_theta_set(S.Complexes))
+
+    # NotImplementedError for subset of reals
+    raises(NotImplementedError, lambda: normalize_theta_set(Interval(0, 1)))
+
+    # NotImplementedError without pi as coefficient
+    raises(NotImplementedError, lambda: normalize_theta_set(Interval(1, 2*pi)))
+    raises(NotImplementedError, lambda: normalize_theta_set(Interval(2*pi, 10)))
+    raises(NotImplementedError, lambda: normalize_theta_set(FiniteSet(0, 3, 3*pi)))
+
+
+def test_ComplexRegion_FiniteSet():
+    x, y, z, a, b, c = symbols('x y z a b c')
+
+    # Issue #9669
+    assert ComplexRegion(FiniteSet(a, b, c)*FiniteSet(x, y, z)) == \
+        FiniteSet(a + I*x, a + I*y, a + I*z, b + I*x, b + I*y,
+                  b + I*z, c + I*x, c + I*y, c + I*z)
+    assert ComplexRegion(FiniteSet(2)*FiniteSet(3)) == FiniteSet(2 + 3*I)
+
+
+def test_union_RealSubSet():
+    assert (S.Complexes).union(Interval(1, 2)) == S.Complexes
+    assert (S.Complexes).union(S.Integers) == S.Complexes
+
+
+def test_SetKind_fancySet():
+    G = lambda *args: ImageSet(Lambda(x, x ** 2), *args)
+    assert G(Interval(1, 4)).kind is SetKind(NumberKind)
+    assert G(FiniteSet(1, 4)).kind is SetKind(NumberKind)
+    assert S.Rationals.kind is SetKind(NumberKind)
+    assert S.Naturals.kind is SetKind(NumberKind)
+    assert S.Integers.kind is SetKind(NumberKind)
+    assert Range(3).kind is SetKind(NumberKind)
+    a = Interval(2, 3)
+    b = Interval(4, 6)
+    c1 = ComplexRegion(a*b)
+    assert c1.kind is SetKind(TupleKind(NumberKind, NumberKind))
+
+
+def test_issue_9980():
+    c1 = ComplexRegion(Interval(1, 2)*Interval(2, 3))
+    c2 = ComplexRegion(Interval(1, 5)*Interval(1, 3))
+    R = Union(c1, c2)
+    assert simplify(R) == ComplexRegion(Union(Interval(1, 2)*Interval(2, 3), \
+                                    Interval(1, 5)*Interval(1, 3)), False)
+    assert c1.func(*c1.args) == c1
+    assert R.func(*R.args) == R
+
+
+def test_issue_11732():
+    interval12 = Interval(1, 2)
+    finiteset1234 = FiniteSet(1, 2, 3, 4)
+    pointComplex = Tuple(1, 5)
+
+    assert (interval12 in S.Naturals) == False
+    assert (interval12 in S.Naturals0) == False
+    assert (interval12 in S.Integers) == False
+    assert (interval12 in S.Complexes) == False
+
+    assert (finiteset1234 in S.Naturals) == False
+    assert (finiteset1234 in S.Naturals0) == False
+    assert (finiteset1234 in S.Integers) == False
+    assert (finiteset1234 in S.Complexes) == False
+
+    assert (pointComplex in S.Naturals) == False
+    assert (pointComplex in S.Naturals0) == False
+    assert (pointComplex in S.Integers) == False
+    assert (pointComplex in S.Complexes) == True
+
+
+def test_issue_11730():
+    unit = Interval(0, 1)
+    square = ComplexRegion(unit ** 2)
+
+    assert Union(S.Complexes, FiniteSet(oo)) != S.Complexes
+    assert Union(S.Complexes, FiniteSet(eye(4))) != S.Complexes
+    assert Union(unit, square) == square
+    assert Intersection(S.Reals, square) == unit
+
+
+def test_issue_11938():
+    unit = Interval(0, 1)
+    ival = Interval(1, 2)
+    cr1 = ComplexRegion(ival * unit)
+
+    assert Intersection(cr1, S.Reals) == ival
+    assert Intersection(cr1, unit) == FiniteSet(1)
+
+    arg1 = Interval(0, S.Pi)
+    arg2 = FiniteSet(S.Pi)
+    arg3 = Interval(S.Pi / 4, 3 * S.Pi / 4)
+    cp1 = ComplexRegion(unit * arg1, polar=True)
+    cp2 = ComplexRegion(unit * arg2, polar=True)
+    cp3 = ComplexRegion(unit * arg3, polar=True)
+
+    assert Intersection(cp1, S.Reals) == Interval(-1, 1)
+    assert Intersection(cp2, S.Reals) == Interval(-1, 0)
+    assert Intersection(cp3, S.Reals) == FiniteSet(0)
+
+
+def test_issue_11914():
+    a, b = Interval(0, 1), Interval(0, pi)
+    c, d = Interval(2, 3), Interval(pi, 3 * pi / 2)
+    cp1 = ComplexRegion(a * b, polar=True)
+    cp2 = ComplexRegion(c * d, polar=True)
+
+    assert -3 in cp1.union(cp2)
+    assert -3 in cp2.union(cp1)
+    assert -5 not in cp1.union(cp2)
+
+
+def test_issue_9543():
+    assert ImageSet(Lambda(x, x**2), S.Naturals).is_subset(S.Reals)
+
+
+def test_issue_16871():
+    assert ImageSet(Lambda(x, x), FiniteSet(1)) == {1}
+    assert ImageSet(Lambda(x, x - 3), S.Integers
+        ).intersection(S.Integers) is S.Integers
+
+
+@XFAIL
+def test_issue_16871b():
+    assert ImageSet(Lambda(x, x - 3), S.Integers).is_subset(S.Integers)
+
+
+def test_issue_18050():
+    assert imageset(Lambda(x, I*x + 1), S.Integers
+        ) == ImageSet(Lambda(x, I*x + 1), S.Integers)
+    assert imageset(Lambda(x, 3*I*x + 4 + 8*I), S.Integers
+        ) == ImageSet(Lambda(x, 3*I*x + 4 + 2*I), S.Integers)
+    # no 'Mod' for next 2 tests:
+    assert imageset(Lambda(x, 2*x + 3*I), S.Integers
+        ) == ImageSet(Lambda(x, 2*x + 3*I), S.Integers)
+    r = Symbol('r', positive=True)
+    assert imageset(Lambda(x, r*x + 10), S.Integers
+        ) == ImageSet(Lambda(x, r*x + 10), S.Integers)
+    # reduce real part:
+    assert imageset(Lambda(x, 3*x + 8 + 5*I), S.Integers
+        ) == ImageSet(Lambda(x, 3*x + 2 + 5*I), S.Integers)
+
+
+def test_Rationals():
+    assert S.Integers.is_subset(S.Rationals)
+    assert S.Naturals.is_subset(S.Rationals)
+    assert S.Naturals0.is_subset(S.Rationals)
+    assert S.Rationals.is_subset(S.Reals)
+    assert S.Rationals.inf is -oo
+    assert S.Rationals.sup is oo
+    it = iter(S.Rationals)
+    assert [next(it) for i in range(12)] == [
+        0, 1, -1, S.Half, 2, Rational(-1, 2), -2,
+        Rational(1, 3), 3, Rational(-1, 3), -3, Rational(2, 3)]
+    assert Basic() not in S.Rationals
+    assert S.Half in S.Rationals
+    assert S.Rationals.contains(0.5) == Contains(0.5, S.Rationals, evaluate=False)
+    assert 2 in S.Rationals
+    r = symbols('r', rational=True)
+    assert r in S.Rationals
+    raises(TypeError, lambda: x in S.Rationals)
+    # issue #18134:
+    assert S.Rationals.boundary == S.Reals
+    assert S.Rationals.closure == S.Reals
+    assert S.Rationals.is_open == False
+    assert S.Rationals.is_closed == False
+
+
+def test_NZQRC_unions():
+    # check that all trivial number set unions are simplified:
+    nbrsets = (S.Naturals, S.Naturals0, S.Integers, S.Rationals,
+        S.Reals, S.Complexes)
+    unions = (Union(a, b) for a in nbrsets for b in nbrsets)
+    assert all(u.is_Union is False for u in unions)
+
+
+def test_imageset_intersection():
+    n = Dummy()
+    s = ImageSet(Lambda(n, -I*(I*(2*pi*n - pi/4) +
+        log(Abs(sqrt(-I))))), S.Integers)
+    assert s.intersect(S.Reals) == ImageSet(
+        Lambda(n, 2*pi*n + pi*Rational(7, 4)), S.Integers)
+
+
+def test_issue_17858():
+    assert 1 in Range(-oo, oo)
+    assert 0 in Range(oo, -oo, -1)
+    assert oo not in Range(-oo, oo)
+    assert -oo not in Range(-oo, oo)
+
+def test_issue_17859():
+    r = Range(-oo,oo)
+    raises(ValueError,lambda: r[::2])
+    raises(ValueError, lambda: r[::-2])
+    r = Range(oo,-oo,-1)
+    raises(ValueError,lambda: r[::2])
+    raises(ValueError, lambda: r[::-2])

venv/lib/python3.10/site-packages/sympy/sets/tests/test_ordinals.py

@@ -0,0 +1,67 @@
+from sympy.sets.ordinals import Ordinal, OmegaPower, ord0, omega
+from sympy.testing.pytest import raises
+
+def test_string_ordinals():
+    assert str(omega) == 'w'
+    assert str(Ordinal(OmegaPower(5, 3), OmegaPower(3, 2))) == 'w**5*3 + w**3*2'
+    assert str(Ordinal(OmegaPower(5, 3), OmegaPower(0, 5))) == 'w**5*3 + 5'
+    assert str(Ordinal(OmegaPower(1, 3), OmegaPower(0, 5))) == 'w*3 + 5'
+    assert str(Ordinal(OmegaPower(omega + 1, 1), OmegaPower(3, 2))) == 'w**(w + 1) + w**3*2'
+
+def test_addition_with_integers():
+    assert 3 + Ordinal(OmegaPower(5, 3)) == Ordinal(OmegaPower(5, 3))
+    assert Ordinal(OmegaPower(5, 3))+3 == Ordinal(OmegaPower(5, 3), OmegaPower(0, 3))
+    assert Ordinal(OmegaPower(5, 3), OmegaPower(0, 2))+3 == \
+        Ordinal(OmegaPower(5, 3), OmegaPower(0, 5))
+
+
+def test_addition_with_ordinals():
+    assert Ordinal(OmegaPower(5, 3), OmegaPower(3, 2)) + Ordinal(OmegaPower(3, 3)) == \
+        Ordinal(OmegaPower(5, 3), OmegaPower(3, 5))
+    assert Ordinal(OmegaPower(5, 3), OmegaPower(3, 2)) + Ordinal(OmegaPower(4, 2)) == \
+        Ordinal(OmegaPower(5, 3), OmegaPower(4, 2))
+    assert Ordinal(OmegaPower(omega, 2), OmegaPower(3, 2)) + Ordinal(OmegaPower(4, 2)) == \
+        Ordinal(OmegaPower(omega, 2), OmegaPower(4, 2))
+
+def test_comparison():
+    assert Ordinal(OmegaPower(5, 3)) > Ordinal(OmegaPower(4, 3), OmegaPower(2, 1))
+    assert Ordinal(OmegaPower(5, 3), OmegaPower(3, 2)) < Ordinal(OmegaPower(5, 4))
+    assert Ordinal(OmegaPower(5, 4)) < Ordinal(OmegaPower(5, 5), OmegaPower(4, 1))
+
+    assert Ordinal(OmegaPower(5, 3), OmegaPower(3, 2)) == \
+        Ordinal(OmegaPower(5, 3), OmegaPower(3, 2))
+    assert not Ordinal(OmegaPower(5, 3), OmegaPower(3, 2)) == Ordinal(OmegaPower(5, 3))
+    assert Ordinal(OmegaPower(omega, 3)) > Ordinal(OmegaPower(5, 3))
+
+def test_multiplication_with_integers():
+    w = omega
+    assert 3*w == w
+    assert w*9 == Ordinal(OmegaPower(1, 9))
+
+def test_multiplication():
+    w = omega
+    assert w*(w + 1) == w*w + w
+    assert (w + 1)*(w + 1) ==  w*w + w + 1
+    assert w*1 == w
+    assert 1*w == w
+    assert w*ord0 == ord0
+    assert ord0*w == ord0
+    assert w**w == w * w**w
+    assert (w**w)*w*w == w**(w + 2)
+
+def test_exponentiation():
+    w = omega
+    assert w**2 == w*w
+    assert w**3 == w*w*w
+    assert w**(w + 1) == Ordinal(OmegaPower(omega + 1, 1))
+    assert (w**w)*(w**w) == w**(w*2)
+
+def test_comapre_not_instance():
+    w = OmegaPower(omega + 1, 1)
+    assert(not (w == None))
+    assert(not (w < 5))
+    raises(TypeError, lambda: w < 6.66)
+
+def test_is_successort():
+    w = Ordinal(OmegaPower(5, 1))
+    assert not w.is_successor_ordinal

venv/lib/python3.10/site-packages/sympy/sets/tests/test_powerset.py

@@ -0,0 +1,141 @@
+from sympy.core.expr import unchanged
+from sympy.core.singleton import S
+from sympy.core.symbol import Symbol
+from sympy.sets.contains import Contains
+from sympy.sets.fancysets import Interval
+from sympy.sets.powerset import PowerSet
+from sympy.sets.sets import FiniteSet
+from sympy.testing.pytest import raises, XFAIL
+
+
+def test_powerset_creation():
+    assert unchanged(PowerSet, FiniteSet(1, 2))
+    assert unchanged(PowerSet, S.EmptySet)
+    raises(ValueError, lambda: PowerSet(123))
+    assert unchanged(PowerSet, S.Reals)
+    assert unchanged(PowerSet, S.Integers)
+
+
+def test_powerset_rewrite_FiniteSet():
+    assert PowerSet(FiniteSet(1, 2)).rewrite(FiniteSet) == \
+        FiniteSet(S.EmptySet, FiniteSet(1), FiniteSet(2), FiniteSet(1, 2))
+    assert PowerSet(S.EmptySet).rewrite(FiniteSet) == FiniteSet(S.EmptySet)
+    assert PowerSet(S.Naturals).rewrite(FiniteSet) == PowerSet(S.Naturals)
+
+
+def test_finiteset_rewrite_powerset():
+    assert FiniteSet(S.EmptySet).rewrite(PowerSet) == PowerSet(S.EmptySet)
+    assert FiniteSet(
+        S.EmptySet, FiniteSet(1),
+        FiniteSet(2), FiniteSet(1, 2)).rewrite(PowerSet) == \
+            PowerSet(FiniteSet(1, 2))
+    assert FiniteSet(1, 2, 3).rewrite(PowerSet) == FiniteSet(1, 2, 3)
+
+
+def test_powerset__contains__():
+    subset_series = [
+        S.EmptySet,
+        FiniteSet(1, 2),
+        S.Naturals,
+        S.Naturals0,
+        S.Integers,
+        S.Rationals,
+        S.Reals,
+        S.Complexes]
+
+    l = len(subset_series)
+    for i in range(l):
+        for j in range(l):
+            if i <= j:
+                assert subset_series[i] in \
+                    PowerSet(subset_series[j], evaluate=False)
+            else:
+                assert subset_series[i] not in \
+                    PowerSet(subset_series[j], evaluate=False)
+
+
+@XFAIL
+def test_failing_powerset__contains__():
+    # XXX These are failing when evaluate=True,
+    # but using unevaluated PowerSet works fine.
+    assert FiniteSet(1, 2) not in PowerSet(S.EmptySet).rewrite(FiniteSet)
+    assert S.Naturals not in PowerSet(S.EmptySet).rewrite(FiniteSet)
+    assert S.Naturals not in PowerSet(FiniteSet(1, 2)).rewrite(FiniteSet)
+    assert S.Naturals0 not in PowerSet(S.EmptySet).rewrite(FiniteSet)
+    assert S.Naturals0 not in PowerSet(FiniteSet(1, 2)).rewrite(FiniteSet)
+    assert S.Integers not in PowerSet(S.EmptySet).rewrite(FiniteSet)
+    assert S.Integers not in PowerSet(FiniteSet(1, 2)).rewrite(FiniteSet)
+    assert S.Rationals not in PowerSet(S.EmptySet).rewrite(FiniteSet)
+    assert S.Rationals not in PowerSet(FiniteSet(1, 2)).rewrite(FiniteSet)
+    assert S.Reals not in PowerSet(S.EmptySet).rewrite(FiniteSet)
+    assert S.Reals not in PowerSet(FiniteSet(1, 2)).rewrite(FiniteSet)
+    assert S.Complexes not in PowerSet(S.EmptySet).rewrite(FiniteSet)
+    assert S.Complexes not in PowerSet(FiniteSet(1, 2)).rewrite(FiniteSet)
+
+
+def test_powerset__len__():
+    A = PowerSet(S.EmptySet, evaluate=False)
+    assert len(A) == 1
+    A = PowerSet(A, evaluate=False)
+    assert len(A) == 2
+    A = PowerSet(A, evaluate=False)
+    assert len(A) == 4
+    A = PowerSet(A, evaluate=False)
+    assert len(A) == 16
+
+
+def test_powerset__iter__():
+    a = PowerSet(FiniteSet(1, 2)).__iter__()
+    assert next(a) == S.EmptySet
+    assert next(a) == FiniteSet(1)
+    assert next(a) == FiniteSet(2)
+    assert next(a) == FiniteSet(1, 2)
+
+    a = PowerSet(S.Naturals).__iter__()
+    assert next(a) == S.EmptySet
+    assert next(a) == FiniteSet(1)
+    assert next(a) == FiniteSet(2)
+    assert next(a) == FiniteSet(1, 2)
+    assert next(a) == FiniteSet(3)
+    assert next(a) == FiniteSet(1, 3)
+    assert next(a) == FiniteSet(2, 3)
+    assert next(a) == FiniteSet(1, 2, 3)
+
+
+def test_powerset_contains():
+    A = PowerSet(FiniteSet(1), evaluate=False)
+    assert A.contains(2) == Contains(2, A)
+
+    x = Symbol('x')
+
+    A = PowerSet(FiniteSet(x), evaluate=False)
+    assert A.contains(FiniteSet(1)) == Contains(FiniteSet(1), A)
+
+
+def test_powerset_method():
+    # EmptySet
+    A = FiniteSet()
+    pset = A.powerset()
+    assert len(pset) == 1
+    assert pset ==  FiniteSet(S.EmptySet)
+
+    # FiniteSets
+    A = FiniteSet(1, 2)
+    pset = A.powerset()
+    assert len(pset) == 2**len(A)
+    assert pset == FiniteSet(FiniteSet(), FiniteSet(1),
+                             FiniteSet(2), A)
+    # Not finite sets
+    A = Interval(0, 1)
+    assert A.powerset() == PowerSet(A)
+
+def test_is_subset():
+    # covers line 101-102
+    # initialize powerset(1), which is a subset of powerset(1,2)
+    subset = PowerSet(FiniteSet(1))
+    pset = PowerSet(FiniteSet(1, 2))
+    bad_set = PowerSet(FiniteSet(2, 3))
+    # assert "subset" is subset of pset == True
+    assert subset.is_subset(pset)
+    # assert "bad_set" is subset of pset == False
+    assert not pset.is_subset(bad_set)

venv/lib/python3.10/site-packages/sympy/sets/tests/test_setexpr.py

@@ -0,0 +1,317 @@
+from sympy.sets.setexpr import SetExpr
+from sympy.sets import Interval, FiniteSet, Intersection, ImageSet, Union
+
+from sympy.core.expr import Expr
+from sympy.core.function import Lambda
+from sympy.core.numbers import (I, Rational, oo)
+from sympy.core.singleton import S
+from sympy.core.symbol import (Dummy, Symbol, symbols)
+from sympy.functions.elementary.exponential import (exp, log)
+from sympy.functions.elementary.miscellaneous import (Max, Min, sqrt)
+from sympy.functions.elementary.trigonometric import cos
+from sympy.sets.sets import Set
+
+
+a, x = symbols("a, x")
+_d = Dummy("d")
+
+
+def test_setexpr():
+    se = SetExpr(Interval(0, 1))
+    assert isinstance(se.set, Set)
+    assert isinstance(se, Expr)
+
+
+def test_scalar_funcs():
+    assert SetExpr(Interval(0, 1)).set == Interval(0, 1)
+    a, b = Symbol('a', real=True), Symbol('b', real=True)
+    a, b = 1, 2
+    # TODO: add support for more functions in the future:
+    for f in [exp, log]:
+        input_se = f(SetExpr(Interval(a, b)))
+        output = input_se.set
+        expected = Interval(Min(f(a), f(b)), Max(f(a), f(b)))
+        assert output == expected
+
+
+def test_Add_Mul():
+    assert (SetExpr(Interval(0, 1)) + 1).set == Interval(1, 2)
+    assert (SetExpr(Interval(0, 1))*2).set == Interval(0, 2)
+
+
+def test_Pow():
+    assert (SetExpr(Interval(0, 2))**2).set == Interval(0, 4)
+
+
+def test_compound():
+    assert (exp(SetExpr(Interval(0, 1))*2 + 1)).set == \
+           Interval(exp(1), exp(3))
+
+
+def test_Interval_Interval():
+    assert (SetExpr(Interval(1, 2)) + SetExpr(Interval(10, 20))).set == \
+           Interval(11, 22)
+    assert (SetExpr(Interval(1, 2))*SetExpr(Interval(10, 20))).set == \
+           Interval(10, 40)
+
+
+def test_FiniteSet_FiniteSet():
+    assert (SetExpr(FiniteSet(1, 2, 3)) + SetExpr(FiniteSet(1, 2))).set == \
+           FiniteSet(2, 3, 4, 5)
+    assert (SetExpr(FiniteSet(1, 2, 3))*SetExpr(FiniteSet(1, 2))).set == \
+           FiniteSet(1, 2, 3, 4, 6)
+
+
+def test_Interval_FiniteSet():
+    assert (SetExpr(FiniteSet(1, 2)) + SetExpr(Interval(0, 10))).set == \
+           Interval(1, 12)
+
+
+def test_Many_Sets():
+    assert (SetExpr(Interval(0, 1)) +
+            SetExpr(Interval(2, 3)) +
+            SetExpr(FiniteSet(10, 11, 12))).set == Interval(12, 16)
+
+
+def test_same_setexprs_are_not_identical():
+    a = SetExpr(FiniteSet(0, 1))
+    b = SetExpr(FiniteSet(0, 1))
+    assert (a + b).set == FiniteSet(0, 1, 2)
+
+    # Cannot detect the set being the same:
+    # assert (a + a).set == FiniteSet(0, 2)
+
+
+def test_Interval_arithmetic():
+    i12cc = SetExpr(Interval(1, 2))
+    i12lo = SetExpr(Interval.Lopen(1, 2))
+    i12ro = SetExpr(Interval.Ropen(1, 2))
+    i12o = SetExpr(Interval.open(1, 2))
+
+    n23cc = SetExpr(Interval(-2, 3))
+    n23lo = SetExpr(Interval.Lopen(-2, 3))
+    n23ro = SetExpr(Interval.Ropen(-2, 3))
+    n23o = SetExpr(Interval.open(-2, 3))
+
+    n3n2cc = SetExpr(Interval(-3, -2))
+
+    assert i12cc + i12cc == SetExpr(Interval(2, 4))
+    assert i12cc - i12cc == SetExpr(Interval(-1, 1))
+    assert i12cc*i12cc == SetExpr(Interval(1, 4))
+    assert i12cc/i12cc == SetExpr(Interval(S.Half, 2))
+    assert i12cc**2 == SetExpr(Interval(1, 4))
+    assert i12cc**3 == SetExpr(Interval(1, 8))
+
+    assert i12lo + i12ro == SetExpr(Interval.open(2, 4))
+    assert i12lo - i12ro == SetExpr(Interval.Lopen(-1, 1))
+    assert i12lo*i12ro == SetExpr(Interval.open(1, 4))
+    assert i12lo/i12ro == SetExpr(Interval.Lopen(S.Half, 2))
+    assert i12lo + i12lo == SetExpr(Interval.Lopen(2, 4))
+    assert i12lo - i12lo == SetExpr(Interval.open(-1, 1))
+    assert i12lo*i12lo == SetExpr(Interval.Lopen(1, 4))
+    assert i12lo/i12lo == SetExpr(Interval.open(S.Half, 2))
+    assert i12lo + i12cc == SetExpr(Interval.Lopen(2, 4))
+    assert i12lo - i12cc == SetExpr(Interval.Lopen(-1, 1))
+    assert i12lo*i12cc == SetExpr(Interval.Lopen(1, 4))
+    assert i12lo/i12cc == SetExpr(Interval.Lopen(S.Half, 2))
+    assert i12lo + i12o == SetExpr(Interval.open(2, 4))
+    assert i12lo - i12o == SetExpr(Interval.open(-1, 1))
+    assert i12lo*i12o == SetExpr(Interval.open(1, 4))
+    assert i12lo/i12o == SetExpr(Interval.open(S.Half, 2))
+    assert i12lo**2 == SetExpr(Interval.Lopen(1, 4))
+    assert i12lo**3 == SetExpr(Interval.Lopen(1, 8))
+
+    assert i12ro + i12ro == SetExpr(Interval.Ropen(2, 4))
+    assert i12ro - i12ro == SetExpr(Interval.open(-1, 1))
+    assert i12ro*i12ro == SetExpr(Interval.Ropen(1, 4))
+    assert i12ro/i12ro == SetExpr(Interval.open(S.Half, 2))
+    assert i12ro + i12cc == SetExpr(Interval.Ropen(2, 4))
+    assert i12ro - i12cc == SetExpr(Interval.Ropen(-1, 1))
+    assert i12ro*i12cc == SetExpr(Interval.Ropen(1, 4))
+    assert i12ro/i12cc == SetExpr(Interval.Ropen(S.Half, 2))
+    assert i12ro + i12o == SetExpr(Interval.open(2, 4))
+    assert i12ro - i12o == SetExpr(Interval.open(-1, 1))
+    assert i12ro*i12o == SetExpr(Interval.open(1, 4))
+    assert i12ro/i12o == SetExpr(Interval.open(S.Half, 2))
+    assert i12ro**2 == SetExpr(Interval.Ropen(1, 4))
+    assert i12ro**3 == SetExpr(Interval.Ropen(1, 8))
+
+    assert i12o + i12lo == SetExpr(Interval.open(2, 4))
+    assert i12o - i12lo == SetExpr(Interval.open(-1, 1))
+    assert i12o*i12lo == SetExpr(Interval.open(1, 4))
+    assert i12o/i12lo == SetExpr(Interval.open(S.Half, 2))
+    assert i12o + i12ro == SetExpr(Interval.open(2, 4))
+    assert i12o - i12ro == SetExpr(Interval.open(-1, 1))
+    assert i12o*i12ro == SetExpr(Interval.open(1, 4))
+    assert i12o/i12ro == SetExpr(Interval.open(S.Half, 2))
+    assert i12o + i12cc == SetExpr(Interval.open(2, 4))
+    assert i12o - i12cc == SetExpr(Interval.open(-1, 1))
+    assert i12o*i12cc == SetExpr(Interval.open(1, 4))
+    assert i12o/i12cc == SetExpr(Interval.open(S.Half, 2))
+    assert i12o**2 == SetExpr(Interval.open(1, 4))
+    assert i12o**3 == SetExpr(Interval.open(1, 8))
+
+    assert n23cc + n23cc == SetExpr(Interval(-4, 6))
+    assert n23cc - n23cc == SetExpr(Interval(-5, 5))
+    assert n23cc*n23cc == SetExpr(Interval(-6, 9))
+    assert n23cc/n23cc == SetExpr(Interval.open(-oo, oo))
+    assert n23cc + n23ro == SetExpr(Interval.Ropen(-4, 6))
+    assert n23cc - n23ro == SetExpr(Interval.Lopen(-5, 5))
+    assert n23cc*n23ro == SetExpr(Interval.Ropen(-6, 9))
+    assert n23cc/n23ro == SetExpr(Interval.Lopen(-oo, oo))
+    assert n23cc + n23lo == SetExpr(Interval.Lopen(-4, 6))
+    assert n23cc - n23lo == SetExpr(Interval.Ropen(-5, 5))
+    assert n23cc*n23lo == SetExpr(Interval(-6, 9))
+    assert n23cc/n23lo == SetExpr(Interval.open(-oo, oo))
+    assert n23cc + n23o == SetExpr(Interval.open(-4, 6))
+    assert n23cc - n23o == SetExpr(Interval.open(-5, 5))
+    assert n23cc*n23o == SetExpr(Interval.open(-6, 9))
+    assert n23cc/n23o == SetExpr(Interval.open(-oo, oo))
+    assert n23cc**2 == SetExpr(Interval(0, 9))
+    assert n23cc**3 == SetExpr(Interval(-8, 27))
+
+    n32cc = SetExpr(Interval(-3, 2))
+    n32lo = SetExpr(Interval.Lopen(-3, 2))
+    n32ro = SetExpr(Interval.Ropen(-3, 2))
+    assert n32cc*n32lo == SetExpr(Interval.Ropen(-6, 9))
+    assert n32cc*n32cc == SetExpr(Interval(-6, 9))
+    assert n32lo*n32cc == SetExpr(Interval.Ropen(-6, 9))
+    assert n32cc*n32ro == SetExpr(Interval(-6, 9))
+    assert n32lo*n32ro == SetExpr(Interval.Ropen(-6, 9))
+    assert n32cc/n32lo == SetExpr(Interval.Ropen(-oo, oo))
+    assert i12cc/n32lo == SetExpr(Interval.Ropen(-oo, oo))
+
+    assert n3n2cc**2 == SetExpr(Interval(4, 9))
+    assert n3n2cc**3 == SetExpr(Interval(-27, -8))
+
+    assert n23cc + i12cc == SetExpr(Interval(-1, 5))
+    assert n23cc - i12cc == SetExpr(Interval(-4, 2))
+    assert n23cc*i12cc == SetExpr(Interval(-4, 6))
+    assert n23cc/i12cc == SetExpr(Interval(-2, 3))
+
+
+def test_SetExpr_Intersection():
+    x, y, z, w = symbols("x y z w")
+    set1 = Interval(x, y)
+    set2 = Interval(w, z)
+    inter = Intersection(set1, set2)
+    se = SetExpr(inter)
+    assert exp(se).set == Intersection(
+        ImageSet(Lambda(x, exp(x)), set1),
+        ImageSet(Lambda(x, exp(x)), set2))
+    assert cos(se).set == ImageSet(Lambda(x, cos(x)), inter)
+
+
+def test_SetExpr_Interval_div():
+    # TODO: some expressions cannot be calculated due to bugs (currently
+    # commented):
+    assert SetExpr(Interval(-3, -2))/SetExpr(Interval(-2, 1)) == SetExpr(Interval(-oo, oo))
+    assert SetExpr(Interval(2, 3))/SetExpr(Interval(-2, 2)) == SetExpr(Interval(-oo, oo))
+
+    assert SetExpr(Interval(-3, -2))/SetExpr(Interval(0, 4)) == SetExpr(Interval(-oo, Rational(-1, 2)))
+    assert SetExpr(Interval(2, 4))/SetExpr(Interval(-3, 0)) == SetExpr(Interval(-oo, Rational(-2, 3)))
+    assert SetExpr(Interval(2, 4))/SetExpr(Interval(0, 3)) == SetExpr(Interval(Rational(2, 3), oo))
+
+    # assert SetExpr(Interval(0, 1))/SetExpr(Interval(0, 1)) == SetExpr(Interval(0, oo))
+    # assert SetExpr(Interval(-1, 0))/SetExpr(Interval(0, 1)) == SetExpr(Interval(-oo, 0))
+    assert SetExpr(Interval(-1, 2))/SetExpr(Interval(-2, 2)) == SetExpr(Interval(-oo, oo))
+
+    assert 1/SetExpr(Interval(-1, 2)) == SetExpr(Union(Interval(-oo, -1), Interval(S.Half, oo)))
+
+    assert 1/SetExpr(Interval(0, 2)) == SetExpr(Interval(S.Half, oo))
+    assert (-1)/SetExpr(Interval(0, 2)) == SetExpr(Interval(-oo, Rational(-1, 2)))
+    assert 1/SetExpr(Interval(-oo, 0)) == SetExpr(Interval.open(-oo, 0))
+    assert 1/SetExpr(Interval(-1, 0)) == SetExpr(Interval(-oo, -1))
+    # assert (-2)/SetExpr(Interval(-oo, 0)) == SetExpr(Interval(0, oo))
+    # assert 1/SetExpr(Interval(-oo, -1)) == SetExpr(Interval(-1, 0))
+
+    # assert SetExpr(Interval(1, 2))/a == Mul(SetExpr(Interval(1, 2)), 1/a, evaluate=False)
+
+    # assert SetExpr(Interval(1, 2))/0 == SetExpr(Interval(1, 2))*zoo
+    # assert SetExpr(Interval(1, oo))/oo == SetExpr(Interval(0, oo))
+    # assert SetExpr(Interval(1, oo))/(-oo) == SetExpr(Interval(-oo, 0))
+    # assert SetExpr(Interval(-oo, -1))/oo == SetExpr(Interval(-oo, 0))
+    # assert SetExpr(Interval(-oo, -1))/(-oo) == SetExpr(Interval(0, oo))
+    # assert SetExpr(Interval(-oo, oo))/oo == SetExpr(Interval(-oo, oo))
+    # assert SetExpr(Interval(-oo, oo))/(-oo) == SetExpr(Interval(-oo, oo))
+    # assert SetExpr(Interval(-1, oo))/oo == SetExpr(Interval(0, oo))
+    # assert SetExpr(Interval(-1, oo))/(-oo) == SetExpr(Interval(-oo, 0))
+    # assert SetExpr(Interval(-oo, 1))/oo == SetExpr(Interval(-oo, 0))
+    # assert SetExpr(Interval(-oo, 1))/(-oo) == SetExpr(Interval(0, oo))
+
+
+def test_SetExpr_Interval_pow():
+    assert SetExpr(Interval(0, 2))**2 == SetExpr(Interval(0, 4))
+    assert SetExpr(Interval(-1, 1))**2 == SetExpr(Interval(0, 1))
+    assert SetExpr(Interval(1, 2))**2 == SetExpr(Interval(1, 4))
+    assert SetExpr(Interval(-1, 2))**3 == SetExpr(Interval(-1, 8))
+    assert SetExpr(Interval(-1, 1))**0 == SetExpr(FiniteSet(1))
+
+
+    assert SetExpr(Interval(1, 2))**Rational(5, 2) == SetExpr(Interval(1, 4*sqrt(2)))
+    #assert SetExpr(Interval(-1, 2))**Rational(1, 3) == SetExpr(Interval(-1, 2**Rational(1, 3)))
+    #assert SetExpr(Interval(0, 2))**S.Half == SetExpr(Interval(0, sqrt(2)))
+
+    #assert SetExpr(Interval(-4, 2))**Rational(2, 3) == SetExpr(Interval(0, 2*2**Rational(1, 3)))
+
+    #assert SetExpr(Interval(-1, 5))**S.Half == SetExpr(Interval(0, sqrt(5)))
+    #assert SetExpr(Interval(-oo, 2))**S.Half == SetExpr(Interval(0, sqrt(2)))
+    #assert SetExpr(Interval(-2, 3))**(Rational(-1, 4)) == SetExpr(Interval(0, oo))
+
+    assert SetExpr(Interval(1, 5))**(-2) == SetExpr(Interval(Rational(1, 25), 1))
+    assert SetExpr(Interval(-1, 3))**(-2) == SetExpr(Interval(0, oo))
+
+    assert SetExpr(Interval(0, 2))**(-2) == SetExpr(Interval(Rational(1, 4), oo))
+    assert SetExpr(Interval(-1, 2))**(-3) == SetExpr(Union(Interval(-oo, -1), Interval(Rational(1, 8), oo)))
+    assert SetExpr(Interval(-3, -2))**(-3) == SetExpr(Interval(Rational(-1, 8), Rational(-1, 27)))
+    assert SetExpr(Interval(-3, -2))**(-2) == SetExpr(Interval(Rational(1, 9), Rational(1, 4)))
+    #assert SetExpr(Interval(0, oo))**S.Half == SetExpr(Interval(0, oo))
+    #assert SetExpr(Interval(-oo, -1))**Rational(1, 3) == SetExpr(Interval(-oo, -1))
+    #assert SetExpr(Interval(-2, 3))**(Rational(-1, 3)) == SetExpr(Interval(-oo, oo))
+
+    assert SetExpr(Interval(-oo, 0))**(-2) == SetExpr(Interval.open(0, oo))
+    assert SetExpr(Interval(-2, 0))**(-2) == SetExpr(Interval(Rational(1, 4), oo))
+
+    assert SetExpr(Interval(Rational(1, 3), S.Half))**oo == SetExpr(FiniteSet(0))
+    assert SetExpr(Interval(0, S.Half))**oo == SetExpr(FiniteSet(0))
+    assert SetExpr(Interval(S.Half, 1))**oo == SetExpr(Interval(0, oo))
+    assert SetExpr(Interval(0, 1))**oo == SetExpr(Interval(0, oo))
+    assert SetExpr(Interval(2, 3))**oo == SetExpr(FiniteSet(oo))
+    assert SetExpr(Interval(1, 2))**oo == SetExpr(Interval(0, oo))
+    assert SetExpr(Interval(S.Half, 3))**oo == SetExpr(Interval(0, oo))
+    assert SetExpr(Interval(Rational(-1, 3), Rational(-1, 4)))**oo == SetExpr(FiniteSet(0))
+    assert SetExpr(Interval(-1, Rational(-1, 2)))**oo == SetExpr(Interval(-oo, oo))
+    assert SetExpr(Interval(-3, -2))**oo == SetExpr(FiniteSet(-oo, oo))
+    assert SetExpr(Interval(-2, -1))**oo == SetExpr(Interval(-oo, oo))
+    assert SetExpr(Interval(-2, Rational(-1, 2)))**oo == SetExpr(Interval(-oo, oo))
+    assert SetExpr(Interval(Rational(-1, 2), S.Half))**oo == SetExpr(FiniteSet(0))
+    assert SetExpr(Interval(Rational(-1, 2), 1))**oo == SetExpr(Interval(0, oo))
+    assert SetExpr(Interval(Rational(-2, 3), 2))**oo == SetExpr(Interval(0, oo))
+    assert SetExpr(Interval(-1, 1))**oo == SetExpr(Interval(-oo, oo))
+    assert SetExpr(Interval(-1, S.Half))**oo == SetExpr(Interval(-oo, oo))
+    assert SetExpr(Interval(-1, 2))**oo == SetExpr(Interval(-oo, oo))
+    assert SetExpr(Interval(-2, S.Half))**oo == SetExpr(Interval(-oo, oo))
+
+    assert (SetExpr(Interval(1, 2))**x).dummy_eq(SetExpr(ImageSet(Lambda(_d, _d**x), Interval(1, 2))))
+
+    assert SetExpr(Interval(2, 3))**(-oo) == SetExpr(FiniteSet(0))
+    assert SetExpr(Interval(0, 2))**(-oo) == SetExpr(Interval(0, oo))
+    assert (SetExpr(Interval(-1, 2))**(-oo)).dummy_eq(SetExpr(ImageSet(Lambda(_d, _d**(-oo)), Interval(-1, 2))))
+
+
+def test_SetExpr_Integers():
+    assert SetExpr(S.Integers) + 1 == SetExpr(S.Integers)
+    assert (SetExpr(S.Integers) + I).dummy_eq(
+        SetExpr(ImageSet(Lambda(_d, _d + I), S.Integers)))
+    assert SetExpr(S.Integers)*(-1) == SetExpr(S.Integers)
+    assert (SetExpr(S.Integers)*2).dummy_eq(
+        SetExpr(ImageSet(Lambda(_d, 2*_d), S.Integers)))
+    assert (SetExpr(S.Integers)*I).dummy_eq(
+        SetExpr(ImageSet(Lambda(_d, I*_d), S.Integers)))
+    # issue #18050:
+    assert SetExpr(S.Integers)._eval_func(Lambda(x, I*x + 1)).dummy_eq(
+        SetExpr(ImageSet(Lambda(_d, I*_d + 1), S.Integers)))
+    # needs improvement:
+    assert (SetExpr(S.Integers)*I + 1).dummy_eq(
+        SetExpr(ImageSet(Lambda(x, x + 1),
+        ImageSet(Lambda(_d, _d*I), S.Integers))))

venv/lib/python3.10/site-packages/sympy/sets/tests/test_sets.py

@@ -0,0 +1,1704 @@
+from sympy.concrete.summations import Sum
+from sympy.core.add import Add
+from sympy.core.containers import TupleKind
+from sympy.core.function import Lambda
+from sympy.core.kind import NumberKind, UndefinedKind
+from sympy.core.numbers import (Float, I, Rational, nan, oo, pi, zoo)
+from sympy.core.power import Pow
+from sympy.core.singleton import S
+from sympy.core.symbol import (Symbol, symbols)
+from sympy.core.sympify import sympify
+from sympy.functions.elementary.miscellaneous import (Max, Min, sqrt)
+from sympy.functions.elementary.piecewise import Piecewise
+from sympy.functions.elementary.trigonometric import (cos, sin)
+from sympy.logic.boolalg import (false, true)
+from sympy.matrices.common import MatrixKind
+from sympy.matrices.dense import Matrix
+from sympy.polys.rootoftools import rootof
+from sympy.sets.contains import Contains
+from sympy.sets.fancysets import (ImageSet, Range)
+from sympy.sets.sets import (Complement, DisjointUnion, FiniteSet, Intersection, Interval, ProductSet, Set, SymmetricDifference, Union, imageset, SetKind)
+from mpmath import mpi
+
+from sympy.core.expr import unchanged
+from sympy.core.relational import Eq, Ne, Le, Lt, LessThan
+from sympy.logic import And, Or, Xor
+from sympy.testing.pytest import raises, XFAIL, warns_deprecated_sympy
+
+from sympy.abc import x, y, z, m, n
+
+EmptySet = S.EmptySet
+
+def test_imageset():
+    ints = S.Integers
+    assert imageset(x, x - 1, S.Naturals) is S.Naturals0
+    assert imageset(x, x + 1, S.Naturals0) is S.Naturals
+    assert imageset(x, abs(x), S.Naturals0) is S.Naturals0
+    assert imageset(x, abs(x), S.Naturals) is S.Naturals
+    assert imageset(x, abs(x), S.Integers) is S.Naturals0
+    # issue 16878a
+    r = symbols('r', real=True)
+    assert imageset(x, (x, x), S.Reals)._contains((1, r)) == None
+    assert imageset(x, (x, x), S.Reals)._contains((1, 2)) == False
+    assert (r, r) in imageset(x, (x, x), S.Reals)
+    assert 1 + I in imageset(x, x + I, S.Reals)
+    assert {1} not in imageset(x, (x,), S.Reals)
+    assert (1, 1) not in imageset(x, (x,), S.Reals)
+    raises(TypeError, lambda: imageset(x, ints))
+    raises(ValueError, lambda: imageset(x, y, z, ints))
+    raises(ValueError, lambda: imageset(Lambda(x, cos(x)), y))
+    assert (1, 2) in imageset(Lambda((x, y), (x, y)), ints, ints)
+    raises(ValueError, lambda: imageset(Lambda(x, x), ints, ints))
+    assert imageset(cos, ints) == ImageSet(Lambda(x, cos(x)), ints)
+    def f(x):
+        return cos(x)
+    assert imageset(f, ints) == imageset(x, cos(x), ints)
+    f = lambda x: cos(x)
+    assert imageset(f, ints) == ImageSet(Lambda(x, cos(x)), ints)
+    assert imageset(x, 1, ints) == FiniteSet(1)
+    assert imageset(x, y, ints) == {y}
+    assert imageset((x, y), (1, z), ints, S.Reals) == {(1, z)}
+    clash = Symbol('x', integer=true)
+    assert (str(imageset(lambda x: x + clash, Interval(-2, 1)).lamda.expr)
+        in ('x0 + x', 'x + x0'))
+    x1, x2 = symbols("x1, x2")
+    assert imageset(lambda x, y:
+        Add(x, y), Interval(1, 2), Interval(2, 3)).dummy_eq(
+        ImageSet(Lambda((x1, x2), x1 + x2),
+        Interval(1, 2), Interval(2, 3)))
+
+
+def test_is_empty():
+    for s in [S.Naturals, S.Naturals0, S.Integers, S.Rationals, S.Reals,
+            S.UniversalSet]:
+        assert s.is_empty is False
+
+    assert S.EmptySet.is_empty is True
+
+
+def test_is_finiteset():
+    for s in [S.Naturals, S.Naturals0, S.Integers, S.Rationals, S.Reals,
+            S.UniversalSet]:
+        assert s.is_finite_set is False
+
+    assert S.EmptySet.is_finite_set is True
+
+    assert FiniteSet(1, 2).is_finite_set is True
+    assert Interval(1, 2).is_finite_set is False
+    assert Interval(x, y).is_finite_set is None
+    assert ProductSet(FiniteSet(1), FiniteSet(2)).is_finite_set is True
+    assert ProductSet(FiniteSet(1), Interval(1, 2)).is_finite_set is False
+    assert ProductSet(FiniteSet(1), Interval(x, y)).is_finite_set is None
+    assert Union(Interval(0, 1), Interval(2, 3)).is_finite_set is False
+    assert Union(FiniteSet(1), Interval(2, 3)).is_finite_set is False
+    assert Union(FiniteSet(1), FiniteSet(2)).is_finite_set is True
+    assert Union(FiniteSet(1), Interval(x, y)).is_finite_set is None
+    assert Intersection(Interval(x, y), FiniteSet(1)).is_finite_set is True
+    assert Intersection(Interval(x, y), Interval(1, 2)).is_finite_set is None
+    assert Intersection(FiniteSet(x), FiniteSet(y)).is_finite_set is True
+    assert Complement(FiniteSet(1), Interval(x, y)).is_finite_set is True
+    assert Complement(Interval(x, y), FiniteSet(1)).is_finite_set is None
+    assert Complement(Interval(1, 2), FiniteSet(x)).is_finite_set is False
+    assert DisjointUnion(Interval(-5, 3), FiniteSet(x, y)).is_finite_set is False
+    assert DisjointUnion(S.EmptySet, FiniteSet(x, y), S.EmptySet).is_finite_set is True
+
+
+def test_deprecated_is_EmptySet():
+    with warns_deprecated_sympy():
+        S.EmptySet.is_EmptySet
+
+    with warns_deprecated_sympy():
+        FiniteSet(1).is_EmptySet
+
+
+def test_interval_arguments():
+    assert Interval(0, oo) == Interval(0, oo, False, True)
+    assert Interval(0, oo).right_open is true
+    assert Interval(-oo, 0) == Interval(-oo, 0, True, False)
+    assert Interval(-oo, 0).left_open is true
+    assert Interval(oo, -oo) == S.EmptySet
+    assert Interval(oo, oo) == S.EmptySet
+    assert Interval(-oo, -oo) == S.EmptySet
+    assert Interval(oo, x) == S.EmptySet
+    assert Interval(oo, oo) == S.EmptySet
+    assert Interval(x, -oo) == S.EmptySet
+    assert Interval(x, x) == {x}
+
+    assert isinstance(Interval(1, 1), FiniteSet)
+    e = Sum(x, (x, 1, 3))
+    assert isinstance(Interval(e, e), FiniteSet)
+
+    assert Interval(1, 0) == S.EmptySet
+    assert Interval(1, 1).measure == 0
+
+    assert Interval(1, 1, False, True) == S.EmptySet
+    assert Interval(1, 1, True, False) == S.EmptySet
+    assert Interval(1, 1, True, True) == S.EmptySet
+
+
+    assert isinstance(Interval(0, Symbol('a')), Interval)
+    assert Interval(Symbol('a', positive=True), 0) == S.EmptySet
+    raises(ValueError, lambda: Interval(0, S.ImaginaryUnit))
+    raises(ValueError, lambda: Interval(0, Symbol('z', extended_real=False)))
+    raises(ValueError, lambda: Interval(x, x + S.ImaginaryUnit))
+
+    raises(NotImplementedError, lambda: Interval(0, 1, And(x, y)))
+    raises(NotImplementedError, lambda: Interval(0, 1, False, And(x, y)))
+    raises(NotImplementedError, lambda: Interval(0, 1, z, And(x, y)))
+
+
+def test_interval_symbolic_end_points():
+    a = Symbol('a', real=True)
+
+    assert Union(Interval(0, a), Interval(0, 3)).sup == Max(a, 3)
+    assert Union(Interval(a, 0), Interval(-3, 0)).inf == Min(-3, a)
+
+    assert Interval(0, a).contains(1) == LessThan(1, a)
+
+
+def test_interval_is_empty():
+    x, y = symbols('x, y')
+    r = Symbol('r', real=True)
+    p = Symbol('p', positive=True)
+    n = Symbol('n', negative=True)
+    nn = Symbol('nn', nonnegative=True)
+    assert Interval(1, 2).is_empty == False
+    assert Interval(3, 3).is_empty == False  # FiniteSet
+    assert Interval(r, r).is_empty == False  # FiniteSet
+    assert Interval(r, r + nn).is_empty == False
+    assert Interval(x, x).is_empty == False
+    assert Interval(1, oo).is_empty == False
+    assert Interval(-oo, oo).is_empty == False
+    assert Interval(-oo, 1).is_empty == False
+    assert Interval(x, y).is_empty == None
+    assert Interval(r, oo).is_empty == False  # real implies finite
+    assert Interval(n, 0).is_empty == False
+    assert Interval(n, 0, left_open=True).is_empty == False
+    assert Interval(p, 0).is_empty == True  # EmptySet
+    assert Interval(nn, 0).is_empty == None
+    assert Interval(n, p).is_empty == False
+    assert Interval(0, p, left_open=True).is_empty == False
+    assert Interval(0, p, right_open=True).is_empty == False
+    assert Interval(0, nn, left_open=True).is_empty == None
+    assert Interval(0, nn, right_open=True).is_empty == None
+
+
+def test_union():
+    assert Union(Interval(1, 2), Interval(2, 3)) == Interval(1, 3)
+    assert Union(Interval(1, 2), Interval(2, 3, True)) == Interval(1, 3)
+    assert Union(Interval(1, 3), Interval(2, 4)) == Interval(1, 4)
+    assert Union(Interval(1, 2), Interval(1, 3)) == Interval(1, 3)
+    assert Union(Interval(1, 3), Interval(1, 2)) == Interval(1, 3)
+    assert Union(Interval(1, 3, False, True), Interval(1, 2)) == \
+        Interval(1, 3, False, True)
+    assert Union(Interval(1, 3), Interval(1, 2, False, True)) == Interval(1, 3)
+    assert Union(Interval(1, 2, True), Interval(1, 3)) == Interval(1, 3)
+    assert Union(Interval(1, 2, True), Interval(1, 3, True)) == \
+        Interval(1, 3, True)
+    assert Union(Interval(1, 2, True), Interval(1, 3, True, True)) == \
+        Interval(1, 3, True, True)
+    assert Union(Interval(1, 2, True, True), Interval(1, 3, True)) == \
+        Interval(1, 3, True)
+    assert Union(Interval(1, 3), Interval(2, 3)) == Interval(1, 3)
+    assert Union(Interval(1, 3, False, True), Interval(2, 3)) == \
+        Interval(1, 3)
+    assert Union(Interval(1, 2, False, True), Interval(2, 3, True)) != \
+        Interval(1, 3)
+    assert Union(Interval(1, 2), S.EmptySet) == Interval(1, 2)
+    assert Union(S.EmptySet) == S.EmptySet
+
+    assert Union(Interval(0, 1), *[FiniteSet(1.0/n) for n in range(1, 10)]) == \
+        Interval(0, 1)
+    # issue #18241:
+    x = Symbol('x')
+    assert Union(Interval(0, 1), FiniteSet(1, x)) == Union(
+        Interval(0, 1), FiniteSet(x))
+    assert unchanged(Union, Interval(0, 1), FiniteSet(2, x))
+
+    assert Interval(1, 2).union(Interval(2, 3)) == \
+        Interval(1, 2) + Interval(2, 3)
+
+    assert Interval(1, 2).union(Interval(2, 3)) == Interval(1, 3)
+
+    assert Union(Set()) == Set()
+
+    assert FiniteSet(1) + FiniteSet(2) + FiniteSet(3) == FiniteSet(1, 2, 3)
+    assert FiniteSet('ham') + FiniteSet('eggs') == FiniteSet('ham', 'eggs')
+    assert FiniteSet(1, 2, 3) + S.EmptySet == FiniteSet(1, 2, 3)
+
+    assert FiniteSet(1, 2, 3) & FiniteSet(2, 3, 4) == FiniteSet(2, 3)
+    assert FiniteSet(1, 2, 3) | FiniteSet(2, 3, 4) == FiniteSet(1, 2, 3, 4)
+
+    assert FiniteSet(1, 2, 3) & S.EmptySet == S.EmptySet
+    assert FiniteSet(1, 2, 3) | S.EmptySet == FiniteSet(1, 2, 3)
+
+    x = Symbol("x")
+    y = Symbol("y")
+    z = Symbol("z")
+    assert S.EmptySet | FiniteSet(x, FiniteSet(y, z)) == \
+        FiniteSet(x, FiniteSet(y, z))
+
+    # Test that Intervals and FiniteSets play nicely
+    assert Interval(1, 3) + FiniteSet(2) == Interval(1, 3)
+    assert Interval(1, 3, True, True) + FiniteSet(3) == \
+        Interval(1, 3, True, False)
+    X = Interval(1, 3) + FiniteSet(5)
+    Y = Interval(1, 2) + FiniteSet(3)
+    XandY = X.intersect(Y)
+    assert 2 in X and 3 in X and 3 in XandY
+    assert XandY.is_subset(X) and XandY.is_subset(Y)
+
+    raises(TypeError, lambda: Union(1, 2, 3))
+
+    assert X.is_iterable is False
+
+    # issue 7843
+    assert Union(S.EmptySet, FiniteSet(-sqrt(-I), sqrt(-I))) == \
+        FiniteSet(-sqrt(-I), sqrt(-I))
+
+    assert Union(S.Reals, S.Integers) == S.Reals
+
+
+def test_union_iter():
+    # Use Range because it is ordered
+    u = Union(Range(3), Range(5), Range(4), evaluate=False)
+
+    # Round robin
+    assert list(u) == [0, 0, 0, 1, 1, 1, 2, 2, 2, 3, 3, 4]
+
+
+def test_union_is_empty():
+    assert (Interval(x, y) + FiniteSet(1)).is_empty == False
+    assert (Interval(x, y) + Interval(-x, y)).is_empty == None
+
+
+def test_difference():
+    assert Interval(1, 3) - Interval(1, 2) == Interval(2, 3, True)
+    assert Interval(1, 3) - Interval(2, 3) == Interval(1, 2, False, True)
+    assert Interval(1, 3, True) - Interval(2, 3) == Interval(1, 2, True, True)
+    assert Interval(1, 3, True) - Interval(2, 3, True) == \
+        Interval(1, 2, True, False)
+    assert Interval(0, 2) - FiniteSet(1) == \
+        Union(Interval(0, 1, False, True), Interval(1, 2, True, False))
+
+    # issue #18119
+    assert S.Reals - FiniteSet(I) == S.Reals
+    assert S.Reals - FiniteSet(-I, I) == S.Reals
+    assert Interval(0, 10) - FiniteSet(-I, I) == Interval(0, 10)
+    assert Interval(0, 10) - FiniteSet(1, I) == Union(
+        Interval.Ropen(0, 1), Interval.Lopen(1, 10))
+    assert S.Reals - FiniteSet(1, 2 + I, x, y**2) == Complement(
+        Union(Interval.open(-oo, 1), Interval.open(1, oo)), FiniteSet(x, y**2),
+        evaluate=False)
+
+    assert FiniteSet(1, 2, 3) - FiniteSet(2) == FiniteSet(1, 3)
+    assert FiniteSet('ham', 'eggs') - FiniteSet('eggs') == FiniteSet('ham')
+    assert FiniteSet(1, 2, 3, 4) - Interval(2, 10, True, False) == \
+        FiniteSet(1, 2)
+    assert FiniteSet(1, 2, 3, 4) - S.EmptySet == FiniteSet(1, 2, 3, 4)
+    assert Union(Interval(0, 2), FiniteSet(2, 3, 4)) - Interval(1, 3) == \
+        Union(Interval(0, 1, False, True), FiniteSet(4))
+
+    assert -1 in S.Reals - S.Naturals
+
+
+def test_Complement():
+    A = FiniteSet(1, 3, 4)
+    B = FiniteSet(3, 4)
+    C = Interval(1, 3)
+    D = Interval(1, 2)
+
+    assert Complement(A, B, evaluate=False).is_iterable is True
+    assert Complement(A, C, evaluate=False).is_iterable is True
+    assert Complement(C, D, evaluate=False).is_iterable is None
+
+    assert FiniteSet(*Complement(A, B, evaluate=False)) == FiniteSet(1)
+    assert FiniteSet(*Complement(A, C, evaluate=False)) == FiniteSet(4)
+    raises(TypeError, lambda: FiniteSet(*Complement(C, A, evaluate=False)))
+
+    assert Complement(Interval(1, 3), Interval(1, 2)) == Interval(2, 3, True)
+    assert Complement(FiniteSet(1, 3, 4), FiniteSet(3, 4)) == FiniteSet(1)
+    assert Complement(Union(Interval(0, 2), FiniteSet(2, 3, 4)),
+                      Interval(1, 3)) == \
+        Union(Interval(0, 1, False, True), FiniteSet(4))
+
+    assert 3 not in Complement(Interval(0, 5), Interval(1, 4), evaluate=False)
+    assert -1 in Complement(S.Reals, S.Naturals, evaluate=False)
+    assert 1 not in Complement(S.Reals, S.Naturals, evaluate=False)
+
+    assert Complement(S.Integers, S.UniversalSet) == EmptySet
+    assert S.UniversalSet.complement(S.Integers) == EmptySet
+
+    assert (0 not in S.Reals.intersect(S.Integers - FiniteSet(0)))
+
+    assert S.EmptySet - S.Integers == S.EmptySet
+
+    assert (S.Integers - FiniteSet(0)) - FiniteSet(1) == S.Integers - FiniteSet(0, 1)
+
+    assert S.Reals - Union(S.Naturals, FiniteSet(pi)) == \
+            Intersection(S.Reals - S.Naturals, S.Reals - FiniteSet(pi))
+    # issue 12712
+    assert Complement(FiniteSet(x, y, 2), Interval(-10, 10)) == \
+            Complement(FiniteSet(x, y), Interval(-10, 10))
+
+    A = FiniteSet(*symbols('a:c'))
+    B = FiniteSet(*symbols('d:f'))
+    assert unchanged(Complement, ProductSet(A, A), B)
+
+    A2 = ProductSet(A, A)
+    B3 = ProductSet(B, B, B)
+    assert A2 - B3 == A2
+    assert B3 - A2 == B3
+
+
+def test_set_operations_nonsets():
+    '''Tests that e.g. FiniteSet(1) * 2 raises TypeError'''
+    ops = [
+        lambda a, b: a + b,
+        lambda a, b: a - b,
+        lambda a, b: a * b,
+        lambda a, b: a / b,
+        lambda a, b: a // b,
+        lambda a, b: a | b,
+        lambda a, b: a & b,
+        lambda a, b: a ^ b,
+        # FiniteSet(1) ** 2 gives a ProductSet
+        #lambda a, b: a ** b,
+    ]
+    Sx = FiniteSet(x)
+    Sy = FiniteSet(y)
+    sets = [
+        {1},
+        FiniteSet(1),
+        Interval(1, 2),
+        Union(Sx, Interval(1, 2)),
+        Intersection(Sx, Sy),
+        Complement(Sx, Sy),
+        ProductSet(Sx, Sy),
+        S.EmptySet,
+    ]
+    nums = [0, 1, 2, S(0), S(1), S(2)]
+
+    for si in sets:
+        for ni in nums:
+            for op in ops:
+                raises(TypeError, lambda : op(si, ni))
+                raises(TypeError, lambda : op(ni, si))
+        raises(TypeError, lambda: si ** object())
+        raises(TypeError, lambda: si ** {1})
+
+
+def test_complement():
+    assert Complement({1, 2}, {1}) == {2}
+    assert Interval(0, 1).complement(S.Reals) == \
+        Union(Interval(-oo, 0, True, True), Interval(1, oo, True, True))
+    assert Interval(0, 1, True, False).complement(S.Reals) == \
+        Union(Interval(-oo, 0, True, False), Interval(1, oo, True, True))
+    assert Interval(0, 1, False, True).complement(S.Reals) == \
+        Union(Interval(-oo, 0, True, True), Interval(1, oo, False, True))
+    assert Interval(0, 1, True, True).complement(S.Reals) == \
+        Union(Interval(-oo, 0, True, False), Interval(1, oo, False, True))
+
+    assert S.UniversalSet.complement(S.EmptySet) == S.EmptySet
+    assert S.UniversalSet.complement(S.Reals) == S.EmptySet
+    assert S.UniversalSet.complement(S.UniversalSet) == S.EmptySet
+
+    assert S.EmptySet.complement(S.Reals) == S.Reals
+
+    assert Union(Interval(0, 1), Interval(2, 3)).complement(S.Reals) == \
+        Union(Interval(-oo, 0, True, True), Interval(1, 2, True, True),
+              Interval(3, oo, True, True))
+
+    assert FiniteSet(0).complement(S.Reals) ==  \
+        Union(Interval(-oo, 0, True, True), Interval(0, oo, True, True))
+
+    assert (FiniteSet(5) + Interval(S.NegativeInfinity,
+                                    0)).complement(S.Reals) == \
+        Interval(0, 5, True, True) + Interval(5, S.Infinity, True, True)
+
+    assert FiniteSet(1, 2, 3).complement(S.Reals) == \
+        Interval(S.NegativeInfinity, 1, True, True) + \
+        Interval(1, 2, True, True) + Interval(2, 3, True, True) +\
+        Interval(3, S.Infinity, True, True)
+
+    assert FiniteSet(x).complement(S.Reals) == Complement(S.Reals, FiniteSet(x))
+
+    assert FiniteSet(0, x).complement(S.Reals) == Complement(Interval(-oo, 0, True, True) +
+                                                             Interval(0, oo, True, True)
+                                                             , FiniteSet(x), evaluate=False)
+
+    square = Interval(0, 1) * Interval(0, 1)
+    notsquare = square.complement(S.Reals*S.Reals)
+
+    assert all(pt in square for pt in [(0, 0), (.5, .5), (1, 0), (1, 1)])
+    assert not any(
+        pt in notsquare for pt in [(0, 0), (.5, .5), (1, 0), (1, 1)])
+    assert not any(pt in square for pt in [(-1, 0), (1.5, .5), (10, 10)])
+    assert all(pt in notsquare for pt in [(-1, 0), (1.5, .5), (10, 10)])
+
+
+def test_intersect1():
+    assert all(S.Integers.intersection(i) is i for i in
+        (S.Naturals, S.Naturals0))
+    assert all(i.intersection(S.Integers) is i for i in
+        (S.Naturals, S.Naturals0))
+    s =  S.Naturals0
+    assert S.Naturals.intersection(s) is S.Naturals
+    assert s.intersection(S.Naturals) is S.Naturals
+    x = Symbol('x')
+    assert Interval(0, 2).intersect(Interval(1, 2)) == Interval(1, 2)
+    assert Interval(0, 2).intersect(Interval(1, 2, True)) == \
+        Interval(1, 2, True)
+    assert Interval(0, 2, True).intersect(Interval(1, 2)) == \
+        Interval(1, 2, False, False)
+    assert Interval(0, 2, True, True).intersect(Interval(1, 2)) == \
+        Interval(1, 2, False, True)
+    assert Interval(0, 2).intersect(Union(Interval(0, 1), Interval(2, 3))) == \
+        Union(Interval(0, 1), Interval(2, 2))
+
+    assert FiniteSet(1, 2).intersect(FiniteSet(1, 2, 3)) == FiniteSet(1, 2)
+    assert FiniteSet(1, 2, x).intersect(FiniteSet(x)) == FiniteSet(x)
+    assert FiniteSet('ham', 'eggs').intersect(FiniteSet('ham')) == \
+        FiniteSet('ham')
+    assert FiniteSet(1, 2, 3, 4, 5).intersect(S.EmptySet) == S.EmptySet
+
+    assert Interval(0, 5).intersect(FiniteSet(1, 3)) == FiniteSet(1, 3)
+    assert Interval(0, 1, True, True).intersect(FiniteSet(1)) == S.EmptySet
+
+    assert Union(Interval(0, 1), Interval(2, 3)).intersect(Interval(1, 2)) == \
+        Union(Interval(1, 1), Interval(2, 2))
+    assert Union(Interval(0, 1), Interval(2, 3)).intersect(Interval(0, 2)) == \
+        Union(Interval(0, 1), Interval(2, 2))
+    assert Union(Interval(0, 1), Interval(2, 3)).intersect(Interval(1, 2, True, True)) == \
+        S.EmptySet
+    assert Union(Interval(0, 1), Interval(2, 3)).intersect(S.EmptySet) == \
+        S.EmptySet
+    assert Union(Interval(0, 5), FiniteSet('ham')).intersect(FiniteSet(2, 3, 4, 5, 6)) == \
+        Intersection(FiniteSet(2, 3, 4, 5, 6), Union(FiniteSet('ham'), Interval(0, 5)))
+    assert Intersection(FiniteSet(1, 2, 3), Interval(2, x), Interval(3, y)) == \
+        Intersection(FiniteSet(3), Interval(2, x), Interval(3, y), evaluate=False)
+    assert Intersection(FiniteSet(1, 2), Interval(0, 3), Interval(x, y)) == \
+        Intersection({1, 2}, Interval(x, y), evaluate=False)
+    assert Intersection(FiniteSet(1, 2, 4), Interval(0, 3), Interval(x, y)) == \
+        Intersection({1, 2}, Interval(x, y), evaluate=False)
+    # XXX: Is the real=True necessary here?
+    # https://github.com/sympy/sympy/issues/17532
+    m, n = symbols('m, n', real=True)
+    assert Intersection(FiniteSet(m), FiniteSet(m, n), Interval(m, m+1)) == \
+        FiniteSet(m)
+
+    # issue 8217
+    assert Intersection(FiniteSet(x), FiniteSet(y)) == \
+        Intersection(FiniteSet(x), FiniteSet(y), evaluate=False)
+    assert FiniteSet(x).intersect(S.Reals) == \
+        Intersection(S.Reals, FiniteSet(x), evaluate=False)
+
+    # tests for the intersection alias
+    assert Interval(0, 5).intersection(FiniteSet(1, 3)) == FiniteSet(1, 3)
+    assert Interval(0, 1, True, True).intersection(FiniteSet(1)) == S.EmptySet
+
+    assert Union(Interval(0, 1), Interval(2, 3)).intersection(Interval(1, 2)) == \
+        Union(Interval(1, 1), Interval(2, 2))
+
+
+def test_intersection():
+    # iterable
+    i = Intersection(FiniteSet(1, 2, 3), Interval(2, 5), evaluate=False)
+    assert i.is_iterable
+    assert set(i) == {S(2), S(3)}
+
+    # challenging intervals
+    x = Symbol('x', real=True)
+    i = Intersection(Interval(0, 3), Interval(x, 6))
+    assert (5 in i) is False
+    raises(TypeError, lambda: 2 in i)
+
+    # Singleton special cases
+    assert Intersection(Interval(0, 1), S.EmptySet) == S.EmptySet
+    assert Intersection(Interval(-oo, oo), Interval(-oo, x)) == Interval(-oo, x)
+
+    # Products
+    line = Interval(0, 5)
+    i = Intersection(line**2, line**3, evaluate=False)
+    assert (2, 2) not in i
+    assert (2, 2, 2) not in i
+    raises(TypeError, lambda: list(i))
+
+    a = Intersection(Intersection(S.Integers, S.Naturals, evaluate=False), S.Reals, evaluate=False)
+    assert a._argset == frozenset([Intersection(S.Naturals, S.Integers, evaluate=False), S.Reals])
+
+    assert Intersection(S.Complexes, FiniteSet(S.ComplexInfinity)) == S.EmptySet
+
+    # issue 12178
+    assert Intersection() == S.UniversalSet
+
+    # issue 16987
+    assert Intersection({1}, {1}, {x}) == Intersection({1}, {x})
+
+
+def test_issue_9623():
+    n = Symbol('n')
+
+    a = S.Reals
+    b = Interval(0, oo)
+    c = FiniteSet(n)
+
+    assert Intersection(a, b, c) == Intersection(b, c)
+    assert Intersection(Interval(1, 2), Interval(3, 4), FiniteSet(n)) == EmptySet
+
+
+def test_is_disjoint():
+    assert Interval(0, 2).is_disjoint(Interval(1, 2)) == False
+    assert Interval(0, 2).is_disjoint(Interval(3, 4)) == True
+
+
+def test_ProductSet__len__():
+    A = FiniteSet(1, 2)
+    B = FiniteSet(1, 2, 3)
+    assert ProductSet(A).__len__() == 2
+    assert ProductSet(A).__len__() is not S(2)
+    assert ProductSet(A, B).__len__() == 6
+    assert ProductSet(A, B).__len__() is not S(6)
+
+
+def test_ProductSet():
+    # ProductSet is always a set of Tuples
+    assert ProductSet(S.Reals) == S.Reals ** 1
+    assert ProductSet(S.Reals, S.Reals) == S.Reals ** 2
+    assert ProductSet(S.Reals, S.Reals, S.Reals) == S.Reals ** 3
+
+    assert ProductSet(S.Reals) != S.Reals
+    assert ProductSet(S.Reals, S.Reals) == S.Reals * S.Reals
+    assert ProductSet(S.Reals, S.Reals, S.Reals) != S.Reals * S.Reals * S.Reals
+    assert ProductSet(S.Reals, S.Reals, S.Reals) == (S.Reals * S.Reals * S.Reals).flatten()
+
+    assert 1 not in ProductSet(S.Reals)
+    assert (1,) in ProductSet(S.Reals)
+
+    assert 1 not in ProductSet(S.Reals, S.Reals)
+    assert (1, 2) in ProductSet(S.Reals, S.Reals)
+    assert (1, I) not in ProductSet(S.Reals, S.Reals)
+
+    assert (1, 2, 3) in ProductSet(S.Reals, S.Reals, S.Reals)
+    assert (1, 2, 3) in S.Reals ** 3
+    assert (1, 2, 3) not in S.Reals * S.Reals * S.Reals
+    assert ((1, 2), 3) in S.Reals * S.Reals * S.Reals
+    assert (1, (2, 3)) not in S.Reals * S.Reals * S.Reals
+    assert (1, (2, 3)) in S.Reals * (S.Reals * S.Reals)
+
+    assert ProductSet() == FiniteSet(())
+    assert ProductSet(S.Reals, S.EmptySet) == S.EmptySet
+
+    # See GH-17458
+
+    for ni in range(5):
+        Rn = ProductSet(*(S.Reals,) * ni)
+        assert (1,) * ni in Rn
+        assert 1 not in Rn
+
+    assert (S.Reals * S.Reals) * S.Reals != S.Reals * (S.Reals * S.Reals)
+
+    S1 = S.Reals
+    S2 = S.Integers
+    x1 = pi
+    x2 = 3
+    assert x1 in S1
+    assert x2 in S2
+    assert (x1, x2) in S1 * S2
+    S3 = S1 * S2
+    x3 = (x1, x2)
+    assert x3 in S3
+    assert (x3, x3) in S3 * S3
+    assert x3 + x3 not in S3 * S3
+
+    raises(ValueError, lambda: S.Reals**-1)
+    with warns_deprecated_sympy():
+        ProductSet(FiniteSet(s) for s in range(2))
+    raises(TypeError, lambda: ProductSet(None))
+
+    S1 = FiniteSet(1, 2)
+    S2 = FiniteSet(3, 4)
+    S3 = ProductSet(S1, S2)
+    assert (S3.as_relational(x, y)
+            == And(S1.as_relational(x), S2.as_relational(y))
+            == And(Or(Eq(x, 1), Eq(x, 2)), Or(Eq(y, 3), Eq(y, 4))))
+    raises(ValueError, lambda: S3.as_relational(x))
+    raises(ValueError, lambda: S3.as_relational(x, 1))
+    raises(ValueError, lambda: ProductSet(Interval(0, 1)).as_relational(x, y))
+
+    Z2 = ProductSet(S.Integers, S.Integers)
+    assert Z2.contains((1, 2)) is S.true
+    assert Z2.contains((1,)) is S.false
+    assert Z2.contains(x) == Contains(x, Z2, evaluate=False)
+    assert Z2.contains(x).subs(x, 1) is S.false
+    assert Z2.contains((x, 1)).subs(x, 2) is S.true
+    assert Z2.contains((x, y)) == Contains((x, y), Z2, evaluate=False)
+    assert unchanged(Contains, (x, y), Z2)
+    assert Contains((1, 2), Z2) is S.true
+
+
+def test_ProductSet_of_single_arg_is_not_arg():
+    assert unchanged(ProductSet, Interval(0, 1))
+    assert unchanged(ProductSet, ProductSet(Interval(0, 1)))
+
+
+def test_ProductSet_is_empty():
+    assert ProductSet(S.Integers, S.Reals).is_empty == False
+    assert ProductSet(Interval(x, 1), S.Reals).is_empty == None
+
+
+def test_interval_subs():
+    a = Symbol('a', real=True)
+
+    assert Interval(0, a).subs(a, 2) == Interval(0, 2)
+    assert Interval(a, 0).subs(a, 2) == S.EmptySet
+
+
+def test_interval_to_mpi():
+    assert Interval(0, 1).to_mpi() == mpi(0, 1)
+    assert Interval(0, 1, True, False).to_mpi() == mpi(0, 1)
+    assert type(Interval(0, 1).to_mpi()) == type(mpi(0, 1))
+
+
+def test_set_evalf():
+    assert Interval(S(11)/64, S.Half).evalf() == Interval(
+        Float('0.171875'), Float('0.5'))
+    assert Interval(x, S.Half, right_open=True).evalf() == Interval(
+        x, Float('0.5'), right_open=True)
+    assert Interval(-oo, S.Half).evalf() == Interval(-oo, Float('0.5'))
+    assert FiniteSet(2, x).evalf() == FiniteSet(Float('2.0'), x)
+
+
+def test_measure():
+    a = Symbol('a', real=True)
+
+    assert Interval(1, 3).measure == 2
+    assert Interval(0, a).measure == a
+    assert Interval(1, a).measure == a - 1
+
+    assert Union(Interval(1, 2), Interval(3, 4)).measure == 2
+    assert Union(Interval(1, 2), Interval(3, 4), FiniteSet(5, 6, 7)).measure \
+        == 2
+
+    assert FiniteSet(1, 2, oo, a, -oo, -5).measure == 0
+
+    assert S.EmptySet.measure == 0
+
+    square = Interval(0, 10) * Interval(0, 10)
+    offsetsquare = Interval(5, 15) * Interval(5, 15)
+    band = Interval(-oo, oo) * Interval(2, 4)
+
+    assert square.measure == offsetsquare.measure == 100
+    assert (square + offsetsquare).measure == 175  # there is some overlap
+    assert (square - offsetsquare).measure == 75
+    assert (square * FiniteSet(1, 2, 3)).measure == 0
+    assert (square.intersect(band)).measure == 20
+    assert (square + band).measure is oo
+    assert (band * FiniteSet(1, 2, 3)).measure is nan
+
+
+def test_is_subset():
+    assert Interval(0, 1).is_subset(Interval(0, 2)) is True
+    assert Interval(0, 3).is_subset(Interval(0, 2)) is False
+    assert Interval(0, 1).is_subset(FiniteSet(0, 1)) is False
+
+    assert FiniteSet(1, 2).is_subset(FiniteSet(1, 2, 3, 4))
+    assert FiniteSet(4, 5).is_subset(FiniteSet(1, 2, 3, 4)) is False
+    assert FiniteSet(1).is_subset(Interval(0, 2))
+    assert FiniteSet(1, 2).is_subset(Interval(0, 2, True, True)) is False
+    assert (Interval(1, 2) + FiniteSet(3)).is_subset(
+        Interval(0, 2, False, True) + FiniteSet(2, 3))
+
+    assert Interval(3, 4).is_subset(Union(Interval(0, 1), Interval(2, 5))) is True
+    assert Interval(3, 6).is_subset(Union(Interval(0, 1), Interval(2, 5))) is False
+
+    assert FiniteSet(1, 2, 3, 4).is_subset(Interval(0, 5)) is True
+    assert S.EmptySet.is_subset(FiniteSet(1, 2, 3)) is True
+
+    assert Interval(0, 1).is_subset(S.EmptySet) is False
+    assert S.EmptySet.is_subset(S.EmptySet) is True
+
+    raises(ValueError, lambda: S.EmptySet.is_subset(1))
+
+    # tests for the issubset alias
+    assert FiniteSet(1, 2, 3, 4).issubset(Interval(0, 5)) is True
+    assert S.EmptySet.issubset(FiniteSet(1, 2, 3)) is True
+
+    assert S.Naturals.is_subset(S.Integers)
+    assert S.Naturals0.is_subset(S.Integers)
+
+    assert FiniteSet(x).is_subset(FiniteSet(y)) is None
+    assert FiniteSet(x).is_subset(FiniteSet(y).subs(y, x)) is True
+    assert FiniteSet(x).is_subset(FiniteSet(y).subs(y, x+1)) is False
+
+    assert Interval(0, 1).is_subset(Interval(0, 1, left_open=True)) is False
+    assert Interval(-2, 3).is_subset(Union(Interval(-oo, -2), Interval(3, oo))) is False
+
+    n = Symbol('n', integer=True)
+    assert Range(-3, 4, 1).is_subset(FiniteSet(-10, 10)) is False
+    assert Range(S(10)**100).is_subset(FiniteSet(0, 1, 2)) is False
+    assert Range(6, 0, -2).is_subset(FiniteSet(2, 4, 6)) is True
+    assert Range(1, oo).is_subset(FiniteSet(1, 2)) is False
+    assert Range(-oo, 1).is_subset(FiniteSet(1)) is False
+    assert Range(3).is_subset(FiniteSet(0, 1, n)) is None
+    assert Range(n, n + 2).is_subset(FiniteSet(n, n + 1)) is True
+    assert Range(5).is_subset(Interval(0, 4, right_open=True)) is False
+    #issue 19513
+    assert imageset(Lambda(n, 1/n), S.Integers).is_subset(S.Reals) is None
+
+def test_is_proper_subset():
+    assert Interval(0, 1).is_proper_subset(Interval(0, 2)) is True
+    assert Interval(0, 3).is_proper_subset(Interval(0, 2)) is False
+    assert S.EmptySet.is_proper_subset(FiniteSet(1, 2, 3)) is True
+
+    raises(ValueError, lambda: Interval(0, 1).is_proper_subset(0))
+
+
+def test_is_superset():
+    assert Interval(0, 1).is_superset(Interval(0, 2)) == False
+    assert Interval(0, 3).is_superset(Interval(0, 2))
+
+    assert FiniteSet(1, 2).is_superset(FiniteSet(1, 2, 3, 4)) == False
+    assert FiniteSet(4, 5).is_superset(FiniteSet(1, 2, 3, 4)) == False
+    assert FiniteSet(1).is_superset(Interval(0, 2)) == False
+    assert FiniteSet(1, 2).is_superset(Interval(0, 2, True, True)) == False
+    assert (Interval(1, 2) + FiniteSet(3)).is_superset(
+        Interval(0, 2, False, True) + FiniteSet(2, 3)) == False
+
+    assert Interval(3, 4).is_superset(Union(Interval(0, 1), Interval(2, 5))) == False
+
+    assert FiniteSet(1, 2, 3, 4).is_superset(Interval(0, 5)) == False
+    assert S.EmptySet.is_superset(FiniteSet(1, 2, 3)) == False
+
+    assert Interval(0, 1).is_superset(S.EmptySet) == True
+    assert S.EmptySet.is_superset(S.EmptySet) == True
+
+    raises(ValueError, lambda: S.EmptySet.is_superset(1))
+
+    # tests for the issuperset alias
+    assert Interval(0, 1).issuperset(S.EmptySet) == True
+    assert S.EmptySet.issuperset(S.EmptySet) == True
+
+
+def test_is_proper_superset():
+    assert Interval(0, 1).is_proper_superset(Interval(0, 2)) is False
+    assert Interval(0, 3).is_proper_superset(Interval(0, 2)) is True
+    assert FiniteSet(1, 2, 3).is_proper_superset(S.EmptySet) is True
+
+    raises(ValueError, lambda: Interval(0, 1).is_proper_superset(0))
+
+
+def test_contains():
+    assert Interval(0, 2).contains(1) is S.true
+    assert Interval(0, 2).contains(3) is S.false
+    assert Interval(0, 2, True, False).contains(0) is S.false
+    assert Interval(0, 2, True, False).contains(2) is S.true
+    assert Interval(0, 2, False, True).contains(0) is S.true
+    assert Interval(0, 2, False, True).contains(2) is S.false
+    assert Interval(0, 2, True, True).contains(0) is S.false
+    assert Interval(0, 2, True, True).contains(2) is S.false
+
+    assert (Interval(0, 2) in Interval(0, 2)) is False
+
+    assert FiniteSet(1, 2, 3).contains(2) is S.true
+    assert FiniteSet(1, 2, Symbol('x')).contains(Symbol('x')) is S.true
+
+    assert FiniteSet(y)._contains(x) is None
+    raises(TypeError, lambda: x in FiniteSet(y))
+    assert FiniteSet({x, y})._contains({x}) is None
+    assert FiniteSet({x, y}).subs(y, x)._contains({x}) is True
+    assert FiniteSet({x, y}).subs(y, x+1)._contains({x}) is False
+
+    # issue 8197
+    from sympy.abc import a, b
+    assert isinstance(FiniteSet(b).contains(-a), Contains)
+    assert isinstance(FiniteSet(b).contains(a), Contains)
+    assert isinstance(FiniteSet(a).contains(1), Contains)
+    raises(TypeError, lambda: 1 in FiniteSet(a))
+
+    # issue 8209
+    rad1 = Pow(Pow(2, Rational(1, 3)) - 1, Rational(1, 3))
+    rad2 = Pow(Rational(1, 9), Rational(1, 3)) - Pow(Rational(2, 9), Rational(1, 3)) + Pow(Rational(4, 9), Rational(1, 3))
+    s1 = FiniteSet(rad1)
+    s2 = FiniteSet(rad2)
+    assert s1 - s2 == S.EmptySet
+
+    items = [1, 2, S.Infinity, S('ham'), -1.1]
+    fset = FiniteSet(*items)
+    assert all(item in fset for item in items)
+    assert all(fset.contains(item) is S.true for item in items)
+
+    assert Union(Interval(0, 1), Interval(2, 5)).contains(3) is S.true
+    assert Union(Interval(0, 1), Interval(2, 5)).contains(6) is S.false
+    assert Union(Interval(0, 1), FiniteSet(2, 5)).contains(3) is S.false
+
+    assert S.EmptySet.contains(1) is S.false
+    assert FiniteSet(rootof(x**3 + x - 1, 0)).contains(S.Infinity) is S.false
+
+    assert rootof(x**5 + x**3 + 1, 0) in S.Reals
+    assert not rootof(x**5 + x**3 + 1, 1) in S.Reals
+
+    # non-bool results
+    assert Union(Interval(1, 2), Interval(3, 4)).contains(x) == \
+        Or(And(S.One <= x, x <= 2), And(S(3) <= x, x <= 4))
+    assert Intersection(Interval(1, x), Interval(2, 3)).contains(y) == \
+        And(y <= 3, y <= x, S.One <= y, S(2) <= y)
+
+    assert (S.Complexes).contains(S.ComplexInfinity) == S.false
+
+
+def test_interval_symbolic():
+    x = Symbol('x')
+    e = Interval(0, 1)
+    assert e.contains(x) == And(S.Zero <= x, x <= 1)
+    raises(TypeError, lambda: x in e)
+    e = Interval(0, 1, True, True)
+    assert e.contains(x) == And(S.Zero < x, x < 1)
+    c = Symbol('c', real=False)
+    assert Interval(x, x + 1).contains(c) == False
+    e = Symbol('e', extended_real=True)
+    assert Interval(-oo, oo).contains(e) == And(
+        S.NegativeInfinity < e, e < S.Infinity)
+
+
+def test_union_contains():
+    x = Symbol('x')
+    i1 = Interval(0, 1)
+    i2 = Interval(2, 3)
+    i3 = Union(i1, i2)
+    assert i3.as_relational(x) == Or(And(S.Zero <= x, x <= 1), And(S(2) <= x, x <= 3))
+    raises(TypeError, lambda: x in i3)
+    e = i3.contains(x)
+    assert e == i3.as_relational(x)
+    assert e.subs(x, -0.5) is false
+    assert e.subs(x, 0.5) is true
+    assert e.subs(x, 1.5) is false
+    assert e.subs(x, 2.5) is true
+    assert e.subs(x, 3.5) is false
+
+    U = Interval(0, 2, True, True) + Interval(10, oo) + FiniteSet(-1, 2, 5, 6)
+    assert all(el not in U for el in [0, 4, -oo])
+    assert all(el in U for el in [2, 5, 10])
+
+
+def test_is_number():
+    assert Interval(0, 1).is_number is False
+    assert Set().is_number is False
+
+
+def test_Interval_is_left_unbounded():
+    assert Interval(3, 4).is_left_unbounded is False
+    assert Interval(-oo, 3).is_left_unbounded is True
+    assert Interval(Float("-inf"), 3).is_left_unbounded is True
+
+
+def test_Interval_is_right_unbounded():
+    assert Interval(3, 4).is_right_unbounded is False
+    assert Interval(3, oo).is_right_unbounded is True
+    assert Interval(3, Float("+inf")).is_right_unbounded is True
+
+
+def test_Interval_as_relational():
+    x = Symbol('x')
+
+    assert Interval(-1, 2, False, False).as_relational(x) == \
+        And(Le(-1, x), Le(x, 2))
+    assert Interval(-1, 2, True, False).as_relational(x) == \
+        And(Lt(-1, x), Le(x, 2))
+    assert Interval(-1, 2, False, True).as_relational(x) == \
+        And(Le(-1, x), Lt(x, 2))
+    assert Interval(-1, 2, True, True).as_relational(x) == \
+        And(Lt(-1, x), Lt(x, 2))
+
+    assert Interval(-oo, 2, right_open=False).as_relational(x) == And(Lt(-oo, x), Le(x, 2))
+    assert Interval(-oo, 2, right_open=True).as_relational(x) == And(Lt(-oo, x), Lt(x, 2))
+
+    assert Interval(-2, oo, left_open=False).as_relational(x) == And(Le(-2, x), Lt(x, oo))
+    assert Interval(-2, oo, left_open=True).as_relational(x) == And(Lt(-2, x), Lt(x, oo))
+
+    assert Interval(-oo, oo).as_relational(x) == And(Lt(-oo, x), Lt(x, oo))
+    x = Symbol('x', real=True)
+    y = Symbol('y', real=True)
+    assert Interval(x, y).as_relational(x) == (x <= y)
+    assert Interval(y, x).as_relational(x) == (y <= x)
+
+
+def test_Finite_as_relational():
+    x = Symbol('x')
+    y = Symbol('y')
+
+    assert FiniteSet(1, 2).as_relational(x) == Or(Eq(x, 1), Eq(x, 2))
+    assert FiniteSet(y, -5).as_relational(x) == Or(Eq(x, y), Eq(x, -5))
+
+
+def test_Union_as_relational():
+    x = Symbol('x')
+    assert (Interval(0, 1) + FiniteSet(2)).as_relational(x) == \
+        Or(And(Le(0, x), Le(x, 1)), Eq(x, 2))
+    assert (Interval(0, 1, True, True) + FiniteSet(1)).as_relational(x) == \
+        And(Lt(0, x), Le(x, 1))
+    assert Or(x < 0, x > 0).as_set().as_relational(x) == \
+        And((x > -oo), (x < oo), Ne(x, 0))
+    assert (Interval.Ropen(1, 3) + Interval.Lopen(3, 5)
+        ).as_relational(x) == And(Ne(x,3),(x>=1),(x<=5))
+
+
+def test_Intersection_as_relational():
+    x = Symbol('x')
+    assert (Intersection(Interval(0, 1), FiniteSet(2),
+            evaluate=False).as_relational(x)
+            == And(And(Le(0, x), Le(x, 1)), Eq(x, 2)))
+
+
+def test_Complement_as_relational():
+    x = Symbol('x')
+    expr = Complement(Interval(0, 1), FiniteSet(2), evaluate=False)
+    assert expr.as_relational(x) == \
+        And(Le(0, x), Le(x, 1), Ne(x, 2))
+
+
+@XFAIL
+def test_Complement_as_relational_fail():
+    x = Symbol('x')
+    expr = Complement(Interval(0, 1), FiniteSet(2), evaluate=False)
+    # XXX This example fails because 0 <= x changes to x >= 0
+    # during the evaluation.
+    assert expr.as_relational(x) == \
+            (0 <= x) & (x <= 1) & Ne(x, 2)
+
+
+def test_SymmetricDifference_as_relational():
+    x = Symbol('x')
+    expr = SymmetricDifference(Interval(0, 1), FiniteSet(2), evaluate=False)
+    assert expr.as_relational(x) == Xor(Eq(x, 2), Le(0, x) & Le(x, 1))
+
+
+def test_EmptySet():
+    assert S.EmptySet.as_relational(Symbol('x')) is S.false
+    assert S.EmptySet.intersect(S.UniversalSet) == S.EmptySet
+    assert S.EmptySet.boundary == S.EmptySet
+
+
+def test_finite_basic():
+    x = Symbol('x')
+    A = FiniteSet(1, 2, 3)
+    B = FiniteSet(3, 4, 5)
+    AorB = Union(A, B)
+    AandB = A.intersect(B)
+    assert A.is_subset(AorB) and B.is_subset(AorB)
+    assert AandB.is_subset(A)
+    assert AandB == FiniteSet(3)
+
+    assert A.inf == 1 and A.sup == 3
+    assert AorB.inf == 1 and AorB.sup == 5
+    assert FiniteSet(x, 1, 5).sup == Max(x, 5)
+    assert FiniteSet(x, 1, 5).inf == Min(x, 1)
+
+    # issue 7335
+    assert FiniteSet(S.EmptySet) != S.EmptySet
+    assert FiniteSet(FiniteSet(1, 2, 3)) != FiniteSet(1, 2, 3)
+    assert FiniteSet((1, 2, 3)) != FiniteSet(1, 2, 3)
+
+    # Ensure a variety of types can exist in a FiniteSet
+    assert FiniteSet((1, 2), A, -5, x, 'eggs', x**2)
+
+    assert (A > B) is False
+    assert (A >= B) is False
+    assert (A < B) is False
+    assert (A <= B) is False
+    assert AorB > A and AorB > B
+    assert AorB >= A and AorB >= B
+    assert A >= A and A <= A
+    assert A >= AandB and B >= AandB
+    assert A > AandB and B > AandB
+
+
+def test_product_basic():
+    H, T = 'H', 'T'
+    unit_line = Interval(0, 1)
+    d6 = FiniteSet(1, 2, 3, 4, 5, 6)
+    d4 = FiniteSet(1, 2, 3, 4)
+    coin = FiniteSet(H, T)
+
+    square = unit_line * unit_line
+
+    assert (0, 0) in square
+    assert 0 not in square
+    assert (H, T) in coin ** 2
+    assert (.5, .5, .5) in (square * unit_line).flatten()
+    assert ((.5, .5), .5) in square * unit_line
+    assert (H, 3, 3) in (coin * d6 * d6).flatten()
+    assert ((H, 3), 3) in coin * d6 * d6
+    HH, TT = sympify(H), sympify(T)
+    assert set(coin**2) == {(HH, HH), (HH, TT), (TT, HH), (TT, TT)}
+
+    assert (d4*d4).is_subset(d6*d6)
+
+    assert square.complement(Interval(-oo, oo)*Interval(-oo, oo)) == Union(
+        (Interval(-oo, 0, True, True) +
+         Interval(1, oo, True, True))*Interval(-oo, oo),
+         Interval(-oo, oo)*(Interval(-oo, 0, True, True) +
+                  Interval(1, oo, True, True)))
+
+    assert (Interval(-5, 5)**3).is_subset(Interval(-10, 10)**3)
+    assert not (Interval(-10, 10)**3).is_subset(Interval(-5, 5)**3)
+    assert not (Interval(-5, 5)**2).is_subset(Interval(-10, 10)**3)
+
+    assert (Interval(.2, .5)*FiniteSet(.5)).is_subset(square)  # segment in square
+
+    assert len(coin*coin*coin) == 8
+    assert len(S.EmptySet*S.EmptySet) == 0
+    assert len(S.EmptySet*coin) == 0
+    raises(TypeError, lambda: len(coin*Interval(0, 2)))
+
+
+def test_real():
+    x = Symbol('x', real=True)
+
+    I = Interval(0, 5)
+    J = Interval(10, 20)
+    A = FiniteSet(1, 2, 30, x, S.Pi)
+    B = FiniteSet(-4, 0)
+    C = FiniteSet(100)
+    D = FiniteSet('Ham', 'Eggs')
+
+    assert all(s.is_subset(S.Reals) for s in [I, J, A, B, C])
+    assert not D.is_subset(S.Reals)
+    assert all((a + b).is_subset(S.Reals) for a in [I, J, A, B, C] for b in [I, J, A, B, C])
+    assert not any((a + D).is_subset(S.Reals) for a in [I, J, A, B, C, D])
+
+    assert not (I + A + D).is_subset(S.Reals)
+
+
+def test_supinf():
+    x = Symbol('x', real=True)
+    y = Symbol('y', real=True)
+
+    assert (Interval(0, 1) + FiniteSet(2)).sup == 2
+    assert (Interval(0, 1) + FiniteSet(2)).inf == 0
+    assert (Interval(0, 1) + FiniteSet(x)).sup == Max(1, x)
+    assert (Interval(0, 1) + FiniteSet(x)).inf == Min(0, x)
+    assert FiniteSet(5, 1, x).sup == Max(5, x)
+    assert FiniteSet(5, 1, x).inf == Min(1, x)
+    assert FiniteSet(5, 1, x, y).sup == Max(5, x, y)
+    assert FiniteSet(5, 1, x, y).inf == Min(1, x, y)
+    assert FiniteSet(5, 1, x, y, S.Infinity, S.NegativeInfinity).sup == \
+        S.Infinity
+    assert FiniteSet(5, 1, x, y, S.Infinity, S.NegativeInfinity).inf == \
+        S.NegativeInfinity
+    assert FiniteSet('Ham', 'Eggs').sup == Max('Ham', 'Eggs')
+
+
+def test_universalset():
+    U = S.UniversalSet
+    x = Symbol('x')
+    assert U.as_relational(x) is S.true
+    assert U.union(Interval(2, 4)) == U
+
+    assert U.intersect(Interval(2, 4)) == Interval(2, 4)
+    assert U.measure is S.Infinity
+    assert U.boundary == S.EmptySet
+    assert U.contains(0) is S.true
+
+
+def test_Union_of_ProductSets_shares():
+    line = Interval(0, 2)
+    points = FiniteSet(0, 1, 2)
+    assert Union(line * line, line * points) == line * line
+
+
+def test_Interval_free_symbols():
+    # issue 6211
+    assert Interval(0, 1).free_symbols == set()
+    x = Symbol('x', real=True)
+    assert Interval(0, x).free_symbols == {x}
+
+
+def test_image_interval():
+    x = Symbol('x', real=True)
+    a = Symbol('a', real=True)
+    assert imageset(x, 2*x, Interval(-2, 1)) == Interval(-4, 2)
+    assert imageset(x, 2*x, Interval(-2, 1, True, False)) == \
+        Interval(-4, 2, True, False)
+    assert imageset(x, x**2, Interval(-2, 1, True, False)) == \
+        Interval(0, 4, False, True)
+    assert imageset(x, x**2, Interval(-2, 1)) == Interval(0, 4)
+    assert imageset(x, x**2, Interval(-2, 1, True, False)) == \
+        Interval(0, 4, False, True)
+    assert imageset(x, x**2, Interval(-2, 1, True, True)) == \
+        Interval(0, 4, False, True)
+    assert imageset(x, (x - 2)**2, Interval(1, 3)) == Interval(0, 1)
+    assert imageset(x, 3*x**4 - 26*x**3 + 78*x**2 - 90*x, Interval(0, 4)) == \
+        Interval(-35, 0)  # Multiple Maxima
+    assert imageset(x, x + 1/x, Interval(-oo, oo)) == Interval(-oo, -2) \
+        + Interval(2, oo)  # Single Infinite discontinuity
+    assert imageset(x, 1/x + 1/(x-1)**2, Interval(0, 2, True, False)) == \
+        Interval(Rational(3, 2), oo, False)  # Multiple Infinite discontinuities
+
+    # Test for Python lambda
+    assert imageset(lambda x: 2*x, Interval(-2, 1)) == Interval(-4, 2)
+
+    assert imageset(Lambda(x, a*x), Interval(0, 1)) == \
+            ImageSet(Lambda(x, a*x), Interval(0, 1))
+
+    assert imageset(Lambda(x, sin(cos(x))), Interval(0, 1)) == \
+            ImageSet(Lambda(x, sin(cos(x))), Interval(0, 1))
+
+
+def test_image_piecewise():
+    f = Piecewise((x, x <= -1), (1/x**2, x <= 5), (x**3, True))
+    f1 = Piecewise((0, x <= 1), (1, x <= 2), (2, True))
+    assert imageset(x, f, Interval(-5, 5)) == Union(Interval(-5, -1), Interval(Rational(1, 25), oo))
+    assert imageset(x, f1, Interval(1, 2)) == FiniteSet(0, 1)
+
+
+@XFAIL  # See: https://github.com/sympy/sympy/pull/2723#discussion_r8659826
+def test_image_Intersection():
+    x = Symbol('x', real=True)
+    y = Symbol('y', real=True)
+    assert imageset(x, x**2, Interval(-2, 0).intersect(Interval(x, y))) == \
+           Interval(0, 4).intersect(Interval(Min(x**2, y**2), Max(x**2, y**2)))
+
+
+def test_image_FiniteSet():
+    x = Symbol('x', real=True)
+    assert imageset(x, 2*x, FiniteSet(1, 2, 3)) == FiniteSet(2, 4, 6)
+
+
+def test_image_Union():
+    x = Symbol('x', real=True)
+    assert imageset(x, x**2, Interval(-2, 0) + FiniteSet(1, 2, 3)) == \
+            (Interval(0, 4) + FiniteSet(9))
+
+
+def test_image_EmptySet():
+    x = Symbol('x', real=True)
+    assert imageset(x, 2*x, S.EmptySet) == S.EmptySet
+
+
+def test_issue_5724_7680():
+    assert I not in S.Reals  # issue 7680
+    assert Interval(-oo, oo).contains(I) is S.false
+
+
+def test_boundary():
+    assert FiniteSet(1).boundary == FiniteSet(1)
+    assert all(Interval(0, 1, left_open, right_open).boundary == FiniteSet(0, 1)
+            for left_open in (true, false) for right_open in (true, false))
+
+
+def test_boundary_Union():
+    assert (Interval(0, 1) + Interval(2, 3)).boundary == FiniteSet(0, 1, 2, 3)
+    assert ((Interval(0, 1, False, True)
+           + Interval(1, 2, True, False)).boundary == FiniteSet(0, 1, 2))
+
+    assert (Interval(0, 1) + FiniteSet(2)).boundary == FiniteSet(0, 1, 2)
+    assert Union(Interval(0, 10), Interval(5, 15), evaluate=False).boundary \
+            == FiniteSet(0, 15)
+
+    assert Union(Interval(0, 10), Interval(0, 1), evaluate=False).boundary \
+            == FiniteSet(0, 10)
+    assert Union(Interval(0, 10, True, True),
+                 Interval(10, 15, True, True), evaluate=False).boundary \
+            == FiniteSet(0, 10, 15)
+
+
+@XFAIL
+def test_union_boundary_of_joining_sets():
+    """ Testing the boundary of unions is a hard problem """
+    assert Union(Interval(0, 10), Interval(10, 15), evaluate=False).boundary \
+            == FiniteSet(0, 15)
+
+
+def test_boundary_ProductSet():
+    open_square = Interval(0, 1, True, True) ** 2
+    assert open_square.boundary == (FiniteSet(0, 1) * Interval(0, 1)
+                                  + Interval(0, 1) * FiniteSet(0, 1))
+
+    second_square = Interval(1, 2, True, True) * Interval(0, 1, True, True)
+    assert (open_square + second_square).boundary == (
+                FiniteSet(0, 1) * Interval(0, 1)
+              + FiniteSet(1, 2) * Interval(0, 1)
+              + Interval(0, 1) * FiniteSet(0, 1)
+              + Interval(1, 2) * FiniteSet(0, 1))
+
+
+def test_boundary_ProductSet_line():
+    line_in_r2 = Interval(0, 1) * FiniteSet(0)
+    assert line_in_r2.boundary == line_in_r2
+
+
+def test_is_open():
+    assert Interval(0, 1, False, False).is_open is False
+    assert Interval(0, 1, True, False).is_open is False
+    assert Interval(0, 1, True, True).is_open is True
+    assert FiniteSet(1, 2, 3).is_open is False
+
+
+def test_is_closed():
+    assert Interval(0, 1, False, False).is_closed is True
+    assert Interval(0, 1, True, False).is_closed is False
+    assert FiniteSet(1, 2, 3).is_closed is True
+
+
+def test_closure():
+    assert Interval(0, 1, False, True).closure == Interval(0, 1, False, False)
+
+
+def test_interior():
+    assert Interval(0, 1, False, True).interior == Interval(0, 1, True, True)
+
+
+def test_issue_7841():
+    raises(TypeError, lambda: x in S.Reals)
+
+
+def test_Eq():
+    assert Eq(Interval(0, 1), Interval(0, 1))
+    assert Eq(Interval(0, 1), Interval(0, 2)) == False
+
+    s1 = FiniteSet(0, 1)
+    s2 = FiniteSet(1, 2)
+
+    assert Eq(s1, s1)
+    assert Eq(s1, s2) == False
+
+    assert Eq(s1*s2, s1*s2)
+    assert Eq(s1*s2, s2*s1) == False
+
+    assert unchanged(Eq, FiniteSet({x, y}), FiniteSet({x}))
+    assert Eq(FiniteSet({x, y}).subs(y, x), FiniteSet({x})) is S.true
+    assert Eq(FiniteSet({x, y}), FiniteSet({x})).subs(y, x) is S.true
+    assert Eq(FiniteSet({x, y}).subs(y, x+1), FiniteSet({x})) is S.false
+    assert Eq(FiniteSet({x, y}), FiniteSet({x})).subs(y, x+1) is S.false
+
+    assert Eq(ProductSet({1}, {2}), Interval(1, 2)) is S.false
+    assert Eq(ProductSet({1}), ProductSet({1}, {2})) is S.false
+
+    assert Eq(FiniteSet(()), FiniteSet(1)) is S.false
+    assert Eq(ProductSet(), FiniteSet(1)) is S.false
+
+    i1 = Interval(0, 1)
+    i2 = Interval(x, y)
+    assert unchanged(Eq, ProductSet(i1, i1), ProductSet(i2, i2))
+
+
+def test_SymmetricDifference():
+    A = FiniteSet(0, 1, 2, 3, 4, 5)
+    B = FiniteSet(2, 4, 6, 8, 10)
+    C = Interval(8, 10)
+
+    assert SymmetricDifference(A, B, evaluate=False).is_iterable is True
+    assert SymmetricDifference(A, C, evaluate=False).is_iterable is None
+    assert FiniteSet(*SymmetricDifference(A, B, evaluate=False)) == \
+        FiniteSet(0, 1, 3, 5, 6, 8, 10)
+    raises(TypeError,
+        lambda: FiniteSet(*SymmetricDifference(A, C, evaluate=False)))
+
+    assert SymmetricDifference(FiniteSet(0, 1, 2, 3, 4, 5), \
+            FiniteSet(2, 4, 6, 8, 10)) == FiniteSet(0, 1, 3, 5, 6, 8, 10)
+    assert SymmetricDifference(FiniteSet(2, 3, 4), FiniteSet(2, 3, 4 ,5)) \
+            == FiniteSet(5)
+    assert FiniteSet(1, 2, 3, 4, 5) ^ FiniteSet(1, 2, 5, 6) == \
+            FiniteSet(3, 4, 6)
+    assert Set(S(1), S(2), S(3)) ^ Set(S(2), S(3), S(4)) == Union(Set(S(1), S(2), S(3)) - Set(S(2), S(3), S(4)), \
+            Set(S(2), S(3), S(4)) - Set(S(1), S(2), S(3)))
+    assert Interval(0, 4) ^ Interval(2, 5) == Union(Interval(0, 4) - \
+            Interval(2, 5), Interval(2, 5) - Interval(0, 4))
+
+
+def test_issue_9536():
+    from sympy.functions.elementary.exponential import log
+    a = Symbol('a', real=True)
+    assert FiniteSet(log(a)).intersect(S.Reals) == Intersection(S.Reals, FiniteSet(log(a)))
+
+
+def test_issue_9637():
+    n = Symbol('n')
+    a = FiniteSet(n)
+    b = FiniteSet(2, n)
+    assert Complement(S.Reals, a) == Complement(S.Reals, a, evaluate=False)
+    assert Complement(Interval(1, 3), a) == Complement(Interval(1, 3), a, evaluate=False)
+    assert Complement(Interval(1, 3), b) == \
+        Complement(Union(Interval(1, 2, False, True), Interval(2, 3, True, False)), a)
+    assert Complement(a, S.Reals) == Complement(a, S.Reals, evaluate=False)
+    assert Complement(a, Interval(1, 3)) == Complement(a, Interval(1, 3), evaluate=False)
+
+
+def test_issue_9808():
+    # See https://github.com/sympy/sympy/issues/16342
+    assert Complement(FiniteSet(y), FiniteSet(1)) == Complement(FiniteSet(y), FiniteSet(1), evaluate=False)
+    assert Complement(FiniteSet(1, 2, x), FiniteSet(x, y, 2, 3)) == \
+        Complement(FiniteSet(1), FiniteSet(y), evaluate=False)
+
+
+def test_issue_9956():
+    assert Union(Interval(-oo, oo), FiniteSet(1)) == Interval(-oo, oo)
+    assert Interval(-oo, oo).contains(1) is S.true
+
+
+def test_issue_Symbol_inter():
+    i = Interval(0, oo)
+    r = S.Reals
+    mat = Matrix([0, 0, 0])
+    assert Intersection(r, i, FiniteSet(m), FiniteSet(m, n)) == \
+        Intersection(i, FiniteSet(m))
+    assert Intersection(FiniteSet(1, m, n), FiniteSet(m, n, 2), i) == \
+        Intersection(i, FiniteSet(m, n))
+    assert Intersection(FiniteSet(m, n, x), FiniteSet(m, z), r) == \
+        Intersection(Intersection({m, z}, {m, n, x}), r)
+    assert Intersection(FiniteSet(m, n, 3), FiniteSet(m, n, x), r) == \
+        Intersection(FiniteSet(3, m, n), FiniteSet(m, n, x), r, evaluate=False)
+    assert Intersection(FiniteSet(m, n, 3), FiniteSet(m, n, 2, 3), r) == \
+        Intersection(FiniteSet(3, m, n), r)
+    assert Intersection(r, FiniteSet(mat, 2, n), FiniteSet(0, mat, n)) == \
+        Intersection(r, FiniteSet(n))
+    assert Intersection(FiniteSet(sin(x), cos(x)), FiniteSet(sin(x), cos(x), 1), r) == \
+        Intersection(r, FiniteSet(sin(x), cos(x)))
+    assert Intersection(FiniteSet(x**2, 1, sin(x)), FiniteSet(x**2, 2, sin(x)), r) == \
+        Intersection(r, FiniteSet(x**2, sin(x)))
+
+
+def test_issue_11827():
+    assert S.Naturals0**4
+
+
+def test_issue_10113():
+    f = x**2/(x**2 - 4)
+    assert imageset(x, f, S.Reals) == Union(Interval(-oo, 0), Interval(1, oo, True, True))
+    assert imageset(x, f, Interval(-2, 2)) == Interval(-oo, 0)
+    assert imageset(x, f, Interval(-2, 3)) == Union(Interval(-oo, 0), Interval(Rational(9, 5), oo))
+
+
+def test_issue_10248():
+    raises(
+        TypeError, lambda: list(Intersection(S.Reals, FiniteSet(x)))
+    )
+    A = Symbol('A', real=True)
+    assert list(Intersection(S.Reals, FiniteSet(A))) == [A]
+
+
+def test_issue_9447():
+    a = Interval(0, 1) + Interval(2, 3)
+    assert Complement(S.UniversalSet, a) == Complement(
+            S.UniversalSet, Union(Interval(0, 1), Interval(2, 3)), evaluate=False)
+    assert Complement(S.Naturals, a) == Complement(
+            S.Naturals, Union(Interval(0, 1), Interval(2, 3)), evaluate=False)
+
+
+def test_issue_10337():
+    assert (FiniteSet(2) == 3) is False
+    assert (FiniteSet(2) != 3) is True
+    raises(TypeError, lambda: FiniteSet(2) < 3)
+    raises(TypeError, lambda: FiniteSet(2) <= 3)
+    raises(TypeError, lambda: FiniteSet(2) > 3)
+    raises(TypeError, lambda: FiniteSet(2) >= 3)
+
+
+def test_issue_10326():
+    bad = [
+        EmptySet,
+        FiniteSet(1),
+        Interval(1, 2),
+        S.ComplexInfinity,
+        S.ImaginaryUnit,
+        S.Infinity,
+        S.NaN,
+        S.NegativeInfinity,
+        ]
+    interval = Interval(0, 5)
+    for i in bad:
+        assert i not in interval
+
+    x = Symbol('x', real=True)
+    nr = Symbol('nr', extended_real=False)
+    assert x + 1 in Interval(x, x + 4)
+    assert nr not in Interval(x, x + 4)
+    assert Interval(1, 2) in FiniteSet(Interval(0, 5), Interval(1, 2))
+    assert Interval(-oo, oo).contains(oo) is S.false
+    assert Interval(-oo, oo).contains(-oo) is S.false
+
+
+def test_issue_2799():
+    U = S.UniversalSet
+    a = Symbol('a', real=True)
+    inf_interval = Interval(a, oo)
+    R = S.Reals
+
+    assert U + inf_interval == inf_interval + U
+    assert U + R == R + U
+    assert R + inf_interval == inf_interval + R
+
+
+def test_issue_9706():
+    assert Interval(-oo, 0).closure == Interval(-oo, 0, True, False)
+    assert Interval(0, oo).closure == Interval(0, oo, False, True)
+    assert Interval(-oo, oo).closure == Interval(-oo, oo)
+
+
+def test_issue_8257():
+    reals_plus_infinity = Union(Interval(-oo, oo), FiniteSet(oo))
+    reals_plus_negativeinfinity = Union(Interval(-oo, oo), FiniteSet(-oo))
+    assert Interval(-oo, oo) + FiniteSet(oo) == reals_plus_infinity
+    assert FiniteSet(oo) + Interval(-oo, oo) == reals_plus_infinity
+    assert Interval(-oo, oo) + FiniteSet(-oo) == reals_plus_negativeinfinity
+    assert FiniteSet(-oo) + Interval(-oo, oo) == reals_plus_negativeinfinity
+
+
+def test_issue_10931():
+    assert S.Integers - S.Integers == EmptySet
+    assert S.Integers - S.Reals == EmptySet
+
+
+def test_issue_11174():
+    soln = Intersection(Interval(-oo, oo), FiniteSet(-x), evaluate=False)
+    assert Intersection(FiniteSet(-x), S.Reals) == soln
+
+    soln = Intersection(S.Reals, FiniteSet(x), evaluate=False)
+    assert Intersection(FiniteSet(x), S.Reals) == soln
+
+
+def test_issue_18505():
+    assert ImageSet(Lambda(n, sqrt(pi*n/2 - 1 + pi/2)), S.Integers).contains(0) == \
+            Contains(0, ImageSet(Lambda(n, sqrt(pi*n/2 - 1 + pi/2)), S.Integers))
+
+
+def test_finite_set_intersection():
+    # The following should not produce recursion errors
+    # Note: some of these are not completely correct. See
+    # https://github.com/sympy/sympy/issues/16342.
+    assert Intersection(FiniteSet(-oo, x), FiniteSet(x)) == FiniteSet(x)
+    assert Intersection._handle_finite_sets([FiniteSet(-oo, x), FiniteSet(0, x)]) == FiniteSet(x)
+
+    assert Intersection._handle_finite_sets([FiniteSet(-oo, x), FiniteSet(x)]) == FiniteSet(x)
+    assert Intersection._handle_finite_sets([FiniteSet(2, 3, x, y), FiniteSet(1, 2, x)]) == \
+        Intersection._handle_finite_sets([FiniteSet(1, 2, x), FiniteSet(2, 3, x, y)]) == \
+        Intersection(FiniteSet(1, 2, x), FiniteSet(2, 3, x, y)) == \
+        Intersection(FiniteSet(1, 2, x), FiniteSet(2, x, y))
+
+    assert FiniteSet(1+x-y) & FiniteSet(1) == \
+        FiniteSet(1) & FiniteSet(1+x-y) == \
+        Intersection(FiniteSet(1+x-y), FiniteSet(1), evaluate=False)
+
+    assert FiniteSet(1) & FiniteSet(x) == FiniteSet(x) & FiniteSet(1) == \
+        Intersection(FiniteSet(1), FiniteSet(x), evaluate=False)
+
+    assert FiniteSet({x}) & FiniteSet({x, y}) == \
+        Intersection(FiniteSet({x}), FiniteSet({x, y}), evaluate=False)
+
+
+def test_union_intersection_constructor():
+    # The actual exception does not matter here, so long as these fail
+    sets = [FiniteSet(1), FiniteSet(2)]
+    raises(Exception, lambda: Union(sets))
+    raises(Exception, lambda: Intersection(sets))
+    raises(Exception, lambda: Union(tuple(sets)))
+    raises(Exception, lambda: Intersection(tuple(sets)))
+    raises(Exception, lambda: Union(i for i in sets))
+    raises(Exception, lambda: Intersection(i for i in sets))
+
+    # Python sets are treated the same as FiniteSet
+    # The union of a single set (of sets) is the set (of sets) itself
+    assert Union(set(sets)) == FiniteSet(*sets)
+    assert Intersection(set(sets)) == FiniteSet(*sets)
+
+    assert Union({1}, {2}) == FiniteSet(1, 2)
+    assert Intersection({1, 2}, {2, 3}) == FiniteSet(2)
+
+
+def test_Union_contains():
+    assert zoo not in Union(
+        Interval.open(-oo, 0), Interval.open(0, oo))
+
+
+@XFAIL
+def test_issue_16878b():
+    # in intersection_sets for (ImageSet, Set) there is no code
+    # that handles the base_set of S.Reals like there is
+    # for Integers
+    assert imageset(x, (x, x), S.Reals).is_subset(S.Reals**2) is True
+
+def test_DisjointUnion():
+    assert DisjointUnion(FiniteSet(1, 2, 3), FiniteSet(1, 2, 3), FiniteSet(1, 2, 3)).rewrite(Union) == (FiniteSet(1, 2, 3) * FiniteSet(0, 1, 2))
+    assert DisjointUnion(Interval(1, 3), Interval(2, 4)).rewrite(Union) == Union(Interval(1, 3) * FiniteSet(0), Interval(2, 4) * FiniteSet(1))
+    assert DisjointUnion(Interval(0, 5), Interval(0, 5)).rewrite(Union) == Union(Interval(0, 5) * FiniteSet(0), Interval(0, 5) * FiniteSet(1))
+    assert DisjointUnion(Interval(-1, 2), S.EmptySet, S.EmptySet).rewrite(Union) == Interval(-1, 2) * FiniteSet(0)
+    assert DisjointUnion(Interval(-1, 2)).rewrite(Union) == Interval(-1, 2) * FiniteSet(0)
+    assert DisjointUnion(S.EmptySet, Interval(-1, 2), S.EmptySet).rewrite(Union) == Interval(-1, 2) * FiniteSet(1)
+    assert DisjointUnion(Interval(-oo, oo)).rewrite(Union) == Interval(-oo, oo) * FiniteSet(0)
+    assert DisjointUnion(S.EmptySet).rewrite(Union) == S.EmptySet
+    assert DisjointUnion().rewrite(Union) == S.EmptySet
+    raises(TypeError, lambda: DisjointUnion(Symbol('n')))
+
+    x = Symbol("x")
+    y = Symbol("y")
+    z = Symbol("z")
+    assert DisjointUnion(FiniteSet(x), FiniteSet(y, z)).rewrite(Union) == (FiniteSet(x) * FiniteSet(0)) + (FiniteSet(y, z) * FiniteSet(1))
+
+def test_DisjointUnion_is_empty():
+    assert DisjointUnion(S.EmptySet).is_empty is True
+    assert DisjointUnion(S.EmptySet, S.EmptySet).is_empty is True
+    assert DisjointUnion(S.EmptySet, FiniteSet(1, 2, 3)).is_empty is False
+
+def test_DisjointUnion_is_iterable():
+    assert DisjointUnion(S.Integers, S.Naturals, S.Rationals).is_iterable is True
+    assert DisjointUnion(S.EmptySet, S.Reals).is_iterable is False
+    assert DisjointUnion(FiniteSet(1, 2, 3), S.EmptySet, FiniteSet(x, y)).is_iterable is True
+    assert DisjointUnion(S.EmptySet, S.EmptySet).is_iterable is False
+
+def test_DisjointUnion_contains():
+    assert (0, 0) in DisjointUnion(FiniteSet(0, 1, 2), FiniteSet(0, 1, 2), FiniteSet(0, 1, 2))
+    assert (0, 1) in DisjointUnion(FiniteSet(0, 1, 2), FiniteSet(0, 1, 2), FiniteSet(0, 1, 2))
+    assert (0, 2) in DisjointUnion(FiniteSet(0, 1, 2), FiniteSet(0, 1, 2), FiniteSet(0, 1, 2))
+    assert (1, 0) in DisjointUnion(FiniteSet(0, 1, 2), FiniteSet(0, 1, 2), FiniteSet(0, 1, 2))
+    assert (1, 1) in DisjointUnion(FiniteSet(0, 1, 2), FiniteSet(0, 1, 2), FiniteSet(0, 1, 2))
+    assert (1, 2) in DisjointUnion(FiniteSet(0, 1, 2), FiniteSet(0, 1, 2), FiniteSet(0, 1, 2))
+    assert (2, 0) in DisjointUnion(FiniteSet(0, 1, 2), FiniteSet(0, 1, 2), FiniteSet(0, 1, 2))
+    assert (2, 1) in DisjointUnion(FiniteSet(0, 1, 2), FiniteSet(0, 1, 2), FiniteSet(0, 1, 2))
+    assert (2, 2) in DisjointUnion(FiniteSet(0, 1, 2), FiniteSet(0, 1, 2), FiniteSet(0, 1, 2))
+    assert (0, 1, 2) not in DisjointUnion(FiniteSet(0, 1, 2), FiniteSet(0, 1, 2), FiniteSet(0, 1, 2))
+    assert (0, 0.5) not in DisjointUnion(FiniteSet(0.5))
+    assert (0, 5) not in DisjointUnion(FiniteSet(0, 1, 2), FiniteSet(0, 1, 2), FiniteSet(0, 1, 2))
+    assert (x, 0) in DisjointUnion(FiniteSet(x, y, z), S.EmptySet, FiniteSet(y))
+    assert (y, 0) in DisjointUnion(FiniteSet(x, y, z), S.EmptySet, FiniteSet(y))
+    assert (z, 0) in DisjointUnion(FiniteSet(x, y, z), S.EmptySet, FiniteSet(y))
+    assert (y, 2) in DisjointUnion(FiniteSet(x, y, z), S.EmptySet, FiniteSet(y))
+    assert (0.5, 0) in DisjointUnion(Interval(0, 1), Interval(0, 2))
+    assert (0.5, 1) in DisjointUnion(Interval(0, 1), Interval(0, 2))
+    assert (1.5, 0) not in DisjointUnion(Interval(0, 1), Interval(0, 2))
+    assert (1.5, 1) in DisjointUnion(Interval(0, 1), Interval(0, 2))
+
+def test_DisjointUnion_iter():
+    D = DisjointUnion(FiniteSet(3, 5, 7, 9), FiniteSet(x, y, z))
+    it = iter(D)
+    L1 = [(x, 1), (y, 1), (z, 1)]
+    L2 = [(3, 0), (5, 0), (7, 0), (9, 0)]
+    nxt = next(it)
+    assert nxt in L2
+    L2.remove(nxt)
+    nxt = next(it)
+    assert nxt in L1
+    L1.remove(nxt)
+    nxt = next(it)
+    assert nxt in L2
+    L2.remove(nxt)
+    nxt = next(it)
+    assert nxt in L1
+    L1.remove(nxt)
+    nxt = next(it)
+    assert nxt in L2
+    L2.remove(nxt)
+    nxt = next(it)
+    assert nxt in L1
+    L1.remove(nxt)
+    nxt = next(it)
+    assert nxt in L2
+    L2.remove(nxt)
+    raises(StopIteration, lambda: next(it))
+
+    raises(ValueError, lambda: iter(DisjointUnion(Interval(0, 1), S.EmptySet)))
+
+def test_DisjointUnion_len():
+    assert len(DisjointUnion(FiniteSet(3, 5, 7, 9), FiniteSet(x, y, z))) == 7
+    assert len(DisjointUnion(S.EmptySet, S.EmptySet, FiniteSet(x, y, z), S.EmptySet)) == 3
+    raises(ValueError, lambda: len(DisjointUnion(Interval(0, 1), S.EmptySet)))
+
+def test_SetKind_ProductSet():
+    p = ProductSet(FiniteSet(Matrix([1, 2])), FiniteSet(Matrix([1, 2])))
+    mk = MatrixKind(NumberKind)
+    k = SetKind(TupleKind(mk, mk))
+    assert p.kind is k
+    assert ProductSet(Interval(1, 2), FiniteSet(Matrix([1, 2]))).kind is SetKind(TupleKind(NumberKind, mk))
+
+def test_SetKind_Interval():
+    assert Interval(1, 2).kind is SetKind(NumberKind)
+
+def test_SetKind_EmptySet_UniversalSet():
+    assert S.UniversalSet.kind is SetKind(UndefinedKind)
+    assert EmptySet.kind is SetKind()
+
+def test_SetKind_FiniteSet():
+    assert FiniteSet(1, Matrix([1, 2])).kind is SetKind(UndefinedKind)
+    assert FiniteSet(1, 2).kind is SetKind(NumberKind)
+
+def test_SetKind_Unions():
+    assert Union(FiniteSet(Matrix([1, 2])), Interval(1, 2)).kind is SetKind(UndefinedKind)
+    assert Union(Interval(1, 2), Interval(1, 7)).kind is SetKind(NumberKind)
+
+def test_SetKind_DisjointUnion():
+    A = FiniteSet(1, 2, 3)
+    B = Interval(0, 5)
+    assert DisjointUnion(A, B).kind is SetKind(NumberKind)
+
+def test_SetKind_evaluate_False():
+    U = lambda *args: Union(*args, evaluate=False)
+    assert U({1}, EmptySet).kind is SetKind(NumberKind)
+    assert U(Interval(1, 2), EmptySet).kind is SetKind(NumberKind)
+    assert U({1}, S.UniversalSet).kind is SetKind(UndefinedKind)
+    assert U(Interval(1, 2), Interval(4, 5),
+            FiniteSet(1)).kind is SetKind(NumberKind)
+    I = lambda *args: Intersection(*args, evaluate=False)
+    assert I({1}, S.UniversalSet).kind is SetKind(NumberKind)
+    assert I({1}, EmptySet).kind is SetKind()
+    C = lambda *args: Complement(*args, evaluate=False)
+    assert C(S.UniversalSet, {1, 2, 4, 5}).kind is SetKind(UndefinedKind)
+    assert C({1, 2, 3, 4, 5}, EmptySet).kind is SetKind(NumberKind)
+    assert C(EmptySet, {1, 2, 3, 4, 5}).kind is SetKind()
+
+def test_SetKind_ImageSet_Special():
+    f = ImageSet(Lambda(n, n ** 2), Interval(1, 4))
+    assert (f - FiniteSet(3)).kind is SetKind(NumberKind)
+    assert (f + Interval(16, 17)).kind is SetKind(NumberKind)
+    assert (f + FiniteSet(17)).kind is SetKind(NumberKind)
+
+def test_issue_20089():
+    B = FiniteSet(FiniteSet(1, 2), FiniteSet(1))
+    assert 1 not in B
+    assert 1.0 not in B
+    assert not Eq(1, FiniteSet(1, 2))
+    assert FiniteSet(1) in B
+    A = FiniteSet(1, 2)
+    assert A in B
+    assert B.issubset(B)
+    assert not A.issubset(B)
+    assert 1 in A
+    C = FiniteSet(FiniteSet(1, 2), FiniteSet(1), 1, 2)
+    assert A.issubset(C)
+    assert B.issubset(C)
+
+def test_issue_19378():
+    a = FiniteSet(1, 2)
+    b = ProductSet(a, a)
+    c = FiniteSet((1, 1), (1, 2), (2, 1), (2, 2))
+    assert b.is_subset(c) is True
+    d = FiniteSet(1)
+    assert b.is_subset(d) is False
+    assert Eq(c, b).simplify() is S.true
+    assert Eq(a, c).simplify() is S.false
+    assert Eq({1}, {x}).simplify() == Eq({1}, {x})
+
+def test_intersection_symbolic():
+    n = Symbol('n')
+    # These should not throw an error
+    assert isinstance(Intersection(Range(n), Range(100)), Intersection)
+    assert isinstance(Intersection(Range(n), Interval(1, 100)), Intersection)
+    assert isinstance(Intersection(Range(100), Interval(1, n)), Intersection)
+
+
+@XFAIL
+def test_intersection_symbolic_failing():
+    n = Symbol('n', integer=True, positive=True)
+    assert Intersection(Range(10, n), Range(4, 500, 5)) == Intersection(
+        Range(14, n), Range(14, 500, 5))
+    assert Intersection(Interval(10, n), Range(4, 500, 5)) == Intersection(
+        Interval(14, n), Range(14, 500, 5))
+
+
+def test_issue_20379():
+    #https://github.com/sympy/sympy/issues/20379
+    x = pi - 3.14159265358979
+    assert FiniteSet(x).evalf(2) == FiniteSet(Float('3.23108914886517e-15', 2))
+
+def test_finiteset_simplify():
+    S = FiniteSet(1, cos(1)**2 + sin(1)**2)
+    assert S.simplify() == {1}