def create_key_and_extra_args(self, X, Y, category=None, base=ZZ,
check=True, as_point_homset=False):
"""
Create a key that uniquely determines the Hom-set.
INPUT:
- ``X`` -- a scheme. The domain of the morphisms.
- ``Y`` -- a scheme. The codomain of the morphisms.
- ``category`` -- a category for the Hom-sets (default: schemes over
given base).
- ``base`` -- a scheme or a ring. The base scheme of domain
and codomain schemes. If a ring is specified, the spectrum
of that ring will be used as base scheme.
- ``check`` -- boolean (default: ``True``).
EXAMPLES::
sage: A2 = AffineSpace(QQ,2)
sage: A3 = AffineSpace(QQ,3)
sage: A3.Hom(A2) # indirect doctest
Set of morphisms
From: Affine Space of dimension 3 over Rational Field
To: Affine Space of dimension 2 over Rational Field
sage: from sage.schemes.generic.homset import SchemeHomsetFactory
sage: SHOMfactory = SchemeHomsetFactory('test')
sage: key, extra = SHOMfactory.create_key_and_extra_args(A3,A2,check=False)
sage: key
(..., ..., Category of schemes over Integer Ring, False)
sage: extra
{'X': Affine Space of dimension 3 over Rational Field,
'Y': Affine Space of dimension 2 over Rational Field,
'base_ring': Integer Ring,
'check': False}
"""
if isinstance(X, CommutativeRing):
X = AffineScheme(X)
if isinstance(Y, CommutativeRing):
Y = AffineScheme(Y)
if is_AffineScheme(base):
base_spec = base
base_ring = base.coordinate_ring()
elif isinstance(base, CommutativeRing):
base_spec = AffineScheme(base)
base_ring = base
else:
raise ValueError('base must be a commutative ring or its spectrum')
if not category:
from sage.categories.schemes import Schemes
category = Schemes(base_spec)
key = tuple([id(X), id(Y), category, as_point_homset])
extra = {'X':X, 'Y':Y, 'base_ring':base_ring, 'check':check}
return key, extra
def __init__(self, n, R, names):
"""
EXAMPLES::
sage: AffineSpace(3, Zp(5), 'y')
Affine Space of dimension 3 over 5-adic Ring with capped relative precision 20
"""
AmbientSpace.__init__(self, n, R)
self._assign_names(names)
AffineScheme.__init__(self, self.coordinate_ring(), R)
def __init__(self, n, R, names):
"""
EXAMPLES::
sage: AffineSpace(3, Zp(5), 'y')
Affine Space of dimension 3 over 5-adic Ring with capped relative precision 20
"""
AmbientSpace.__init__(self, n, R)
self._assign_names(names)
AffineScheme.__init__(self, self.coordinate_ring(), R)
def __init__(self, base_ring=None):
"""
EXAMPLES::
sage: from sage.schemes.generic.spec import SpecFunctor
sage: SpecFunctor()
Spec functor from Category of commutative rings to Category of schemes
sage: SpecFunctor(QQ)
Spec functor from Category of commutative rings to
Category of schemes over Rational Field
"""
from sage.categories.all import CommutativeAlgebras, CommutativeRings, Schemes
if base_ring is None:
domain = CommutativeRings()
codomain = Schemes()
elif base_ring in CommutativeRings():
# We would like to use CommutativeAlgebras(base_ring) as
# the domain; we use CommutativeRings() instead because
# currently many algebras are not yet considered to be in
# CommutativeAlgebras(base_ring) by the category framework.
domain = CommutativeRings()
codomain = Schemes(AffineScheme(base_ring))
else:
raise TypeError('base (= {}) must be a commutative ring'.format(base_ring))
self._base_ring = base_ring
super(SpecFunctor, self).__init__(domain, codomain)
def __init__(self, n, R, names, ambient_projective_space, default_embedding_index):
"""
EXAMPLES::
sage: AffineSpace(3, Zp(5), 'y')
Affine Space of dimension 3 over 5-adic Ring with capped relative precision 20
"""
AmbientSpace.__init__(self, n, R)
self._assign_names(names)
AffineScheme.__init__(self, self.coordinate_ring(), R)
index = default_embedding_index
if index is not None:
index = int(index)
self._default_embedding_index = index
self._ambient_projective_space = ambient_projective_space
def _apply_functor(self, A):
"""
Apply the Spec functor to the commutative ring ``A``.
EXAMPLES::
sage: from sage.schemes.generic.spec import SpecFunctor
sage: F = SpecFunctor()
sage: F(RR) # indirect doctest
Spectrum of Real Field with 53 bits of precision
"""
# The second argument of AffineScheme defaults to None.
# However, AffineScheme has unique representation, so there is
# a difference between calling it with or without explicitly
# giving this argument.
if self._base_ring is None:
return AffineScheme(A)
return AffineScheme(A, self._base_ring)
def _apply_functor(self, A):
"""
Apply the Spec functor to the commutative ring ``A``.
EXAMPLES::
sage: from sage.schemes.generic.spec import SpecFunctor
sage: F = SpecFunctor()
sage: F(RR) # indirect doctest
Spectrum of Real Field with 53 bits of precision
"""
return AffineScheme(A, self._base_ring)
def __init__(self, R, S=None):
"""
Construct the spectrum of the ring ``R``.
See :class:`Spec` for details.
EXAMPLES::
sage: Spec(ZZ)
Spectrum of Integer Ring
"""
if not is_CommutativeRing(R):
raise TypeError, "R (=%s) must be a commutative ring"%R
self.__R = R
if not S is None:
if not is_CommutativeRing(S):
raise TypeError, "S (=%s) must be a commutative ring"%S
try:
S.hom(R)
except TypeError:
raise ValueError, "There must be a natural map S --> R, but S = %s and R = %s"%(S,R)
AffineScheme.__init__(self, S)
def __init__(self, R, S=None):
"""
Construct the spectrum of the ring ``R``.
See :class:`Spec` for details.
EXAMPLES::
sage: Spec(ZZ)
Spectrum of Integer Ring
"""
if not is_CommutativeRing(R):
raise TypeError("R (=%s) must be a commutative ring"%R)
self.__R = R
if not S is None:
if not is_CommutativeRing(S):
raise TypeError("S (=%s) must be a commutative ring"%S)
try:
S.hom(R)
except TypeError:
raise ValueError("There must be a natural map S --> R, but S = %s and R = %s"%(S,R))
AffineScheme.__init__(self, S)
