Ambient spaces¶
-
class
sage.schemes.generic.ambient_space.
AmbientSpace
(n, R=Integer Ring)¶ Bases:
sage.schemes.generic.scheme.Scheme
Base class for ambient spaces over a ring.
INPUT:
n
- dimensionR
- ring
-
ambient_space
()¶ Return the ambient space of the scheme self, in this case self itself.
EXAMPLES:
sage: P = ProjectiveSpace(4, ZZ) sage: P.ambient_space() is P True sage: A = AffineSpace(2, GF(3)) sage: A.ambient_space() Affine Space of dimension 2 over Finite Field of size 3
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base_extend
(R)¶ Return the natural extension of
self
overR
.INPUT:
R
– a commutative ring, such that there is a natural map from the base ring of self toR
.
OUTPUT:
an ambient space over
R
of the same structure asself
.
Note
A
ValueError
is raised if there is no such natural map. If you need to drop this condition, useself.change_ring(R)
.EXAMPLES:
sage: P.<x, y, z> = ProjectiveSpace(2, ZZ) sage: PQ = P.base_extend(QQ); PQ Projective Space of dimension 2 over Rational Field sage: PQ.base_extend(GF(5)) Traceback (most recent call last): ... ValueError: no natural map from the base ring (=Rational Field) to R (=Finite Field of size 5)!
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change_ring
(R)¶ Return an ambient space over ring \(R\) and otherwise the same as self.
INPUT:
R
– commutative ring
OUTPUT:
ambient space over
R
Note
There is no need to have any relation between \(R\) and the base ring of self, if you want to have such a relation, use
self.base_extend(R)
instead.
-
defining_polynomials
()¶ Return the defining polynomials of the scheme self. Since self is an ambient space, this is an empty list.
EXAMPLES:
sage: ProjectiveSpace(2, QQ).defining_polynomials() () sage: AffineSpace(0, ZZ).defining_polynomials() ()
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dimension
()¶ Return the absolute dimension of this scheme.
EXAMPLES:
sage: A2Q = AffineSpace(2, QQ) sage: A2Q.dimension_absolute() 2 sage: A2Q.dimension() 2 sage: A2Z = AffineSpace(2, ZZ) sage: A2Z.dimension_absolute() 3 sage: A2Z.dimension() 3
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dimension_absolute
()¶ Return the absolute dimension of this scheme.
EXAMPLES:
sage: A2Q = AffineSpace(2, QQ) sage: A2Q.dimension_absolute() 2 sage: A2Q.dimension() 2 sage: A2Z = AffineSpace(2, ZZ) sage: A2Z.dimension_absolute() 3 sage: A2Z.dimension() 3
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dimension_relative
()¶ Return the relative dimension of this scheme over its base.
EXAMPLES:
sage: A2Q = AffineSpace(2, QQ) sage: A2Q.dimension_relative() 2 sage: A2Z = AffineSpace(2, ZZ) sage: A2Z.dimension_relative() 2
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gen
(n=0)¶ Return the \(n\)-th generator of the coordinate ring of the scheme self.
EXAMPLES:
sage: P.<x, y, z> = ProjectiveSpace(2, ZZ) sage: P.gen(1) y
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gens
()¶ Return the generators of the coordinate ring of the scheme self.
EXAMPLES:
sage: AffineSpace(0, QQ).gens() () sage: P.<x, y, z> = ProjectiveSpace(2, GF(5)) sage: P.gens() (x, y, z)
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is_projective
()¶ Return whether this ambient space is projective n-space.
EXAMPLES:
sage: AffineSpace(3,QQ).is_projective() False sage: ProjectiveSpace(3,QQ).is_projective() True
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ngens
()¶ Return the number of generators of the coordinate ring of the scheme self.
EXAMPLES:
sage: AffineSpace(0, QQ).ngens() 0 sage: ProjectiveSpace(50, ZZ).ngens() 51
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sage.schemes.generic.ambient_space.
is_AmbientSpace
(x)¶ Return True if \(x\) is an ambient space.
EXAMPLES:
sage: from sage.schemes.generic.ambient_space import is_AmbientSpace sage: is_AmbientSpace(ProjectiveSpace(3, ZZ)) True sage: is_AmbientSpace(AffineSpace(2, QQ)) True sage: P.<x, y, z> = ProjectiveSpace(2, ZZ) sage: is_AmbientSpace(P.subscheme([x+y+z])) False