#12211: bug in equation checking for quasi projective/affine schemes
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Reporter: davideklund | Owner: AlexGhitza
Type: defect | Status: new
Priority: minor | Milestone: sage-4.8
Component: algebraic geometry | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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The method {{{_check_satisfies_equations}}} of the class
{{{AlgebraicScheme_quasi}}} checks whether a point p lies on the
complement of a scheme Y in a scheme X.
If one of the equations defining Y vanishes, then p is judged not a point
on X-Y, but it could be that some other equation defining Y does not
vanish.
Example:
{{{
sage: P.<x, y, z, w> = ProjectiveSpace(3, QQ)
sage: S = P.subscheme([x])
sage: T = P.subscheme([y, z])
sage: U = T.complement(S)
sage: U._check_satisfies_equations([0,0,1,1])
...
TypeError: Coordinates [0, 0, 1, 1] do not define a point on Quasi-
projective subscheme X - Y of Projective Space of dimension 3 over
Rational Field, where X is defined by:
x
and Y is defined by:
y,
z
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12211>
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