#12211: bug in equation checking for quasi projective/affine schemes
----------------------------------+-----------------------------------------
Reporter: davideklund | Owner: AlexGhitza
Type: defect | Status: needs_review
Priority: minor | Milestone: sage-4.8
Component: algebraic geometry | Keywords:
Work_issues: | Upstream: N/A
Reviewer: Volker Braun | Author: David Eklund
Merged: | Dependencies:
----------------------------------+-----------------------------------------
Changes (by davideklund):
* status: new => needs_review
Old description:
> 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
> }}}
New description:
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
}}}
Apply [attachment:trac_12211_fix_bug.2.patch]
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12211#comment:3>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
