Opened 10 years ago

Closed 10 years ago

#12211 closed defect (fixed)

bug in equation checking for quasi projective/affine schemes

Reported by: davideklund Owned by: AlexGhitza
Priority: minor Milestone: sage-4.8
Component: algebraic geometry Keywords:
Cc: Merged in: sage-4.8.alpha6
Authors: David Eklund Reviewers: Volker Braun
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Status badges

Description (last modified by davideklund)

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 trac_12211_fix_bug.2.patch

Attachments (2)

trac_12211_fix_bug.patch (1003 bytes) - added by davideklund 10 years ago.
Fixes the bug.
trac_12211_fix_bug.2.patch (1.4 KB) - added by davideklund 10 years ago.
Fix bug, contains doctest (patch made with Sage 4.7.2).

Download all attachments as: .zip

Change History (7)

Changed 10 years ago by davideklund

Fixes the bug.

comment:1 Changed 10 years ago by davideklund

  • Authors set to David Eklund

comment:2 Changed 10 years ago by vbraun

  • Reviewers set to Volker Braun

Can you add your example to the doctest?

comment:3 Changed 10 years ago by davideklund

  • Description modified (diff)
  • Status changed from new to needs_review

Changed 10 years ago by davideklund

Fix bug, contains doctest (patch made with Sage 4.7.2).

comment:4 Changed 10 years ago by vbraun

  • Status changed from needs_review to positive_review

Looks good!

comment:5 Changed 10 years ago by jdemeyer

  • Merged in set to sage-4.8.alpha6
  • Resolution set to fixed
  • Status changed from positive_review to closed
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