Opened 10 years ago

Closed 22 months ago

#12803 closed defect (fixed)

quotient of ideals throws up Singular bug

Reported by: mariah Owned by: malb
Priority: minor Milestone: sage-9.1
Component: commutative algebra Keywords:
Cc: malb Merged in:
Authors: Markus Wageringel Reviewers: Kwankyu Lee
Report Upstream: Fixed upstream, in a later stable release. Work issues:
Branch: 873857a (Commits, GitHub, GitLab) Commit: 873857a0005b3a2cb0979bf4b04918dab9bf8d30
Dependencies: Stopgaps: #17679

Status badges

Description (last modified by jdemeyer)

This is a bug in Singular 3.1.7 (fixed in 4.0.1, see ticket #17254): 

R.<xe,xv> = ZZ[]

J = Ideal(4*xv^3+3*xv^2, 3*xe*xv^2+xe-2*xv);

I  = Ideal(-3, -3*xv-1, -3);
I2 = Ideal(-3, -3*xv-1);
assert( I  == I2 )

Q1 = J.quotient(I) # wrong
Q2 = J.quotient(I2)

assert( Q1 == Q2 ) # fails

Change History (14)

comment:1 Changed 10 years ago by SimonKing

  • Cc malb added
  • Component changed from algebra to commutative algebra
  • Owner changed from AlexGhitza to malb

comment:2 Changed 8 years ago by jdemeyer

  • Milestone changed from sage-5.11 to sage-5.12

comment:3 Changed 8 years ago by vbraun_spam

  • Milestone changed from sage-6.1 to sage-6.2

comment:4 Changed 8 years ago by jakobkroeker

This bug (and some others) are fixed in recent ​Singular: 

ring rng = integer,(x,y,z),dp;
ideal A = x^2, x*y, x*z;
ideal B = x;
quotient(A,B);
//_[1]=z
//_[2]=y
//_[3]=x

(offtopic: are all known Singular-bugs reported ​upstream? )

However, I recall that there are some issues when considering updating Singular :

  • there is no stable/official release yet
  • in sage-devel (?, cannot currently find the post I had in mind) it was mentioned that the libSingular interface changed significantly in comparison to v 3.1.6

comment:5 Changed 8 years ago by vbraun_spam

  • Milestone changed from sage-6.2 to sage-6.3

comment:6 Changed 7 years ago by vbraun_spam

  • Milestone changed from sage-6.3 to sage-6.4

comment:7 Changed 7 years ago by jakobkroeker

  • Report Upstream changed from N/A to Fixed upstream, in a later stable release.

comment:8 Changed 7 years ago by jakobkroeker

the bug above is fixed by upgrade to Singular 3.1.7

but there is at least another one (fixed in 4.0.1, see ticket #17254): 

R.<xe,xv> = ZZ[]

J = Ideal(4*xv^3+3*xv^2, 3*xe*xv^2+xe-2*xv);

I  = Ideal(-3, -3*xv-1, -3);
I2 = Ideal(-3, -3*xv-1);
assert( I  == I2 )

Q1 = J.quotient(I) # wrong
Q2 = J.quotient(I2)


assert( Q1 == Q2 ) # fails

comment:9 Changed 7 years ago by jakobkroeker

  • Description modified (diff)

comment:10 Changed 7 years ago by jakobkroeker

  • Stopgaps set to #17679

comment:11 Changed 7 years ago by jdemeyer

  • Description modified (diff)

comment:12 Changed 2 years ago by gh-mwageringel

  • Authors set to Markus Wageringel
  • Branch set to u/gh-mwageringel/12803
  • Commit set to 873857a0005b3a2cb0979bf4b04918dab9bf8d30
  • Milestone changed from sage-6.4 to sage-9.1
  • Priority changed from major to minor
  • Status changed from new to needs_review

Since the bug is fixed, here is a branch removing the stopgap warning and adding the example from the description as a doctest.

(Ignore the pyflakes warning for now. I will deal with it on another ticket, as the unused macaulay2 variable should actually be used.)

New commits:

​873857a12803: remove stopgap and add doctest

comment:13 Changed 23 months ago by klee

  • Reviewers set to Kwankyu Lee
  • Status changed from needs_review to positive_review

LGTM

comment:14 Changed 22 months ago by vbraun

  • Branch changed from u/gh-mwageringel/12803 to 873857a0005b3a2cb0979bf4b04918dab9bf8d30
  • Resolution set to fixed
  • Status changed from positive_review to closed
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