Opened 4 years ago

Last modified 7 months ago

#18598 new defect

reduce method of polynomial ideals gives incorrect results

Reported by: lftabera Owned by:
Priority: major Milestone: sage-8.4
Component: algebra Keywords: days94
Cc: Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Description

The following fails 

sage: K=PolynomialRing(QQ,'x,y,a0,a1',order=TermOrder('degrevlex',2)+TermOrder('degrevlex',2))
sage: x,y,a0,a1=K.gens()
sage: f = x**3+x**2*y
sage: m = Ideal(x**4,x**2*y,y**2)
sage: m.reduce(f) == f.reduce(m.groebner_basis())
False
sage: m.reduce(f)
x^3 + x^2*y
sage: f.reduce(m.groebner_basis())
x^3

The reduction should be x^3. Singular computes correctly the reduction, so the problem is in the Sage library.

Change History (3)

comment:1 Changed 8 months ago by lftabera

  • Keywords days94 added
  • Milestone changed from sage-6.8 to sage-8.3

comment:2 Changed 8 months ago by lftabera

I am not able to debug this. For me, it seems that this is an error in libsingular and, probably, a duplicate of #12529

comment:3 Changed 7 months ago by vdelecroix

  • Milestone changed from sage-8.3 to sage-8.4

update milestone 8.3 -> 8.4

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