quotient of ideals throws up Singular bug

[sagetrac-mariah]

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

Upstream: Fixed upstream, in a later stable release.

CC: @malb

Component: commutative algebra

Stopgaps: #17679

Author: Markus Wageringel

Branch/Commit: 873857a

Reviewer: Kwankyu Lee

Issue created by migration from https://trac.sagemath.org/ticket/12803

[sagetrac-jakobkroeker]

comment:4

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