#12803: quotient of ideals throws up Singular bug
-------------------------------------------------+-------------------------
Reporter: mariah | Owner: malb
Type: defect | Status: new
Priority: major | Milestone: sage-6.4
Component: commutative algebra | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: Fixed upstream, in a later | Work issues:
stable release. | Commit:
Branch: | Stopgaps: #17679
Dependencies: |
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Description changed by jdemeyer:
Old description:
> {{{
> sage: var('x,y,z')
> (x, y, z)
> sage: R = ZZ[x,y,z]
> sage: A = R.ideal([x^2, x*y, x*z])
> sage: B = R.ideal([x])
> sage: A.quotient(B)
> ---------------------------------------------------------------------------
> RuntimeError Traceback (most recent call
> last)
>
> /home/mariah/sage/sage-4.8-x86_64-Linux-core2-fc/<ipython console> in
> <module>()
>
> /home/mariah/sage/sage-4.8-x86_64-Linux-core2-fc/local/lib/python2.6
> /site-packages/sage/rings/polynomial/multi_polynomial_ideal.pyc in
> wrapper(*args, **kwds)
> 500 """
> 501 with LibSingularDefaultContext():
> --> 502 return func(*args, **kwds)
> 503 return wrapper
> 504
>
> /home/mariah/sage/sage-4.8-x86_64-Linux-core2-fc/local/lib/python2.6
> /site-packages/sage/rings/polynomial/multi_polynomial_ideal.pyc in
> quotient(self, J)
> 2224 import sage.libs.singular
> 2225 quotient = sage.libs.singular.ff.quotient
> -> 2226 return R.ideal(quotient(self, J))
> 2227
> 2228 @require_field
>
> /home/mariah/sage/sage-4.8-x86_64-Linux-core2-fc/local/lib/python2.6
> /site-packages/sage/libs/singular/function.so in
> sage.libs.singular.function.SingularFunction.__call__
> (sage/libs/singular/function.cpp:10130)()
>
> /home/mariah/sage/sage-4.8-x86_64-Linux-core2-fc/local/lib/python2.6
> /site-packages/sage/libs/singular/function.so in
> sage.libs.singular.function.call_function
> (sage/libs/singular/function.cpp:11392)()
>
> /home/mariah/sage/sage-4.8-x86_64-Linux-core2-fc/local/lib/python2.6
> /site-packages/sage/libs/singular/function.so in
> sage.libs.singular.function.call_function
> (sage/libs/singular/function.cpp:11306)()
>
> RuntimeError: Segmentation fault
> sage:
> }}}
>
> 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
> }}}
New description:
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
}}}
--
--
Ticket URL: <http://trac.sagemath.org/ticket/12803#comment:11>
Sage <http://www.sagemath.org>
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