Opened 5 years ago

Closed 2 years ago

#24377 closed PLEASE CHANGE (invalid)

Wrong results when using singular functions

Reported by: Enrique Artal Bartolo Owned by:
Priority: major Milestone: sage-duplicate/invalid/wontfix
Component: algebraic geometry Keywords: singular
Cc: Merged in:
Authors: Reviewers:
Report Upstream: Reported upstream. No feedback yet. Work issues:
Branch: Commit:
Dependencies: Stopgaps:

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In sage (version 8.1, but 8.0 has the same issue) I have the following code: R.<x,y>=PolynomialRing??(QQ,order='neglex') f=(y2+x3)*(y2+x3+x2*y) singular.lib("all.lib") f._singular_().bernstein()

I guess this is equivalent to the following singular code LIB "all.lib"; ring r=0,(x,y),ds; poly f=(y2+x3)*(y2+x3+x2y) bernstein(f)

The results differ: -11/7 is a root in the first case, while -4/7 in the second (and I think there are theoretical results that ensure the second one is correct); moreover in both cases, when using bfct -4/7 is the root (bfct uses another algorithm to compute the Bernstein-Sato polynomial). The Singular computations are done using both an external Singular installation and the Sage one.

In other cases I had communication problems between singular and sage leading to output errors, but in this case it produces (a non evident) mathematical wrong result.

Change History (2)

comment:1 Changed 5 years ago by Enrique Artal Bartolo

After discussion with upstream, it is related to the dependence on orderings of the rings, so I guess it can be closed.

comment:2 Changed 2 years ago by Frédéric Chapoton

Milestone: sage-8.2sage-duplicate/invalid/wontfix
Resolution: invalid
Status: newclosed
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