#20146: Bug in computing the Gröner fan
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Reporter: stumpc5 | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-7.1
Component: commutative algebra | Resolution:
Keywords: Gröbner basis, Gröbner fan, | Merged in:
gfan | Reviewers:
Authors: | Work issues:
Report Upstream: N/A | Commit:
Branch: | Stopgaps:
Dependencies: |
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Comment (by stumpc5):
The problem is that the gfan code uses {{{ideal_to_gfan_format}}} which
expects the generators of an ideal to come as a list. But they don't:
{{{
sage: P =
PolynomialRing(QQ,"x11,x12,x13,x14,x21,x22,x23,x24,x31,x32,x33,x34"); x =
P.gens(); M = Matrix(3,x)
sage: I = P.ideal(M.minors(2))
sage: I.gens()
[-x12*x21 + x11*x22, -x13*x21 + x11*x23, -x14*x21 + x11*x24, -x13*x22 +
x12*x23, -x14*x22 + x12*x24, -x14*x23 + x13*x24, -x12*x31 + x11*x32,
-x13*x31 + x11*x33, -x14*x31 + x11*x34, -x13*x32 + x12*x33, -x14*x32 +
x12*x34, -x14*x33 + x13*x34, -x22*x31 + x21*x32, -x23*x31 + x21*x33,
-x24*x31 + x21*x34, -x23*x32 + x22*x33, -x24*x32 + x22*x34, -x24*x33 +
x23*x34]
sage: P =
PolynomialRing(QQ,"x11,x12,x13,x14,x15,x21,x22,x23,x24,x25,x31,x32,x33,x34,x35");
x = P.gens(); M = Matrix(3,x)
sage: I = P.ideal(M.minors(2))
sage: I.gens()
Polynomial Sequence with 30 Polynomials in 15 Variables
}}}
I will provide a patch preparsing {{{I.gens()}}} before giving it to
{{{ideal_to_gfan_format}}}.
--
Ticket URL: <http://trac.sagemath.org/ticket/20146#comment:5>
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