Hi,
(after having a Singular bug in the computation of its Hilbert series, i
now have a bug in computing the Gröbner fan:
First one annoyance (yes, x1 is a prefix of x11) that I want to point out:
{{{
sage: P = PolynomialRing(QQ,3*5,"x"); x = P.gens(); M = Matrix(3,x)
sage: M
[ x0 x1 x2 x3 x4]
[ x5 x6 x7 x8 x9]
[x10 x11 x12 x13 x14]
sage: I = P.ideal(M.minors(2))
sage: I.groebner_fan()
---------------------------------------------------------------------------
RuntimeError Traceback (most recent call last)
...
RuntimeError: Ring variables cannot contain each other as prefixes
}}}
and then the bug:
{{{
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: M
[x11 x12 x13 x14 x15]
[x21 x22 x23 x24 x25]
[x31 x32 x33 x34 x35]
sage: I = P.ideal(M.minors(2))
sage: gf = I.groebner_fan()
sage: rgbs = gf.reduced_groebner_bases()
---------------------------------------------------------------------------
RuntimeError Traceback (most recent call last)
...
RuntimeError: Unknown
variable:olynomialSequencewith30Polynomialsin15Variable
gfan_bases: parser.cpp:276: virtual Monomial
CharacterBasedParser::parseMonomial(const PolynomialRing&): Assertion `0'
failed.
}}}
It does still work for four columns in the matrix instead...
Thanks for having a look, Christian
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