#17720: failing primary decomposition with extension field coefficients
----------------------------+----------------------------
Reporter: jakobkroeker | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.5
Component: interfaces | Keywords: Singular
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: todo |
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The following bugs are likely Singular interface bugs (have to
investigate):
since the same examples run using shipped Singular behave differently
It may also relate to Singular's variable shadowing issue, see next ticket
0. working example:
{{{
sage: R.<b>=QQ[]
sage: K.<b>=QQ.extension(b^2-b-1)
sage: r.<x,z>=K[]
sage: I=r.ideal(z)
sage: L = I.primary_decomposition("gtz")
sage: [ J.gens() for J in L]
#[[z]]
}}}
1. example with wrong result:
{{{
sage: R.<p>=QQ[]
sage: K.<p>=QQ.extension(p^2-p-1)
sage: r.<x,z>=K[]
sage: I=r.ideal(z)
sage: L = I.primary_decomposition("gtz") # wrong!
sage: [ J.gens() for J in L]
#[[0, 0]]
}}}
2. crashing example:
{{{
sage: R.<p>=QQ[]
sage: K.<p>=QQ.extension(p^2-p-1)
sage: r.<x,z>=K[]
sage:
sage: I=r.ideal(z)
sage: I.primary_decomposition()
#RuntimeError: Error in Singular function call 'primdecSY':
# identifier pr not found in RH
# error occurred in or before primdec.lib::algeDeco line 2732: ` list
pr=imap(RH,pr);`
# leaving primdec.lib::algeDeco
# leaving primdec.lib::primdecSY
}}}
corresponding Singular code:
{{{
LIB("primdec.lib");
ring rng = (0,p),(x,z), dp;
minpoly = p^2-p-1;
ideal I = z;
primdecGTZ(I);
LIB("primdec.lib");
ring rng = (0,b),(x,z), dp;
minpoly = b^2-b-1;
ideal I = z;
primdecGTZ(I);
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/17720>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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