id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,merged,author,reviewer,upstream,work_issues,branch,commit,dependencies,stopgaps
7736,"factor returns a reducible factor,",syazdani,cremona,"Here is a result that confuses me (appologies for not having a simpler example for this):
{{{
sage: E = EllipticCurve('1728z');
sage: Et = E.mod5family();
sage: f=Et.discriminant().numerator().factor()[0][0];
sage: K. = NumberField(f);
sage: f.change_ring(K).factor()[1][0].is_irreducible()
False
}}}
Here f turns out to be a degree 12 polynomial, and when you factor it over K, you get a linear factor and a degree 11 factor. However, degree 11 factor in this case is not irreducible. In fact, if you continue with
{{{
sage: g = f.change_ring(K).factor()[1][0];
sage: g.factor()
}}}
you get a linear factor and a degree 10 factor, where both are irreducible.
I fear it is no good asking for an upstream fix, since they (pari) have already fixed it but we are not using the fixed version. See #7097 for more details.",defect,closed,critical,sage-duplicate/invalid/wontfix,factorization,duplicate,number field pari,wuthrich was,,,,N/A,,,,,