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Fix an error in evaluating the MaximalAbelianQuotient of a subgroup o…
…f an FPGroup which could result in wrong results (#5620) * Conjugacy test for cyclic subgroups Do not try the orbit mapping test for cyclic subgroups (or subgroups with many orbits). Thiscould be memory intensive, and is done reasonably by backtrack. This resolves #5564 * FIX: Abelianized subgroup rewriting Replace method for `MaximalAbelianQuotient` for a subgroup with an easier version that rewrites the presentation and then abelianizes. This fixes #5609 * ENHANCE: AGSRCharacteristicSeries refine Only attempt refinements with PCore, Agemo, Omega, if steps are not already elementary abelian. This can avoid expensive subcomputations.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,32 @@ | ||
| # Reported by don't know, # 5609 | ||
| gap> f := FreeGroup("a", "b", "c", "d", "e");; | ||
| gap> a := f.1;;b := f.2;;c := f.3;;d := f.4;;e := f.5;; | ||
| gap> g := f / [a^2, b^2, c^2, d^2, e^2, (a*b)^5, (a*c)^2, (a*d)^2, (a*e)^2, | ||
| > (b*c)^3, (b*d)^2, (b*e)^2, (c*d)^3, (c*e)^2, (d*e)^3];; | ||
| gap> w1 := ElementOfFpGroup(FamilyObj(g.1), a*b*c*d*e);; | ||
| gap> w2 := ElementOfFpGroup(FamilyObj(g.1), | ||
| > b*a*b*c*b*a*b*a*c*b*a*d*c*e*d*c*b*a*b*a*c*d*e*b*c*a*b*a*b*c*d*c*b*a | ||
| > *b*c*a*b*a*b*c);; | ||
| gap> w3 := ElementOfFpGroup(FamilyObj(g.1), | ||
| > b*a*b*c*b*a*d*c*b*a*b*a*c*b*a*d*e*d*c*b*a*b*c*d*e*a*b*a*b*c*d*b*a*b | ||
| > *c*a*b*a*b*c*d*c*b);; | ||
| gap> w4 := ElementOfFpGroup(FamilyObj(g.1), | ||
| > b*c*b*a*b*a*d*c*b*a*b*a*c*b*a*b*c*d*c*b*a*b*a*c*d*b*c*a*b*a*b*c*d*e | ||
| > *b*c*a*b*a*b*c*d*b*a*b*c*a*b);; | ||
| gap> w5 := ElementOfFpGroup(FamilyObj(g.1), | ||
| > b*a*b*a*c*d*c*b*a*b*a*c*b*a*d*c*b*a*b*c*d*e*d*c*b*a*b*c*d*a*b*c*a*b | ||
| > *a*b*c*d*e*b*a*b*c*d*b*c*a*b*a*b*c);; | ||
| gap> s := Subgroup(g, [w1, w2, w3, w4, w5]);; | ||
| gap> s1 := Subgroup(g, [w1, w2^-2, w3*w2^-1, w3^-1*w2^-1, w4*w2^-1, | ||
| > w4^-1*w2^-1, w5*w2^-1, w5^-1*w2^-1]);; | ||
| gap> s2:=Subgroup(g,[w1^-2, w2, w3, w4*w1^-1, w1*w2*w1^-1, w1*w3*w1^-1, w5]);; | ||
| gap> ab := MaximalAbelianQuotient(s);; | ||
| gap> q1 := GQuotients(s1, SymmetricGroup(2));; | ||
| gap> q2 := GQuotients(s2, SymmetricGroup(2));; | ||
| gap> k1 := Kernel(q1[7]);; | ||
| gap> nr:=First(Concatenation([7],[1..Length(q2)]),x->Kernel(q2[x])=k1);; | ||
| gap> k2 := Kernel(q2[nr]);; | ||
| gap> k1=k2; | ||
| true | ||
| gap> Image(ab,k1)=Image(ab,k2); | ||
| true |