[GAP Forum] A question

[Joe Bohanon]

Make sure you've got a good representation of your group, too.  If it's
solvable, use

iso:=IsomorphismPcGroup(G);
H:=Image(iso);

then run on H (and use PreImage(iso,I) where I is the result of the code
below).

If not solvable, use IsomorphismPermGroup and maybe also
SmallerDegreePermutationRepresentation.

ConjugacyClassesSubgroups stalls very badly if you feed it a finitely
presented group.

Even WITH the PC presentation, some of the higher rank groups of order 256
will stall badly on the "ConjugacyClassesSubgroups" command.

Joe

On Sun, Nov 7, 2010 at 5:18 AM, Benjamin Sambale <bsambale at gmx.de> wrote:

> maybe the following is faster (and does not need the sonata package):
>
>
> I:=G; #G is a group
> for H in List(ConjugacyClassesSubgroups(G),Representative) do
>
>    I:=Intersection(I,Normalizer(G,DerivedSubgroup(H)));
> od;
> I:=Core(G,I);
>
> Am 07.11.2010 09:38, schrieb Benjamin Sambale:
>
>  try this:
>>
>> LoadPackage("sonata");
>> I:=G; #G is a group
>> for H in Subgroups(G) do
>>    I:=Intersection(I,Normalizer(G,DerivedSubgroup(H)));
>> od;
>> #now I is the intersection you want
>>
>> best wishes,
>> Benjamin
>>
>> Am 07.11.2010 08:13, schrieb 刘建军:
>>
>>> Dear forum,
>>>
>>> Let $G$ be a finite group. I would like to know that the intersection of
>>> the normalizers of derived subgroups of all subgroups of $G$.
>>> Is there a method to get it in GAP?
>>>
>>> Best Wishes
>>> Jianjun Liu
>>>
>>> _______________________________________________
>>> Forum mailing list
>>> Forum at mail.gap-system.org
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>>>
>>>
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