[GAP Forum] Testing action of automorphisms on groups

[Siddhartha Sarkar]

Thanks Stephen,

I just found it.

gap> A:=AutomorphismGroupPGroup(g);;

gap> IsGroup(A);

false


Applying it directly with AutomorphismGroup works.

Thanks,
Siddhartha

On Sun, Feb 23, 2020 at 5:21 PM Stephen Linton <sl4 at st-andrews.ac.uk> wrote:

> Ah I see. Your group B is made using PcGroupAutPcGroup. This essentially
> forgets that the group is an automorphism group and simply computes an
> isomorphic PC Group ( at least for the soluble part). If you want to work
> with the automorphisms as such, you either need to work directly in the
> AutomorphismGroup, or keep track of the explicit isomorphism between that
> group and a PC group.
>
>
>
>      Steve
>
>
>
>
>
>
>
> *From: *Siddhartha Sarkar <siddhartha18 at gmail.com>
> *Date: *Sunday, 23 February 2020 at 11:39
> *To: *Stephen Linton <sl4 at st-andrews.ac.uk>
> *Cc: *GAP Forum <forum at gap-system.org>
> *Subject: *Re: Testing action of automorphisms on groups
>
>
>
> Dear Stephen,
>
>
>
> Thanks. It still shows an error.
>
>
>
> Siddhartha
>
>
>
> gap> p:=Image(a1,x1);
>
> Error, usage: Image(<map>), Image(<map>,<elm>), Image(<map>,<coll>) at
> /Users/sidhu/Desktop/GAP/gap-4.10.2/lib/mapping.gi:198 called from
>
> <function "Image">( <arguments> )
>
>  called from read-eval loop at *stdin*:19
>
> you can 'quit;' to quit to outer loop, or
>
> you can 'return;' to continue
>
> brk> return;
>
> Error, Function call: <func> must return a value
>
> not in any function at *stdin*:19
>