[GAP Forum] groups of order 512 inconsistency

[Max Horn]

Dear Benjamin,

> On 2. Apr 2020, at 11:54, Benjamin Sambale <benjamin.sambale at gmail.com> wrote:
> 
> Dear GAP people,
> 
> I noticed the following unexpected behavior in GAP 4.11.0 (and some older versions):
> 
> G:=SmallGroup(2^9,261648);;
> H:=Image(IsomorphismPermGroup(G));
> Size(Center(G)); #returns 4
> Size(Center(H)); #returns 8
> 
> The same happens if we convert into an fp group. Other groups of order 512 and 1536 are affected as well.
> I know very little about pc groups, but my guess is that the presentation of G is somewhat inconsistent, although the problem does not occur in MAGMA.

Thank you very much for the report. That's of course a rather concerning issue.

We have logged it at <https://github.com/gap-system/gap/issues/3940> and will look into this as soon as possible.

Best regards
Max