[GAP Forum] Using M12 semidirect product Z_2 in GAP

[Dmitrii Pasechnik]

On Mon, Jan 04, 2016 at 01:07:01PM +0530, Aniket Joshi wrote:
> I wish to find the homology H_3(M_{12} : Z_2, Z), where M_{12} is a Mathieu
> group of order 95040, and M_12:Z_2 indicates the semi-direct product with
> Z_2. I plan to use the GroupHomology(,)  command from the HAP package for
> GAP.
> 
> How do I use the semi direct product M_12:Z_2 in GAP? Is there an inbuilt
> function, or would I need to compute it separately?
just take 

assuming you have AltasRep package installed, you can just do

 AtlasGroup("M12:2")

to get a permutation representation of M:12:2 on 24 points.

HTH,
Dmitrii