[GAP Forum] question

[Ellis, Grahamj]

Dear Rashid,

I was just uploading a new version of HAP 1.7.3 when your e-mail arrived. So 
I have included a quickly written function NonabelianTensorProduct(G,N) which 
inputs a finite group G and normal subgroup N. It returns a record with the 
homomorphism delta:G\otimes N --> G and the crossed pairing h:G\times N --> G . 
I'll improve the efficiency of this function in the next release.

To calculate the order of the tensor product G\otimes N where G is the Sylow 
2-subgroup of the Mathieu group M12, and N the derived subgroup of G, you need to
type the following:

gap> G:=SylowSubgroup(MathieuGroup(12),2);;
gap> N:=DerivedSubgroup(G);;
gap> T:=NonabelianTensorProduct(G,N);;
gap> TensProd:=Source(T.homomorphism);
gap> Order(TensProd);
128

All the best,
Graham 













-----Original Message-----
From: forum-bounces at gap-system.org on behalf of rashid rezaei
Sent: Sun 11/03/2007 14:41
To: Forum at gap-system.org
Subject: [GAP Forum] question
 
Dear Forum,
   
  I am looking for computing the non-abelian tensor product $G\otimes N$ where $N$ is a normal subgroup of $G$. I found the command for tensor square in the package HAP, but I could not find any similar for $G\otimes N$. I will be more grateful for any help or comments.
  Regards,
   
  R. Rezaei.

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