[GAP Forum] Zappa-Szep product, knit product

[Rudolf Zlabinger]

Dear Professor Neubüser,

thank you for your suggestion, I will follow now.

The Zappa Szep product is said to be a generalization of the semidirect product in that sense, that both of the factors embedded images (if there are such images) in the product are not normal subgroups of the product. The internal form of the Zappa Szep product is simply the complexes product of two non normal subgroups with trivial intersection. I am interested mainly on the external form of. 

I found a short description of the Zappa Szep product in the following link:

http://en.wikipedia.org/wiki/Zappa-Szep_product

In the link there are also references to related textbooks.

Thank you for your hint so far, kind regards, Rudolf Zlabinger




----- Original Message ----- 
From: "Joachim Neubueser" <joachim.neubueser at math.rwth-aachen.de>
To: "Rudolf Zlabinger" <Rudolf.Zlabinger at chello.at>
Sent: Thursday, December 28, 2006 1:50 PM
Subject: Re: [GAP Forum] Zappa-Szep product, knit product


> Dear Dr. Zlabinger
> 
> 
> On Wed, Dec 13, 2006 at 03:02:27PM +0100, you wrote to the GAP Forum:
> 
>> Is there any  code known in GAP (I scanned the  docs, but I couldn't
>> find anything about), or  any free code, implementing the Zappa-Szep
>> product (Knit product) for groups?
> 
>> 
>> thank you, Rudolf Zlabinger 
> 
> As far  as I see, there  has been no answer  in the Forum  so far. One
> reason  may be that  most of  the Forum  members (as  is the  case for
> myself) do  not know the  notion of a  Zappa-Szep product. While  I am
> rather sure  that nothing  of that  name is in  the GAP  library, some
> people may  have suggestions how  to write code for  its construction,
> once they  understand the definition.   May I suggest that  you repeat
> the  question but  with a  brief  description of  the definition  (and
> perhaps what it 'is good for').
> 
> Kind regards     Joachim Neubueser
> 
>