[GAP Forum] complex product of two groups

[Arnaldo Mandel]

On Wed, Apr 18, 2012 at 10:11 AM, Sandeep Murthy
<sandeepr.murthy at gmail.com>wrote:

> Hi,
>
> This command
>
>    ListX( H, K, PROD )
>



Most likely,

Set(ListX( H, K, PROD  ))

will give what he wants.









>
> will do the product, seems fairly quick.
>
> SRM
>
>
> On 18 Apr 2012, at 13:49, William DeMeo wrote:
>
> > Dear Forum,
> >
> > If I have two subgroups H and K of a group G, what's the best way to
> > form what I think is sometimes called the "complex product"?  That is,
> > I want to form the set
> >
> > HK = { hk : h in H, k in K }
> >
> > (I don't want the group generated by H and K.)
> >
> > Below is a listing of the obvious/dumb algorithm, but I suspect
> > there's a better way to do this in GAP.  If someone knows of one,
> > please let me know.
> >
> > Thanks!
> > -William
> >
> >
> > HK:=[];
> > for h in H do
> >   for k in K do
> >      if h*k not in HK then
> >         Add(HK,h*k);
> >      fi;
> >   od;
> > od;
> >
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>
>
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