On 2013-02-15, at 10:35 , Sven Reichard <sven.reich...@tu-dresden.de> wrote:
> -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Am 15.02.2013 10:02, schrieb rahul kitture: >> Given two subgroups $H$ and $K$ of a finite group (say Symmetric/ >> Alternating Group), how do we compute the product $HK$ in the >> group? I couldn't find anything from Help or topics in online >> library. > > This may not be the most elegant way, but > gap> Group(Concatenation(List([H,K], GeneratorsOfGroup)), Identity(H)); > should do the trick. This gives the subgroup generated by H and K but not, in general, the set HK. If you know that HK is a subgroup, then this will work. ClosureGroup (H,K) might be a bit more efficient. On 2013-02-15, at 14:27 , Sandeep Murthy <sandeepr.mur...@gmail.com> wrote: > Hi, > > If H, K are subgroups of G then > > ListX( H, K, PROD ) > > will return a (mutable) list of > the elements > of the set HK in > G. But note that the list will have duplicates if H and K don't intersect trivially. I would suggest DoubleCoset (H, One(H), K) to represent HK more efficiently. You can turn the double coset into a list via AsList/ AsSSortedList. Cheers Burkhard. _______________________________________________ Forum mailing list Forum@mail.gap-system.org http://mail.gap-system.org/mailman/listinfo/forum
