Dear GAP-Forum,

Nicola Sottonorcola asked:

I have to do some (simple?) computations like this with GAP:

GG:=Group((1,2,4,6)(3,5,7,8), (1,3)(2,5));
H:=DirectProduct(DihedralGroup(4),DihedralGroup(4));
IsomorphicSubgroups( GG, H );

The groups are quite small:

|GG|=32, |H|=16

but GAP seems very slow in doing computations like this.

The runtime of `IsomorphicSubgroups' grows with the number of generators of
the groups inolved. Thus it does not work well for $p$-groups.
It was mainly intended for groups that can be generated by 2 elements, in
particular to find (almost) simple and perfect subgroups.

> Are there a more rapid way to obtain these results?
I would compute the subgroup lattice and use `IdGroup' to determine the type
of the representatives.

Best,

Alexander Hulpke

-- Colorado State University, Department of Mathematics,
Weber Building, Fort Collins, CO 80523, USA
email: hulpke@math.colostate.edu, Phone: ++1-970-4914288
http://www.math.colostate.edu/~hulpke

Miles-Receive-Header: reply