[GAP Forum] complex product of two groups

[Alexander Hulpke]

Dear William,

If you use 
DoubleCoset(H,One(H),K)
creation is very cheap and membership tests reasonable (they use a decomposition as union of right cosets). You also could get elements if you really wanted.
However if you do other set operations (union, intersection etc.) iGAP likely will unpack to a list.

Best,

   Alexander Hulpke

-- Colorado State University, Department of Mathematics,
Weber Building, 1874 Campus Delivery, Fort Collins, CO 80523-1874, USA
email: hulpke at math.colostate.edu, Phone: ++1-970-4914288
http://www.math.colostate.edu/~hulpke