I am trying to look at a representation (so a homomorphism) of a group G, and see what the restriction of the representation to a subgroup of G will be. Is there an easy way (or any way!) to do this in MAGMA?
If your representation R is of type Map (which it will be if you defined it as Representation(M) for a Gmodule M), then to restrict R to subgroup H RH := map< H>Codomain(R)  x :> R(x) >; should work. If you have defined R as a group homomorphism G > GL(n,K) for some field K, then you could instead use RH := hom< H>Codomain(R)  x :> R(x) >; 

