gap> G:=Group((1,2),(1,2,3,4));; gap> K:=Rationals;; gap> KG:=GroupRing(K,G); gap> emb:=Embedding(G,KG);; gap> ((1,2)^emb+(1,2,3)^emb)^3; (1)*()+(1)*(2,3)+(2)*(1,2)+(2)*(1,2,3)+(1)*(1,3,2)+(1)*(1,3) gap> clsum2:=Sum(List(ConjugacyClass(G,(1,2)),x->x^emb)); (1)*(3,4)+(1)*(2,3)+(1)*(2,4)+(1)*(1,2)+(1)*(1,3)+(1)*(1,4) gap> basisG:=Basis(KG); CanonicalBasis( ) gap> li:=List(basisG,x->x*clsum2);; gap> U:=Subspace(KG,li);;Dimension(U); 20 gap> quit;