proposition: Lemma map_group_ring : (group_ring aR G)^f = group_ring rR G.
proof: Proof. rewrite map_enveloping_algebra_mx; apply/row_matrixP=> i. by rewrite !rowK map_regular_repr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div choice fintype tuple finfun bigop prime) mathcomp(ssralg poly polydiv finset fingroup morphism) mathcomp(perm automorphism quotient finalg action zmodp) mathcomp(commutator cyclic center pgroup matrix mxalgebra) mathcomp(mxpoly)