proposition: Lemma rcent_group_set : group_set rcent.
proof: Proof. apply/group_setP; rewrite inE group1 repr_mx1 mulmx1 mul1mx; split=> //= x y. case/setIdP=> Gx; move/eqP=> cfx; case/setIdP=> Gy; move/eqP=> cfy. by rewrite inE repr_mxM ?groupM //= -mulmxA -cfy !mulmxA cfx. 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)