proposition: Lemma mdeg_mperm m (s : 'S_n) : mdeg (m#s) = mdeg m.
proof: Proof. rewrite !mdegE (reindex_inj (h := s^-1))%g /=; last exact/perm_inj. by apply/eq_bigr=> j _; rewrite !mnmE permKV. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(choice fintype tuple finfun bigop finset binomial) mathcomp(order fingroup perm ssralg zmodp poly ssrint) mathcomp(matrix vector) mathcomp(bigenough) ssrcomplements freeg