proposition: Lemma mperm_mechar k (m : 'X_{1..n}) (s : 'S_n) : mechar k (m#s) = mechar k m.
proof: Proof. rewrite /mechar mdeg_mperm; congr (_ && _). apply/forallP/forallP=> //=. + by move=> h i; move/(_ (s^-1 i))%g: h; rewrite mnmE permKV. + by move=> h i; rewrite mnmE; apply/h. 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