proposition: Lemma mpermKV (s : 'S_n) : cancel (fun m => m#s) (fun m => m#(s^-1))%g.
proof: Proof. by move=> m /=; apply/mnmP=> i; 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