proposition: Lemma mesym_sym k : 's_k \is symmetric.
proof: Proof. apply/issymP=> s; apply/mpolyP=> m. by rewrite mcoeff_sym !mcoeff_mesym mperm_mechar. 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