proposition: Lemma mem_mesym1_mesym h : mesym1 h \in msupp 's_#|h|.
proof: Proof. rewrite mem_msupp_mesym mecharP; apply/existsP. by exists h; rewrite !eqxx. 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