proposition: Lemma mlead_mesym k (le_kn : k <= n) : mlead 's_k = [multinom (i < k : nat) | i < n].
proof: Proof. rewrite -mesymlmE /mlead (bigD1_seq (mesymlm k)) //=; last first. rewrite mem_msupp_mesym mecharP; apply/existsP. by exists (mesymlmnm k); rewrite card_mesymlmnm ?eqxx. apply/join_l/joinsP_seq=> /= {}m. rewrite msupp_mesymP => /existsP[/=]. move=> h /andP[/eqP Chk /eqP->] _; rewrite -Chk. by apply/mesymlm_max; rewrite Chk. 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