proposition: Lemma mdeg_mesym1 h : mdeg (mesym1 h) = #|h|.
proof: Proof. rewrite mdegE (bigID (mem h)) /= addnC big1 ?add0n; last first. by move=> i i_notin_h; rewrite mnmE (negbTE i_notin_h). rewrite (eq_bigr (fun _ => 1%N)) ?sum1_card //. by move=> i i_in_h; rewrite mnmE i_in_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