proposition: Lemma issym_msupp p (s : 'S_n) (m : 'X_{1..n}) : p \is symmetric -> (m#s \in msupp p) = (m \in msupp p).
proof: Proof. by rewrite !mcoeff_msupp -mcoeff_sym => /issymP ->. 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