proposition: Lemma symmX d (la : 'P_d) : 'hm[la](X) = 'hm[la].
proof: Proof. by have /(congr1 val) := map_symm (mpolyC n (R:=R)) m0 la. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(ssrint rat ssralg ssrnum algC matrix vector) mathcomp(mpoly) tools partition ordtype antisym Schur_mpoly Schur_altdef sympoly homogsym permcent