proposition: Lemma mcoeff_symm sh m : size sh <= n -> 'm[sh]@_m = (perm_eq (mpart (n := n) sh) m)%:R.
proof: Proof. by move=> H; rewrite /symm H mcoeff_symm_pol. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(ssralg ssrint fingroup perm) mathcomp(ssrcomplements freeg mpoly) sorted tools ordtype permuted partition skewpart composition Yamanouchi std tableau stdtab skewtab permcent antisym Schur_mpoly therule Schur_altdef unitriginv