proposition: Lemma map_symm d : map_sympoly 'm[d] = 'm[d].
proof: Proof. apply val_inj; rewrite /= /symm. case: leqP => _ /=; last exact: rmorph0. rewrite /symm_pol rmorph_sum /=. apply eq_bigr => X _; exact: map_mpolyX. 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