proposition: Lemma cnvar_symm (la : 'P_d) : cnvarsym 'm[la] = 'm[la].
proof: Proof. rewrite !symm_syms linear_sum; apply eq_bigr => mu _. by rewrite linearZ /= cnvar_syms. 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