proposition: Lemma cnvarsym_subproof (p : {sympoly R[m]}) : sympolyf p \mPo E \is symmetric.
proof: Proof. by apply mcomp_sym => i; rewrite -tnth_nth tnth_mktuple mesym_sym. 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