fact: Definition symm_pol (sh : n.-tuple nat) : {mpoly R[n]} := \sum_(p : permuted sh) 'X_[Multinom p].
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