proposition: Lemma nth_lt_inspos i : i < pos -> (nth l Row i <= l)%O.
proof: Proof. Proof using. elim: Row i => [// | t0 r IHr] /=; case: (ltP l t0) => //= Ht. by case=> [// | i] /=; exact: IHr. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(perm fingroup) tools partition Yamanouchi ordtype subseq tableau std stdtab