proposition: Lemma behead_incr_nth (s : seq nat) nrow : behead (incr_nth s nrow.+1) = incr_nth (behead s) nrow.
proof: Proof. Proof using. by elim: s => //=; case nrow. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(perm fingroup) tools partition Yamanouchi ordtype subseq tableau std stdtab