proposition: Lemma plactrule_homog : forall u : word, all (perm_eq u) (plactrule u).
proof: Proof. Proof using. move=> u. by rewrite !all_cat plact1_homog plact1i_homog plact2_homog plact2i_homog. Qed.
imports: mathcomp(all_ssreflect) mathcomp(perm) tools partition ordtype tableau stdtab Schensted congr