proposition: Lemma rembig_plact2i u v : u \in (plact2i v) -> rembig u = rembig v.
proof: Proof. Proof using. by rewrite -plact2I => /rembig_plact2 ->. Qed.
imports: mathcomp(all_ssreflect) mathcomp(perm) tools partition ordtype tableau stdtab Schensted congr