proposition: Lemma is_skew_tableau0 : is_skew_tableau [::] =1 is_tableau.
proof: Proof. Proof using. elim => //= t0 t IHt; rewrite add0n subn0 skew_dominate0 IHt. by case t0. Qed.
imports: HB(structures) mathcomp(all_ssreflect) tools partition skewpart Yamanouchi ordtype tableau std stdtab