proposition: Lemma mx_str_blk' n m (M: mx (X u u) (n+m) (n+m)): M^* ≡ mx_str_build X u n m (mx_str _ _ _) (mx_str _ _ _) M.
proof: Proof. apply str_unique'. apply mx_str_build_unfold_l; apply mx_str_unfold_l. apply mx_str_build_ind_l; intros ? ? ?; apply mx_str_ind_l. Qed.
imports: kleene normalisation ordinal sups matrix