proposition: Lemma row_mx_cup `{L: lattice.laws} n m1 m2 M M' N N': @row_mx X n m1 m2 (M ⊔ M') (N ⊔ N') ≡ row_mx M N ⊔ row_mx M' N'.
proof: Proof. intros i j. unfold row_mx. simpl. case split; reflexivity. Qed.
imports: comparisons kleene sums normalisation