proposition: Lemma nonempty_dom `{laws} `{TOP ≪ l} n m {x: X n m} {Hx: is_nonempty x}: is_nonempty' n.
proof: Proof. intros i j. rewrite nonempty. mrewrite (leq_xt (x⋅top' _ j)). ra. Qed.
imports: common lattice monoid kleene normalisation rewriting