proposition: Lemma meet_sl_le_spec x y : x ≤ y ↔ x ⊓ y = x.
proof: Proof. split; intros E. now apply meet_l. rewrite <-E. now apply meet_lb_r. Qed.
imports: MathClasses.interfaces.abstract_algebra MathClasses.interfaces.orders MathClasses.orders.maps MathClasses.theory.lattices