proposition: Lemma le_3_4 : 3 ≤ 4.
proof: Proof. apply (order_preserving (1+)), le_2_3. Qed.
imports: Coq.setoid_ring.Ring MathClasses.interfaces.abstract_algebra MathClasses.interfaces.orders MathClasses.theory.rings MathClasses.orders.orders MathClasses.orders.maps