proposition: Lemma ratMult_num_den : forall n1 n2 d1 d2, (RatIntro (n1 * n2)%nat (posnatMult d1 d2)) == (RatIntro n1 d1) * (RatIntro n2 d2).
proof: Proof. intuition. unfold ratMult, natToPosnat, posnatMult. eapply eqRat_refl. Qed.
imports: micromega.Lia List FCF.StdNat Arith Lia Setoid RelationClasses Coq.Classes.Morphisms