proposition: Lemma posnatMult_comm : forall p1 p2, (posnatEq (posnatMult p1 p2) (posnatMult p2 p1)).
proof: Proof. intuition. unfold posnatMult. destruct p1; destruct p2. econstructor. apply Nat.mul_comm. Qed.
imports: Arith micromega.Lia Coq.NArith.BinNat