proposition: Lemma Forall2_impl (A B : Type) (R1 R2 : A -> B -> Prop) : (forall a b, R1 a b -> R2 a b) -> forall l1 l2, Forall2 R1 l1 l2 -> Forall2 R2 l1 l2.
proof: Proof. intros HPQ l1 l2 HPl1l2. induction HPl1l2; now eauto using Forall2. Qed.
imports: PeanoNat