proposition: Fact Forall2_mono X Y (R S : X -> Y -> Prop) : (forall x y, R x y -> S x y) -> forall l m, Forall2 R l m -> Forall2 S l m.
proof: Proof. induction 2; constructor; auto. Qed.
imports: List Arith Lia Permutation Undecidability.Shared.Libs.DLW.Utils(list_focus utils_tac)