proposition: Fact lb_meet_length a b : length a = length b -> length (a↓b) = length a.
proof: Proof. revert b; induction a as [ | x a IHa ]; intros [ | y b ]; try discriminate; auto; intros H. rewrite lb_meet_cons; simpl; f_equal; auto. Qed.
imports: List Lia Bool Setoid Undecidability.Shared.Libs.DLW.Utils(utils_tac)