proposition: Lemma Acc_wlt_Acc_wlt_zs : forall (n:nat) (w:(list nat)), (Acc wlt w) -> (Acc wlt (app (zs n) w)).
proof: Proof. intros. apply Acc_intro. intros w' H0. apply H. apply wlt_zs_wlt_right with (n:=n). assumption. Qed.
imports: Arith Coq.Logic.Eqdep_dec Coq.Arith.Peano_dec List Recdef