proposition: Lemma KP_arrowS_zero n beta : KP_arrowS n zero beta -> beta = zero.
proof: Proof. intros H; red in H; rewrite <- clos_trans_t1n_iff in H. rewrite clos_trans_tn1_iff in H. induction H. - destruct H as [x [H H0]]; inversion H0. now destruct H1. - subst; destruct H as [x [H1 H2]]. inversion H2. now destruct H1. Qed.
imports: hydras(DecPreOrder Canon MoreLists First_toggle OrdNotations) Coq(Lia)