proposition: Lemma succ_nf alpha : nf alpha -> nf (succ alpha).
proof: Proof. intro H; rewrite <- nf_ref in *; rewrite succ_ref; now apply T1.succ_nf. Qed.
imports: hydras(T1 E0 Comparable) Coq(Arith Logic.Eqdep_dec Peano_dec List Bool Recdef Lia Wellfounded.Inverse_Image Wellfounded.Inclusion RelationClasses )