proposition: Lemma mult_nf alpha beta : nf alpha -> nf beta -> nf (alpha * beta).
proof: Proof. intros Halpha Hbeta; rewrite <- nf_ref in *; rewrite mult_ref; now apply T1.mult_nf. Qed.
imports: hydras(T1 E0 Comparable) Coq(Arith Logic.Eqdep_dec Peano_dec List Bool Recdef Lia Wellfounded.Inverse_Image Wellfounded.Inclusion RelationClasses )