(** * Additional results not mentioned in the paper *)
From Undecidability.L Require Import Encodings.
(** ** Natural numbers *)
(** *** Predecessor and multiplication *)
Definition Pred : term := .\"n"; "n" !Zero (.\"n"; "n").
Hint Unfold Pred : cbv.

Lemma Mul_correct m n :
Mul (enc n) (enc m) ≡ enc (n * m).