Definition Succ_e : Cobham :=
Comp 1 (Succ true) [Proj 1 0].
Opaque Succ_e.
Fixpoint Nat_e (n:nat) : Cobham :=
match n with
| 0 => Zero
| S n' => Comp 0 Succ_e [Nat_e n']
end.
Notation Plus_e := App_e.
Notation arity_Plus := arity_App.
Notation rec_bounded_Plus := rec_bounded_App.

Lemma Plus_correct : forall l,
length (Sem Plus_e l) = length (hd nil l) + length (hd nil (tl l)).