Opaque Pred_e.
(** Def 3 of (Rose) *)
Definition OneMinus'_e : Cobham :=
Rec2
(One_e 0)
(Zero_e 2)
(One_e 1).

Lemma OneMinus'_correct : forall l,
hd nil l = nil \/ bs2nat (hd nil l) <> 0 ->
bs2nat (Sem OneMinus'_e l) = 1 - bs2nat (hd nil l).