Opaque MultTwoPowerLength_e.
(** Def 14 of (Rose) *)
Definition DivTwoPower'_e : Cobham :=
Rec2
(Proj 1 0)
(Comp 3 Div2_e [Proj 3 1])
(Proj 2 1).

Lemma DivTwoPower'_correct : forall l,
bs2nat (Sem DivTwoPower'_e l) =
fun_power (length (hd nil l)) div2 (bs2nat (hd nil (tl l))).