Section Recr.
(** [recr] satisfies the fixpoint equation used for its definition. *)
Variable (A:Type)(case0:A)(caserec:digits->int31->A->A).

Lemma recr_aux_converges :
forall n p x, n <= size -> n <= p ->
recr_aux n A case0 caserec (nshiftr x (size - n)) =
recr_aux p A case0 caserec (nshiftr x (size - n)).