(* 
   Returns the list of relative numbers from z to z+n *)
 
Fixpoint mZlist_aux (p : Z) (n : nat) {struct n} : 
 list Z :=
  match n with
  | O => p :: nil
  | S n1 => p :: mZlist_aux (Zsucc p) n1
  end.

Theorem mZlist_aux_correct : forall (n : nat) (p q : Z), (p <= q)%Z -> (q <= p + Z_of_nat n)%Z -> In q (mZlist_aux p n).