intros e n; elim n; unfold Zpower_nat in |- *; simpl in |- *;
auto with zarith.
Qed.
Hint Resolve Zpower_NR0 Zpower_NR1: zarith.
(* To define exponential over relative number, we simply do a case analysis on the sign of the number *)
(*Definition powerRZ := [e : R] [n : Z]  Cases n of ZERO => R1 | (POS p) => (pow e (convert p)) | (NEG p) => (Rinv (pow e (convert p))) end.*)
(* we now prove some basic properties of our exponential *)

Theorem powerRZ_O : forall e : R, powerRZ e 0 = 1%R.
simpl in |- *; auto.