intros x y H'; case (Zle_or_lt y x); auto; intros ZH; Contradict H'.
apply Rle_not_lt; apply oneExp_le; auto.
Qed.

(* Specifications: *)
Theorem oneExp_Zle :
forall x y : Z, (Float 1%nat x <= Float 1%nat y)%R -> (x <= y)%Z.