intros x y H'; unfold FtoR in |- *; simpl in |- *.
repeat rewrite Rmult_1_l; auto with real zarith.
apply Rle_powerRZ; try replace 1%R with (IZR 1); auto with real zarith zarith.
Qed.

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