unfold ratInverse.
case_eq rat1; intuition.
inversion H; clear H; subst.
eapply eqRat_terms;
trivial.
Qed.

(* Specifications: *)
Lemma ratInverse_leRat : forall r1 r2,
~ r2 == 0 ->
r2 <= r1 ->
ratInverse r1 <= ratInverse r2.