induction n1; intuition; simpl in *.
symmetry.
eapply expRat_1.
rewrite expRat_exp_sum.
rewrite IHn1.
rewrite expRat_base_prod.
intuition.
Qed.

Lemma expRat_le_exp_exists : forall r d,
~ 1 <= r ->
~ d == 0 ->
exists n,
expRat r n <= d.