unfold Rdiv.
intros.
rewrite <- (Rinv_r m)...
apply Rmult_lt_compat_r...
apply Rinv_0_lt_compat...
fourier.
intro.
subst.
apply (Rlt_not_le _ _ H0 H).
Qed.

(* Specifications: *)
Lemma zero_le_2_div_Sn n: 0 <= (2 * / INR (S n))%R.
Proof with auto with real.