proposition: Lemma Derivative_n_imp_Diffble_n : forall n F F', Derivative_n n I pI F F' -> Diffble_n n I pI F.
proof: Proof. intros n F F' H. elim H; intros incF H1. elim H1; intros incF' derivF. split; auto. intros; apply deriv_n_imp_Diffble_I_n with F'; auto. Qed.
imports: CoRN.ftc.MoreIntervals