proposition: Lemma derivable_opp : forall f, derivable f -> derivable (- f).
proof: Proof. intros f1 Hf1 z ; apply derivable_pt_opp ; intuition. Qed.
imports: MyRIneq Rinterval Ranalysis_def Ranalysis_def_simpl Ranalysis_continuity Ranalysis_derivability Ranalysis_usual Ranalysis_facts Ranalysis_MVT Canalysis_diff Cprop_base Cnorm Ctacfield Cmet Canalysis_def Cderiv