proposition: Lemma derivable_derive : forall f x (pr:derivable_pt f x), exists l, derive_pt f x pr = l.
proof: Proof. intros f x pr ; exists (proj1_sig pr) ; reflexivity. 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