Section Derive'.
Context {V : CompleteNormedModule R_AbsRing}.

(* Specifications: *)
Lemma is_RInt_derive (f df : R -> V) (a b : R) :
(forall x : R, Rmin a b <= x <= Rmax a b -> is_derive f x (df x)) ->
(forall x : R, Rmin a b <= x <= Rmax a b -> continuous df x) ->
is_RInt df a b (minus (f b) (f a)).