End Derive.

(* Specifications: *)
Lemma Derive_RInt (f : R -> R) (a b : R) :
locally b (ex_RInt f a) -> continuous f b
-> Derive (RInt f a) b = f b.
Lemma Derive_RInt' (f : R -> R) (a b : R) :
locally a (fun a => ex_RInt f a b) -> continuous f a
-> Derive (fun a => RInt f a b) a = - f a.