(** ** Theorems proved using standard library *)

(* Specifications: *)
Lemma ex_RInt_norm :
forall (f : R -> R) a b, ex_RInt f a b ->
ex_RInt (fun x => norm (f x)) a b.
Lemma abs_RInt_le :
forall (f : R -> R) a b,
a <= b -> ex_RInt f a b ->
Rabs (RInt f a b) <= RInt (fun t => Rabs (f t)) a b.