proposition: Lemma Rint_le_compat : forall f g a b x y, a <= b -> (forall u, a < u < b -> f u <= g u) -> Rint f a b x -> Rint g a b y -> x <= y.
proof: Proof. intros f g a b x y Hab Heq [prh Hf] [prg Hg]. rewrite <- Hf, <- Hg. apply RiemannInt_P19. apply Hab. apply Heq. Qed.
imports: Reals RiemannInt RIneq Lra R_sqr MyRfunctions