Hint Extern 0 (RIntro _ (pointwise_relation _ _) _ _) =>
eapply pointwise_relation_rintro : typeclass_instances.

Lemma pointwise_relation_relim {A B} (R: relation B) f g a P Q:
RElim R (f a) (g a) P Q ->
RElim (pointwise_relation A R) f g P Q.