Hint Extern 0 (RElim ⊥ _ _ _ _) =>
eapply rel_bot_relim : typeclass_instances.
Definition rel_top {A B}: rel A B :=
fun x y => True.
Notation "⊤" := rel_top : rel_scope.

Lemma rel_top_rintro {A B} (x: A) (y: B):
RIntro True ⊤ x y.