Hint Extern 1 (RElim (forall_rel _) _ _ _ _) =>
eapply forall_relim : typeclass_instances.
(** ** Inverse relation *)
(** We use [flip] as our inversion relator. To this end we characterize its variance and introduce an [RElim] rule. *)
Global Instance flip_subrel {A B}:
Monotonic (@flip A B Prop) (subrel ++> subrel).
Global Instance flip_subrel_params:
Params (@flip) 3.

Lemma flip_rintro {A B} (R: rel A B) m n:
RIntro (R n m) (flip R) m n.