Hint Extern 0 (RExists _ (_ /\ _) _ _) =>
eapply rel_inter_rexists : typeclass_instances.

(* Specifications: *)
Lemma rel_inter_subrel_rexists_l {A B} (R1 R2 R: rel A B):
RExists (subrel R1 R) subrel (R1 /\ R2)%rel R.