Hint Extern 0 (RExists _ subrel (_ /\ _)%rel _) =>
eapply rel_inter_subrel_rexists_r : typeclass_instances.

Lemma rel_inter_glb {A B} (R R1 R2: rel A B):
RIntro (subrel R R1 /\ subrel R R2) subrel R (R1 /\ R2)%rel.