Hint Extern 1 (Coreflexive (_ /\ _)) =>
eapply rel_inter_corefl_l : typeclass_instances.

(* Specifications: *)
Lemma rel_inter_corefl_r {A} (R1 R2: rel A A):
Coreflexive R2 ->
Coreflexive (R1 /\ R2).