Add Parametric Morphism T : (@PredC T) with signature
@EqPred _ ==> @EqPred _ as predC_morph.

(* Specifications: *)
Lemma sub_orl (r1 r2 : Pred T) : r1 ~> r1 +p r2. Proof. by left. Qed.
Lemma sub_orr (r1 r2 : Pred T) : r2 ~> r1 +p r2. Proof. by right. Qed.
End RelLaws.