Definition Prod_Hom' := SPROD (Ob_l u --> Ob_l t) (Ob_r u --> Ob_r t).
Definition Build1_Pmor :
(Ob_l u --> Ob_l t) -> (Ob_r u --> Ob_r t) -> Prod_Hom := Build_Pmor.
End pmor_setoid_def.
(* composition *)
Definition Comp_Pmor (a b c : POb) (f : Prod_Hom a b)
(g : Prod_Hom b c) := Build_Pmor (Hom_l f o Hom_l g) (Hom_r f o Hom_r g).

Lemma Idr_PROD : Idr_law Comp_PROD Id_PROD.
Canonical Structure PROD := Build_Category Assoc_PROD Idl_PROD Idr_PROD.