(* equlaity *)
Section pulb_setoid_def.
Variable a b : PULB_ob.
Definition Equal_PULB_mor (f g : PULB_mor a b) := True.

Lemma Equal_PULB_mor_equiv : Equivalence Equal_PULB_mor.
Canonical Structure PULB_mor_setoid := Build_Setoid Equal_PULB_mor_equiv.