proposition: Lemma is_iso_isEpi {x y : C} (f : x --> y) (H : is_z_isomorphism f) : isEpi f.
proof: Proof. apply make_isEpi. intros z g h X. apply (pre_comp_with_z_iso_is_inj H). exact X. Qed.
imports: UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.FunctorCategory UniMath.CategoryTheory.Subcategory.Core UniMath.CategoryTheory.Core.Functors