Definition Cokernel_up_to_iso2_eq {x y z : C} (f1 : x --> z) (f2 : y --> z) (h : z_iso y x) (H : h · f1 = f2) (CK : Cokernel Z f1) : f2 · CokernelArrow CK = ZeroArrow Z y CK.
Require Import UniMath.Foundations.PartD. Require Import UniMath.Foundations.Propositions. Require Import UniMath.Foundations.Sets. Require Import UniMath.CategoryTheory.Core.Categories. Require Import UniMath.CategoryTheory.Core.Isos. Require Import UniMath.CategoryTheory.Epis. Require Import UniMath.CategoryTheory.Limits.Coequalizers. Require Import UniMath.CategoryTheory.Limits.Zero. - exact (ZeroArrowFrom w). - intros y X. cbn in X. use ArrowsFromZero.