Lemma is_iso_from_is_z_iso {C : precategory} {a b : C} (f: a --> b) : is_z_isomorphism f -> is_iso f. Proof. intro H. apply (is_iso_qinv _ (pr1 H)). apply (pr2 H). Defined.
Require Import UniMath.Foundations.PartA. Require Import UniMath.Foundations.Propositions. Require Import UniMath.Foundations.Sets. Require Import UniMath.MoreFoundations.Tactics. Require Import UniMath.CategoryTheory.Core.Categories.