Definition isPullback_iso_comma : isPullback sqr₃. Proof. intros w h₁ h₂ p. use iscontraprop1. - apply isPullback_iso_comma_unique. - simple refine (_ ,, _ ,, _). + exact (isPullback_iso_comma_mor h₁ h₂ p). + exact (isPullback_iso_comma_mor_pr1 h₁ h₂ p). + exact (isPullback_iso_comma_mor_pr2 h₁ h₂ p). Defined.
Require Import UniMath.Foundations.All. Require Import UniMath.MoreFoundations.All. Require Import UniMath.CategoryTheory.Core.Categories. Require Import UniMath.CategoryTheory.Core.Functors. Require Import UniMath.CategoryTheory.Core.Isos. Require Import UniMath.CategoryTheory.Core.NaturalTransformations. Require Import UniMath.CategoryTheory.IsoCommaCategory. Require Import UniMath.CategoryTheory.Limits.Terminal. Require Import UniMath.CategoryTheory.Limits.BinProducts. Require Import UniMath.CategoryTheory.Limits.Pullbacks. Require Import UniMath.CategoryTheory.Limits.Initial. Require Import UniMath.CategoryTheory.Limits.BinCoproducts. Require Import UniMath.CategoryTheory.Limits.Preservation.