Definition pb_on_2cell : f /≃₁ β₁ ==> f /≃₁ β₂. Proof. use cell_to_pb_obj. - exact k₁. - exact k₂. - exact pb_on_2cell_homot. Defined.
Require Import UniMath.Foundations.All. Require Import UniMath.MoreFoundations.All. Require Import UniMath.CategoryTheory.Core.Categories. Require Import UniMath.Bicategories.Core.Bicat. Import Bicat.Notations. Require Import UniMath.Bicategories.Core.Unitors. Require Import UniMath.Bicategories.Core.BicategoryLaws. Require Import UniMath.Bicategories.Core.Invertible_2cells. Require Import UniMath.Bicategories.Limits.Pullbacks.