Definition is_invertible_2cell {C : prebicat_data} {a b : C} {f g : a --> b} (η : f ==> g) : UU := ∑ φ : g ==> f, η • φ = id2 f × φ • η = id2 g.
Require Import UniMath.Foundations.All. Require Import UniMath.MoreFoundations.All. Require Import UniMath.CategoryTheory.Core.Categories. Require Import UniMath.CategoryTheory.Core.Isos. Require Import UniMath.CategoryTheory.Core.Functors. Require Import UniMath.CategoryTheory.Core.NaturalTransformations. Require Import UniMath.CategoryTheory.PrecategoryBinProduct.