Definition has_dependent_sums : UU := ∑ (L : ∏ (x y : C) (f : x --> y), dependent_sum f), ∏ (w x y z : C) (f : x --> w) (g : y --> w) (h : z --> y) (k : z --> x) (p : k · f = h · g) (H : isPullback p), left_beck_chevalley f g h k p (L _ _ f) (L _ _ h).
Require Import UniMath.Foundations.All. Require Import UniMath.MoreFoundations.All. Require Import UniMath.CategoryTheory.Core.Prelude. Require Import UniMath.CategoryTheory.Adjunctions.Core. Require Import UniMath.CategoryTheory.DisplayedCats.Core. Require Import UniMath.CategoryTheory.DisplayedCats.Univalence. Require Import UniMath.CategoryTheory.DisplayedCats.Functors. Require Import UniMath.CategoryTheory.DisplayedCats.Fibrations. Require Import UniMath.CategoryTheory.DisplayedCats.Fiber. Require Import UniMath.CategoryTheory.whiskering. Require Import UniMath.CategoryTheory.Limits.Pullbacks.