Proposition double_triangle_alt' {C : double_cat} {x y z : C} (h : x -->h y) (k : y -->h z) : transportf_square (id_v_left _) (id_v_left _) (rassociator_h h _ k ⋆v (id_v_square h ⋆h lunitor_h k)) = runitor_h h ⋆h id_v_square _. Proof. rewrite double_triangle_alt. rewrite transportfb_square. apply idpath. Qed.
Require Import UniMath.MoreFoundations.All. Require Import UniMath.CategoryTheory.Core.Prelude. Require Import UniMath.CategoryTheory.TwoSidedDisplayedCats.TwoSidedDispCat. Require Import UniMath.CategoryTheory.TwoSidedDisplayedCats.Univalence. Require Import UniMath.Bicategories.Core.Bicat. Import Bicat.Notations. Require Import UniMath.Bicategories.DoubleCategories.Core.DoubleCats. Require Import UniMath.Bicategories.DoubleCategories.DerivedLaws.TransportLaws. Require Import UniMath.Bicategories.DoubleCategories.DerivedLaws.Variations. Import TransportSquare.