Lemma triangle_l {X Y Z : C} (g : C⟦Y,Z⟧) (f : C⟦X,Y⟧) : lunitor g ⋆⋆ id₂ f o rassociator _ _ _ = id₂ g ⋆⋆ runitor f. Proof. rewrite triangle_r. rewrite vassocr. rewrite <- inverse_of_assoc. rewrite vcomp_linv. rewrite id2_left. apply idpath. Qed.
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.Invertible_2cells. Require Import UniMath.Bicategories.Core.Unitors.