Lemma runitor_triangle {a b c: C} (f : C⟦a, b⟧) (g : C⟦b, c⟧) : rassociator f g (identity c) • (f ◃ runitor g) = runitor (f · g). Proof. apply rwhisker_id_inj. etrans. 2: apply runitor_rwhisker_rwhisker. apply pathsinv0, rwhisker_vcomp. 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.Examples.OpMorBicat. Require Import UniMath.Bicategories.Core.Examples.OpCellBicat.