proposition: Proposition double_triangle {C : double_cat} {x y z : C} (h : x -->h y) (k : y -->h z) : lassociator_h h _ k ⋆v (runitor_h h ⋆h id_v_square _) = transportb_square (id_v_left _) (id_v_left _) (id_v_square h ⋆h lunitor_h k).
proof: Proof. exact (pr12 (pr222 (pr222 C)) x y z h k). Qed.
imports: UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.TwoSidedDisplayedCats.TwoSidedDispCat UniMath.CategoryTheory.TwoSidedDisplayedCats.Isos UniMath.CategoryTheory.TwoSidedDisplayedCats.Univalence UniMath.Bicategories.Core.Examples.BicatOfUnivCats UniMath.Bicategories.DoubleCategories.Basics.DoubleCategoryBasics