proposition: 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: Proof. rewrite double_triangle_alt. rewrite transportfb_square. apply idpath. Qed.
imports: UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Prelude UniMath.CategoryTheory.TwoSidedDisplayedCats.TwoSidedDispCat UniMath.CategoryTheory.TwoSidedDisplayedCats.Univalence UniMath.Bicategories.Core.Bicat UniMath.Bicategories.DoubleCategories.Core.DoubleCats UniMath.Bicategories.DoubleCategories.DerivedLaws.TransportLaws UniMath.Bicategories.DoubleCategories.DerivedLaws.Variations