Definition triangle {C : category} {tu : tensor_unit C} (ua : unitors_associator tu) : UU := ∏ (x y : C), (pr1 ass^{ua} x I_{tu} y) · ((identity x) ⊗^{tu} (pr1 lu^{ua} y)) = (pr1 ru^{ua} x) ⊗^{tu} (identity y).
Require Import UniMath.Foundations.All. Require Import UniMath.MoreFoundations.All. Require Import UniMath.CategoryTheory.Core.Categories. Require Import UniMath.CategoryTheory.Core.Functors. Require Import UniMath.CategoryTheory.Core.NaturalTransformations. Require Import UniMath.CategoryTheory.Core.Isos. Import TensorNotation. Import TensorUnitNotation. Import TensorNotation. Import TensorUnitNotation. Import TensorNotation. Import TensorUnitNotation. Import TensorNotation. Import TensorUnitNotation. Import UnitorsAssociatorNotation. Import TensorNotation. Import TensorUnitNotation. Import UnitorsAssociatorNotation.