∀ {C : Type u₁} [inst : CategoryTheory.Category.{v₁, u₁} C] [inst_1 : CategoryTheory.MonoidalCategory C]
  [inst_2 : CategoryTheory.BraidedCategory C] (X Y Z : CategoryTheory.Mon C),
  (CategoryTheory.MonoidalCategoryStruct.associator X Y Z).inv.hom =
    (CategoryTheory.MonoidalCategoryStruct.associator X.X Y.X Z.X).inv