∀ {X Y : TopCat} {f : X ⟶ Y} (hf : Topology.IsInducing ⇑(CategoryTheory.ConcreteCategory.hom f))
  {X_1 Y_1 Z : TopologicalSpace.Opens ↑X} (f_1 : X_1 ⟶ Y_1) (g : Y_1 ⟶ Z),
  CategoryTheory.homOfLE ⋯ = CategoryTheory.CategoryStruct.comp (CategoryTheory.homOfLE ⋯) (CategoryTheory.homOfLE ⋯)