∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] {Y Z : C} {P : CategoryTheory.Subobject Y} (f : Z ⟶ Y)
  (motive : (CategoryTheory.Subobject.representative.obj P).Factors f → Prop)
  (x : (CategoryTheory.Subobject.representative.obj P).Factors f),
  (∀ (u : Z ⟶ (CategoryTheory.Subobject.representative.obj P).obj.left)
      (hu : CategoryTheory.CategoryStruct.comp u (CategoryTheory.Subobject.representative.obj P).arrow = f), motive ⋯) →
    motive x