∀ {C : Type u_1} [inst : CategoryTheory.Category.{u_2, u_1} C] {B A : C} (X : CategoryTheory.Subobject B) (f : A ⟶ B)
  [inst_1 : CategoryTheory.Mono f], X = CategoryTheory.Subobject.mk f → X ≤ CategoryTheory.Subobject.mk f