English
Adding the empty set to the generating family does not change the generated topology.
Русский
Добавление пустого множества к порождающей семье не меняет порожденную топологию.
LaTeX
$$@[simp] theorem generateFrom_insert_empty {α : Type*} {s : Set (Set α)} : generateFrom (insert ∅ s) = generateFrom s$$
Lean4
@[simp]
theorem generateFrom_insert_empty {α : Type*} {s : Set (Set α)} : generateFrom (insert ∅ s) = generateFrom s :=
by
rw [← sUnion_empty]
exact generateFrom_insert_of_generateOpen (.sUnion ∅ (fun s_1 a ↦ False.elim a))