English
In a Hausdorff magma with continuous multiplication, the centralizer of any set is closed.
Русский
В несмещенной магме с непрерывным умножением центральизатор любого множества замкнут.
LaTeX
$$$IsClosed(centralizer(s))$$$
Lean4
/-- In a Hausdorff magma with continuous multiplication, the centralizer of any set is closed. -/
theorem isClosed_centralizer {M : Type*} (s : Set M) [Mul M] [TopologicalSpace M] [ContinuousMul M] [T2Space M] :
IsClosed (centralizer s) := by
rw [centralizer, setOf_forall]
refine isClosed_sInter ?_
rintro - ⟨m, ht, rfl⟩
refine isClosed_imp (by simp) <| isClosed_eq ?_ ?_
all_goals fun_prop