English
A locally Lipschitz function is continuous.
Русский
Локально липшицева функция непрерывна.
LaTeX
$$$\\forall f,\\ LocallyLipschitz f\\Rightarrow Continuous f$$$
Lean4
/-- A locally Lipschitz function is continuous. (The converse is false: for example,
$x ↦ \sqrt{x}$ is continuous, but not locally Lipschitz at 0.) -/
protected theorem continuous {f : α → β} (hf : LocallyLipschitz f) : Continuous f :=
by
rw [continuous_iff_continuousAt]
intro x
rcases (hf x) with ⟨K, t, ht, hK⟩
exact (hK.continuousOn).continuousAt ht