English
Assume α is a complete space and f: α → β is K-antilipschitz with constant K, uniformly continuous, and α is complete. Then the image of α under f is a closed subset of β.
Русский
Пусть α — полное пространство, f: α → β — K‑антлипшицивна и равномерно непрерывна. Тогда образ f(α) является замкнутым подмножеством β.
LaTeX
$$$ \text{IsClosed}(\operatorname{range} f) \\text{ under } [\text{CompleteSpace } \alpha], hf : \operatorname{AntilipschitzWith} K f, hfc : \text{UniformContinuous } f$$$
Lean4
theorem isClosed_range {α β : Type*} [PseudoEMetricSpace α] [EMetricSpace β] [CompleteSpace α] {f : α → β} {K : ℝ≥0}
(hf : AntilipschitzWith K f) (hfc : UniformContinuous f) : IsClosed (range f) :=
(hf.isComplete_range hfc).isClosed