English
The distance on the completion is a continuous extension; in particular, for f,g : β → Completion α which are continuous, the map x ↦ dist (f x) (g x) is continuous.
Русский
Расстояние на завершении является непрерывным продолжением; если f,g : β → Completion α непрерывны, то x ↦ dist(f x, g x) непрерывно.
LaTeX
$$$\text{Continuous}\, f \to \text{Continuous}\, g \; \Rightarrow \; \text{Continuous}\, (\lambda x, \operatorname{dist}(f x)(g x))$$$
Lean4
/-- The new distance is continuous. -/
protected theorem continuous_dist [TopologicalSpace β] {f g : β → Completion α} (hf : Continuous f)
(hg : Continuous g) : Continuous fun x ↦ dist (f x) (g x) :=
Completion.uniformContinuous_dist.continuous.comp (hf.prodMk hg :)