English
A continuous function whose support is contained in a compact set is strongly measurable.
Русский
Непрерывная функция с опорой, contained in компакт, сильно измерима.
LaTeX
$$$\text{Continuous}(f) \land \text{IsCompact}(k) \land \mathrm{mulSupport}(f) \subseteq k \Rightarrow \mathrm{StronglyMeasurable}(f)$$$
Lean4
/-- A continuous function whose support is contained in a compact set is strongly measurable. -/
@[to_additive]
theorem _root_.Continuous.stronglyMeasurable_of_mulSupport_subset_isCompact [MeasurableSpace α] [TopologicalSpace α]
[OpensMeasurableSpace α] [MeasurableSpace β] [TopologicalSpace β] [PseudoMetrizableSpace β] [BorelSpace β] [One β]
{f : α → β} (hf : Continuous f) {k : Set α} (hk : IsCompact k) (h'f : mulSupport f ⊆ k) : StronglyMeasurable f :=
by
letI : PseudoMetricSpace β := pseudoMetrizableSpacePseudoMetric β
rw [stronglyMeasurable_iff_measurable_separable]
exact ⟨hf.measurable, (isCompact_range_of_mulSupport_subset_isCompact hf hk h'f).isSeparable⟩