English
If i ∈ S and s is measurable with respect to m_i, then s belongs to piiUnionInter (λ n, {s | MeasurableSet[m n] s}) S.
Русский
Если i ∈ S и множество s измеримо относительно пространства m_i, то s принадлежит piiUnionInter (λ n, {s | MeasurableSet[m n] s}) S.
LaTeX
$$$\text{hiS : } i \in S \; \rightarrow \; s \in \mathrm{piiUnionInter}(\lambda n, \{s \mid MeasurableSet[m n] s\}) S$$$
Lean4
theorem mem_piiUnionInter_of_measurableSet (m : ι → MeasurableSpace α) {S : Set ι} {i : ι} (hiS : i ∈ S) (s : Set α)
(hs : MeasurableSet[m i] s) : s ∈ piiUnionInter (fun n => {s | MeasurableSet[m n] s}) S :=
subset_piiUnionInter hiS hs