English
iCondIndepFun_iff_iCondIndep: equivalence of independence for functions f,g via comaps of measure spaces.
Русский
Эквивалентость независимости при функциях f,g через компаки сигма-алгебр.
LaTeX
$$$iCondIndepFun(m', hm', f, g, μ) \\iff iCondIndep(m', hm', (\\lambda x. \\mathrm{MeasurableSpace.comap}(f x) (m x)), μ)$$$
Lean4
theorem iCondIndepFun_iff {β : ι → Type*} (m : ∀ x : ι, MeasurableSpace (β x)) (f : ∀ x : ι, Ω → β x)
(hf : ∀ i, Measurable (f i)) (μ : Measure Ω) [IsFiniteMeasure μ] :
iCondIndepFun m' hm' f μ ↔
∀ (s : Finset ι) {g : ι → Set Ω} (_H : ∀ i, i ∈ s → MeasurableSet[(m i).comap (f i)] (g i)),
μ⟦⋂ i ∈ s, g i|m'⟧ =ᵐ[μ] ∏ i ∈ s, (μ⟦g i|m'⟧) :=
by
simp only [iCondIndepFun_iff_iCondIndep]
rw [iCondIndep_iff]
exact fun i ↦ (hf i).comap_le