English
The primed version asserts the same composition rule in a slightly different form: g ∘ f is AEMeasurable when hg is measurable and hf is AEMeasurable.
Русский
Уточненная версия утверждает ту же самую формулу композиции: AEMeasurable(g∘f) когда hg измерима, hf AEMeasurable.
LaTeX
$$$\text{Measurable}(g) \rightarrow \mathrm{AEMeasurable}(f)\mu \rightarrow \mathrm{AEMeasurable}(\lambda x. g(f(x)))\mu$$$
Lean4
@[fun_prop, measurability]
theorem comp_aemeasurable' [MeasurableSpace δ] {f : α → δ} {g : δ → β} (hg : Measurable g) (hf : AEMeasurable f μ) :
AEMeasurable (fun x ↦ g (f x)) μ :=
Measurable.comp_aemeasurable hg hf