English
If f,g: β → α are almost everywhere measurable with respect to μ, then the map a ↦ edist(f(a), g(a)) is AEMeasurable with respect to μ.
Русский
Если f,g: β → α — а.е.-измеримы по μ, то a ↦ edist(f(a), g(a)) — а.е.-измеримо по μ.
LaTeX
$$$AEMeasurable f \\mu \\; \\land \\; AEMeasurable g \\mu \\; \\Rightarrow \\; AEMeasurable (\\lambda a. edist (f a) (g a)) \\mu$$$
Lean4
@[measurability, fun_prop]
theorem edist {f g : β → α} {μ : Measure β} (hf : AEMeasurable f μ) (hg : AEMeasurable g μ) :
AEMeasurable (fun a => edist (f a) (g a)) μ :=
(@continuous_edist α _).aemeasurable2 hf hg