English
If g is AEMeasurable on α → Π a, X a, then for each a, the map x ↦ g(x)(a) is AEMeasurable with respect to μ.
Русский
Если g AEMeasurable на α → Π a, X a, то для каждого a карта x ↦ g(x)(a) является AEMeasurable по отношению к μ.
LaTeX
$$$\mathrm{AEMeasurable}\ g\ \mu \rightarrow \forall a, \mathrm{AEMeasurable}(\lambda x. g\,x\,a)\ \mu$$$
Lean4
@[measurability]
protected theorem eval {g : α → Π a, X a} (hg : AEMeasurable g μ) (a : δ) : AEMeasurable (fun x ↦ g x a) μ :=
by
use fun x ↦ hg.mk g x a, hg.measurable_mk.eval
exact hg.ae_eq_mk.mono fun _ h ↦ congrFun h _