English
Restriction commutes with toOuterMeasure: (μ|s).toOuterMeasure = OuterMeasure.restrict s μ.toOuterMeasure.
Русский
Ограничение и переход к внешней мере коммутируют: (μ|s).toOuterMeasure = OuterMeasure.restrict s μ.toOuterMeasure.
LaTeX
$$$(\mu|s).toOuterMeasure = OuterMeasure.restrict(s,\mu.toOuterMeasure).$$$
Lean4
theorem restrict_apply₀' (hs : NullMeasurableSet s μ) : μ.restrict s t = μ (t ∩ s) := by
rw [← restrict_congr_set hs.toMeasurable_ae_eq, restrict_apply' (measurableSet_toMeasurable _ _),
measure_congr ((ae_eq_refl t).inter hs.toMeasurable_ae_eq)]