English
Two sets u and v in a measurable space are measurably separable if there exists a measurable set containing u and disjoint from v.
Русский
Две множества u и v в измеримом пространстве называются измеримо разделимыми, если существует измеримое множество, содержащее u и дискредитирующее v.
LaTeX
$$$\exists u, s \subseteq u \wedge Disjoint\ v\ u \wedge MeasurableSet\ u.$$$
Lean4
/-- Two sets `u` and `v` in a measurable space are measurably separable if there
exists a measurable set containing `u` and disjoint from `v`.
This is mostly interesting for Borel-separable sets. -/
def MeasurablySeparable {α : Type*} [MeasurableSpace α] (s t : Set α) : Prop :=
∃ u, s ⊆ u ∧ Disjoint t u ∧ MeasurableSet u