Documentation

Mathlib.MeasureTheory.Measure.Typeclasses.NoAtoms

Measures having no atoms #

A measure μ has no atoms if the measure of each singleton is zero.

TODO #

Should NoAtoms be redefined as ∀ s, 0 < μ s → ∃ t ⊆ s, 0 < μ t ∧ μ t < μ s?

class MeasureTheory.NoAtoms {α : Type u_1} {m0 : MeasurableSpace α} (μ : Measure α) :

Measure μ has no atoms if the measure of each singleton is zero.

NB: Wikipedia assumes that for any measurable set s with positive μ-measure, there exists a measurable t ⊆ s such that 0 < μ t < μ s. While this implies μ {x} = 0, the converse is not true.

  • measure_singleton (x : α) : μ {x} = 0
Instances
theorem Set.Subsingleton.measure_zero {α : Type u_1} {m0 : MeasurableSpace α} {s : Set α} (hs : s.Subsingleton) (μ : MeasureTheory.Measure α) [MeasureTheory.NoAtoms μ] :
μ s = 0
theorem MeasureTheory.Measure.restrict_singleton' {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] {a : α} :
μ.restrict {a} = 0
instance MeasureTheory.Measure.restrict.instNoAtoms {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] (s : Set α) :
theorem Set.Countable.measure_zero {α : Type u_1} {m0 : MeasurableSpace α} {s : Set α} (h : s.Countable) (μ : MeasureTheory.Measure α) [MeasureTheory.NoAtoms μ] :
μ s = 0
theorem Set.Countable.ae_not_mem {α : Type u_1} {m0 : MeasurableSpace α} {s : Set α} (h : s.Countable) (μ : MeasureTheory.Measure α) [MeasureTheory.NoAtoms μ] :
∀ᵐ (x : α) μ, xs
@[simp]
theorem MeasureTheory.restrict_compl_singleton {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] (a : α) :
theorem Set.Finite.measure_zero {α : Type u_1} {m0 : MeasurableSpace α} {s : Set α} (h : s.Finite) (μ : MeasureTheory.Measure α) [MeasureTheory.NoAtoms μ] :
μ s = 0
theorem Finset.measure_zero {α : Type u_1} {m0 : MeasurableSpace α} (s : Finset α) (μ : MeasureTheory.Measure α) [MeasureTheory.NoAtoms μ] :
μ s = 0
theorem MeasureTheory.insert_ae_eq_self {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] (a : α) (s : Set α) :
insert a s =ᶠ[ae μ] s
theorem MeasureTheory.Iio_ae_eq_Iic {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a : α} :
theorem MeasureTheory.Ioi_ae_eq_Ici {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a : α} :
theorem MeasureTheory.Ioo_ae_eq_Ioc {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a b : α} :
theorem MeasureTheory.Ioc_ae_eq_Icc {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a b : α} :
theorem MeasureTheory.Ioo_ae_eq_Ico {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a b : α} :
theorem MeasureTheory.Ioo_ae_eq_Icc {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a b : α} :
theorem MeasureTheory.Ico_ae_eq_Icc {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a b : α} :
theorem MeasureTheory.Ico_ae_eq_Ioc {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a b : α} :
theorem MeasureTheory.restrict_Iio_eq_restrict_Iic {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a : α} :
theorem MeasureTheory.restrict_Ioi_eq_restrict_Ici {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a : α} :
theorem MeasureTheory.restrict_Ioo_eq_restrict_Ioc {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a b : α} :
μ.restrict (Set.Ioo a b) = μ.restrict (Set.Ioc a b)
theorem MeasureTheory.restrict_Ioc_eq_restrict_Icc {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a b : α} :
μ.restrict (Set.Ioc a b) = μ.restrict (Set.Icc a b)
theorem MeasureTheory.restrict_Ioo_eq_restrict_Ico {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a b : α} :
μ.restrict (Set.Ioo a b) = μ.restrict (Set.Ico a b)
theorem MeasureTheory.restrict_Ioo_eq_restrict_Icc {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a b : α} :
μ.restrict (Set.Ioo a b) = μ.restrict (Set.Icc a b)
theorem MeasureTheory.restrict_Ico_eq_restrict_Icc {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a b : α} :
μ.restrict (Set.Ico a b) = μ.restrict (Set.Icc a b)
theorem MeasureTheory.restrict_Ico_eq_restrict_Ioc {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [PartialOrder α] {a b : α} :
μ.restrict (Set.Ico a b) = μ.restrict (Set.Ioc a b)
theorem MeasureTheory.uIoc_ae_eq_interval {α : Type u_1} {m0 : MeasurableSpace α} {μ : Measure α} [NoAtoms μ] [LinearOrder α] {a b : α} :
Ι a b =ᶠ[ae μ] Set.uIcc a b