Documentation

Mathlib.MeasureTheory.Measure.Count

Counting measure #

In this file we define the counting measure MeasurTheory.Measure.count as MeasureTheory.Measure.sum MeasureTheory.Measure.dirac and prove basic properties of this measure.

Counting measure on any measurable space.

Equations
Instances For
    @[simp]
    theorem MeasureTheory.Measure.count_ne_zero'' {α : Type u_1} [MeasurableSpace α] [Nonempty α] :
    MeasureTheory.Measure.count 0
    theorem MeasureTheory.Measure.le_count_apply {α : Type u_1} [MeasurableSpace α] {s : Set α} :
    ∑' (x : s), 1 MeasureTheory.Measure.count s
    theorem MeasureTheory.Measure.count_apply {α : Type u_1} [MeasurableSpace α] {s : Set α} (hs : MeasurableSet s) :
    MeasureTheory.Measure.count s = ∑' (x : s), 1
    theorem MeasureTheory.Measure.count_empty {α : Type u_1} [MeasurableSpace α] :
    MeasureTheory.Measure.count = 0
    @[simp]
    theorem MeasureTheory.Measure.count_apply_finset' {α : Type u_1} [MeasurableSpace α] {s : Finset α} (s_mble : MeasurableSet s) :
    MeasureTheory.Measure.count s = s.card
    @[simp]
    theorem MeasureTheory.Measure.count_apply_finset {α : Type u_1} [MeasurableSpace α] [MeasurableSingletonClass α] (s : Finset α) :
    MeasureTheory.Measure.count s = s.card
    theorem MeasureTheory.Measure.count_apply_finite' {α : Type u_1} [MeasurableSpace α] {s : Set α} (s_fin : s.Finite) (s_mble : MeasurableSet s) :
    MeasureTheory.Measure.count s = s_fin.toFinset.card
    theorem MeasureTheory.Measure.count_apply_finite {α : Type u_1} [MeasurableSpace α] [MeasurableSingletonClass α] (s : Set α) (hs : s.Finite) :
    MeasureTheory.Measure.count s = hs.toFinset.card
    theorem MeasureTheory.Measure.count_apply_infinite {α : Type u_1} [MeasurableSpace α] {s : Set α} (hs : s.Infinite) :
    MeasureTheory.Measure.count s =

    count measure evaluates to infinity at infinite sets.

    @[simp]
    theorem MeasureTheory.Measure.count_apply_eq_top' {α : Type u_1} [MeasurableSpace α] {s : Set α} (s_mble : MeasurableSet s) :
    MeasureTheory.Measure.count s = s.Infinite
    @[simp]
    theorem MeasureTheory.Measure.count_apply_eq_top {α : Type u_1} [MeasurableSpace α] {s : Set α} [MeasurableSingletonClass α] :
    MeasureTheory.Measure.count s = s.Infinite
    @[simp]
    theorem MeasureTheory.Measure.count_apply_lt_top' {α : Type u_1} [MeasurableSpace α] {s : Set α} (s_mble : MeasurableSet s) :
    MeasureTheory.Measure.count s < s.Finite
    @[simp]
    theorem MeasureTheory.Measure.count_apply_lt_top {α : Type u_1} [MeasurableSpace α] {s : Set α} [MeasurableSingletonClass α] :
    MeasureTheory.Measure.count s < s.Finite
    theorem MeasureTheory.Measure.empty_of_count_eq_zero' {α : Type u_1} [MeasurableSpace α] {s : Set α} (s_mble : MeasurableSet s) (hsc : MeasureTheory.Measure.count s = 0) :
    s =
    theorem MeasureTheory.Measure.empty_of_count_eq_zero {α : Type u_1} [MeasurableSpace α] {s : Set α} [MeasurableSingletonClass α] (hsc : MeasureTheory.Measure.count s = 0) :
    s =
    @[simp]
    theorem MeasureTheory.Measure.count_eq_zero_iff' {α : Type u_1} [MeasurableSpace α] {s : Set α} (s_mble : MeasurableSet s) :
    MeasureTheory.Measure.count s = 0 s =
    @[simp]
    theorem MeasureTheory.Measure.count_eq_zero_iff {α : Type u_1} [MeasurableSpace α] {s : Set α} [MeasurableSingletonClass α] :
    MeasureTheory.Measure.count s = 0 s =
    theorem MeasureTheory.Measure.count_ne_zero' {α : Type u_1} [MeasurableSpace α] {s : Set α} (hs' : s.Nonempty) (s_mble : MeasurableSet s) :
    MeasureTheory.Measure.count s 0
    theorem MeasureTheory.Measure.count_ne_zero {α : Type u_1} [MeasurableSpace α] {s : Set α} [MeasurableSingletonClass α] (hs' : s.Nonempty) :
    MeasureTheory.Measure.count s 0
    @[simp]
    theorem MeasureTheory.Measure.count_singleton' {α : Type u_1} [MeasurableSpace α] {a : α} (ha : MeasurableSet {a}) :
    MeasureTheory.Measure.count {a} = 1
    theorem MeasureTheory.Measure.count_singleton {α : Type u_1} [MeasurableSpace α] [MeasurableSingletonClass α] (a : α) :
    MeasureTheory.Measure.count {a} = 1
    theorem MeasureTheory.Measure.count_injective_image' {α : Type u_1} {β : Type u_2} [MeasurableSpace α] [MeasurableSpace β] {f : βα} (hf : Function.Injective f) {s : Set β} (s_mble : MeasurableSet s) (fs_mble : MeasurableSet (f '' s)) :
    MeasureTheory.Measure.count (f '' s) = MeasureTheory.Measure.count s
    theorem MeasureTheory.Measure.count_injective_image {α : Type u_1} {β : Type u_2} [MeasurableSpace α] [MeasurableSpace β] [MeasurableSingletonClass α] [MeasurableSingletonClass β] {f : βα} (hf : Function.Injective f) (s : Set β) :
    MeasureTheory.Measure.count (f '' s) = MeasureTheory.Measure.count s
    Equations
    • =
    @[simp]
    theorem MeasureTheory.Measure.count_univ {α : Type u_1} [MeasurableSpace α] [Fintype α] :
    MeasureTheory.Measure.count Set.univ = (Fintype.card α)