Theorem: MeasureTheory.Measure.countable_meas_pos_of_disjoint_iUnion₀
File: Mathlib/MeasureTheory/Measure/Typeclasses.lean

Proof steps:
state_before: α : Type u_1
β : Type u_2
δ : Type u_3
ι✝ : Type u_4
m0 : MeasurableSpace α
inst✝¹ : MeasurableSpace β
μ✝ ν ν₁ ν₂ : Measure α
s t : Set α
ι : Type u_5
x✝ : MeasurableSpace α
μ : Measure α
inst✝ : SFinite μ
As : ι → Set α
As_mble : ∀ (i : ι), NullMeasurableSet (As i) μ
As_disj : Pairwise (AEDisjoint μ on As)
⊢ {i | 0 < μ (As i)}.Countable
state_after: α : Type u_1
β : Type u_2
δ : Type u_3
ι✝ : Type u_4
m0 : MeasurableSpace α
inst✝¹ : MeasurableSpace β
μ✝ ν ν₁ ν₂ : Measure α
s t : Set α
ι : Type u_5
x✝ : MeasurableSpace α
μ : Measure α
inst✝ : SFinite μ
As : ι → Set α
As_mble : ∀ (i : ι), NullMeasurableSet (As i) (sum (sFiniteSeq μ))
As_disj : Pairwise (AEDisjoint (sum (sFiniteSeq μ)) on As)
⊢ {i | 0 < (sum (sFiniteSeq μ)) (As i)}.Countable
tactic: rw [← sum_sFiniteSeq μ] at As_disj As_mble ⊢
state_before: α : Type u_1
β : Type u_2
δ : Type u_3
ι✝ : Type u_4
m0 : MeasurableSpace α
inst✝¹ : MeasurableSpace β
μ✝ ν ν₁ ν₂ : Measure α
s t : Set α
ι : Type u_5
x✝ : MeasurableSpace α
μ : Measure α
inst✝ : SFinite μ
As : ι → Set α
As_mble : ∀ (i : ι), NullMeasurableSet (As i) (sum (sFiniteSeq μ))
As_disj : Pairwise (AEDisjoint (sum (sFiniteSeq μ)) on As)
obs : {i | 0 < (sum (sFiniteSeq μ)) (As i)} ⊆ ⋃ n, {i | 0 < (sFiniteSeq μ n) (As i)}
⊢ {i | 0 < (sum (sFiniteSeq μ)) (As i)}.Countable
state_after: α : Type u_1
β : Type u_2
δ : Type u_3
ι✝ : Type u_4
m0 : MeasurableSpace α
inst✝¹ : MeasurableSpace β
μ✝ ν ν₁ ν₂ : Measure α
s t : Set α
ι : Type u_5
x✝ : MeasurableSpace α
μ : Measure α
inst✝ : SFinite μ
As : ι → Set α
As_mble : ∀ (i : ι), NullMeasurableSet (As i) (sum (sFiniteSeq μ))
As_disj : Pairwise (AEDisjoint (sum (sFiniteSeq μ)) on As)
obs : {i | 0 < (sum (sFiniteSeq μ)) (As i)} ⊆ ⋃ n, {i | 0 < (sFiniteSeq μ n) (As i)}
⊢ (⋃ n, {i | 0 < (sFiniteSeq μ n) (As i)}).Countable
tactic: apply Countable.mono obs
state_before: α : Type u_1
β : Type u_2
δ : Type u_3
ι✝ : Type u_4
m0 : MeasurableSpace α
inst✝¹ : MeasurableSpace β
μ✝ ν ν₁ ν₂ : Measure α
s t : Set α
ι : Type u_5
x✝ : MeasurableSpace α
μ : Measure α
inst✝ : SFinite μ
As : ι → Set α
As_mble : ∀ (i : ι), NullMeasurableSet (As i) (sum (sFiniteSeq μ))
As_disj : Pairwise (AEDisjoint (sum (sFiniteSeq μ)) on As)
obs : {i | 0 < (sum (sFiniteSeq μ)) (As i)} ⊆ ⋃ n, {i | 0 < (sFiniteSeq μ n) (As i)}
⊢ (⋃ n, {i | 0 < (sFiniteSeq μ n) (As i)}).Countable
state_after: α : Type u_1
β : Type u_2
δ : Type u_3
ι✝ : Type u_4
m0 : MeasurableSpace α
inst✝¹ : MeasurableSpace β
μ✝ ν ν₁ ν₂ : Measure α
s t : Set α
ι : Type u_5
x✝ : MeasurableSpace α
μ : Measure α
inst✝ : SFinite μ
As : ι → Set α
As_mble : ∀ (i : ι), NullMeasurableSet (As i) (sum (sFiniteSeq μ))
As_disj : Pairwise (AEDisjoint (sum (sFiniteSeq μ)) on As)
obs : {i | 0 < (sum (sFiniteSeq μ)) (As i)} ⊆ ⋃ n, {i | 0 < (sFiniteSeq μ n) (As i)}
n : ℕ
⊢ {i | 0 < (sFiniteSeq μ n) (As i)}.Countable
tactic: refine countable_iUnion fun n ↦ ?_
state_before: α : Type u_1
β : Type u_2
δ : Type u_3
ι✝ : Type u_4
m0 : MeasurableSpace α
inst✝¹ : MeasurableSpace β
μ✝ ν ν₁ ν₂ : Measure α
s t : Set α
ι : Type u_5
x✝ : MeasurableSpace α
μ : Measure α
inst✝ : SFinite μ
As : ι → Set α
As_mble : ∀ (i : ι), NullMeasurableSet (As i) (sum (sFiniteSeq μ))
As_disj : Pairwise (AEDisjoint (sum (sFiniteSeq μ)) on As)
obs : {i | 0 < (sum (sFiniteSeq μ)) (As i)} ⊆ ⋃ n, {i | 0 < (sFiniteSeq μ n) (As i)}
n : ℕ
⊢ {i | 0 < (sFiniteSeq μ n) (As i)}.Countable
state_after: case As_mble
α : Type u_1
β : Type u_2
δ : Type u_3
ι✝ : Type u_4
m0 : MeasurableSpace α
inst✝¹ : MeasurableSpace β
μ✝ ν ν₁ ν₂ : Measure α
s t : Set α
ι : Type u_5
x✝ : MeasurableSpace α
μ : Measure α
inst✝ : SFinite μ
As : ι → Set α
As_mble : ∀ (i : ι), NullMeasurableSet (As i) (sum (sFiniteSeq μ))
As_disj : Pairwise (AEDisjoint (sum (sFiniteSeq μ)) on As)
obs : {i | 0 < (sum (sFiniteSeq μ)) (As i)} ⊆ ⋃ n, {i | 0 < (sFiniteSeq μ n) (As i)}
n : ℕ
⊢ ∀ (i : ι), NullMeasurableSet (As i) (sFiniteSeq μ n)

case As_disj
α : Type u_1
β : Type u_2
δ : Type u_3
ι✝ : Type u_4
m0 : MeasurableSpace α
inst✝¹ : MeasurableSpace β
μ✝ ν ν₁ ν₂ : Measure α
s t : Set α
ι : Type u_5
x✝ : MeasurableSpace α
μ : Measure α
inst✝ : SFinite μ
As : ι → Set α
As_mble : ∀ (i : ι), NullMeasurableSet (As i) (sum (sFiniteSeq μ))
As_disj : Pairwise (AEDisjoint (sum (sFiniteSeq μ)) on As)
obs : {i | 0 < (sum (sFiniteSeq μ)) (As i)} ⊆ ⋃ n, {i | 0 < (sFiniteSeq μ n) (As i)}
n : ℕ
⊢ Pairwise (AEDisjoint (sFiniteSeq μ n) on As)

case Union_As_finite
α : Type u_1
β : Type u_2
δ : Type u_3
ι✝ : Type u_4
m0 : MeasurableSpace α
inst✝¹ : MeasurableSpace β
μ✝ ν ν₁ ν₂ : Measure α
s t : Set α
ι : Type u_5
x✝ : MeasurableSpace α
μ : Measure α
inst✝ : SFinite μ
As : ι → Set α
As_mble : ∀ (i : ι), NullMeasurableSet (As i) (sum (sFiniteSeq μ))
As_disj : Pairwise (AEDisjoint (sum (sFiniteSeq μ)) on As)
obs : {i | 0 < (sum (sFiniteSeq μ)) (As i)} ⊆ ⋃ n, {i | 0 < (sFiniteSeq μ n) (As i)}
n : ℕ
⊢ (sFiniteSeq μ n) (⋃ i, As i) ≠ ⊤
tactic: apply countable_meas_pos_of_disjoint_of_meas_iUnion_ne_top₀