Theorem: MeasureTheory.tendsto_measure_of_ae_tendsto_indicator
File: Mathlib/MeasureTheory/Integral/Lebesgue.lean

Proof steps:
state_before: α✝ : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m m0 : MeasurableSpace α✝
α : Type u_5
inst✝¹ : MeasurableSpace α
A : Set α
ι : Type u_6
L : Filter ι
inst✝ : L.IsCountablyGenerated
As : ι → Set α
μ : Measure α
A_mble : MeasurableSet A
As_mble : ∀ (i : ι), MeasurableSet (As i)
B : Set α
B_mble : MeasurableSet B
B_finmeas : μ B ≠ ⊤
As_le_B : ∀ᶠ (i : ι) in L, As i ⊆ B
h_lim : ∀ᵐ (x : α) ∂μ, ∀ᶠ (i : ι) in L, x ∈ As i ↔ x ∈ A
⊢ Tendsto (fun i => μ (As i)) L (𝓝 (μ A))
state_after: α✝ : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m m0 : MeasurableSpace α✝
α : Type u_5
inst✝¹ : MeasurableSpace α
A : Set α
ι : Type u_6
L : Filter ι
inst✝ : L.IsCountablyGenerated
As : ι → Set α
μ : Measure α
A_mble : MeasurableSet A
As_mble : ∀ (i : ι), MeasurableSet (As i)
B : Set α
B_mble : MeasurableSet B
B_finmeas : μ B ≠ ⊤
As_le_B : ∀ᶠ (i : ι) in L, As i ⊆ B
h_lim : ∀ᵐ (x : α) ∂μ, ∀ᶠ (i : ι) in L, x ∈ As i ↔ x ∈ A
⊢ Tendsto (fun i => ∫⁻ (a : α), (As i).indicator 1 a ∂μ) L (𝓝 (∫⁻ (a : α), A.indicator 1 a ∂μ))
tactic: simp_rw [← MeasureTheory.lintegral_indicator_one A_mble,
           ← MeasureTheory.lintegral_indicator_one (As_mble _)]
state_before: α✝ : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m m0 : MeasurableSpace α✝
α : Type u_5
inst✝¹ : MeasurableSpace α
A : Set α
ι : Type u_6
L : Filter ι
inst✝ : L.IsCountablyGenerated
As : ι → Set α
μ : Measure α
A_mble : MeasurableSet A
As_mble : ∀ (i : ι), MeasurableSet (As i)
B : Set α
B_mble : MeasurableSet B
B_finmeas : μ B ≠ ⊤
As_le_B : ∀ᶠ (i : ι) in L, As i ⊆ B
h_lim : ∀ᵐ (x : α) ∂μ, ∀ᶠ (i : ι) in L, x ∈ As i ↔ x ∈ A
⊢ Tendsto (fun i => ∫⁻ (a : α), (As i).indicator 1 a ∂μ) L (𝓝 (∫⁻ (a : α), A.indicator 1 a ∂μ))
state_after: case refine_1
α✝ : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m m0 : MeasurableSpace α✝
α : Type u_5
inst✝¹ : MeasurableSpace α
A : Set α
ι : Type u_6
L : Filter ι
inst✝ : L.IsCountablyGenerated
As : ι → Set α
μ : Measure α
A_mble : MeasurableSet A
As_mble : ∀ (i : ι), MeasurableSet (As i)
B : Set α
B_mble : MeasurableSet B
B_finmeas : μ B ≠ ⊤
As_le_B : ∀ᶠ (i : ι) in L, As i ⊆ B
h_lim : ∀ᵐ (x : α) ∂μ, ∀ᶠ (i : ι) in L, x ∈ As i ↔ x ∈ A
⊢ ∀ (x : ι), Measurable ((As x).indicator 1)

case refine_2
α✝ : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m m0 : MeasurableSpace α✝
α : Type u_5
inst✝¹ : MeasurableSpace α
A : Set α
ι : Type u_6
L : Filter ι
inst✝ : L.IsCountablyGenerated
As : ι → Set α
μ : Measure α
A_mble : MeasurableSet A
As_mble : ∀ (i : ι), MeasurableSet (As i)
B : Set α
B_mble : MeasurableSet B
B_finmeas : μ B ≠ ⊤
As_le_B : ∀ᶠ (i : ι) in L, As i ⊆ B
h_lim : ∀ᵐ (x : α) ∂μ, ∀ᶠ (i : ι) in L, x ∈ As i ↔ x ∈ A
⊢ ∀ᶠ (n : ι) in L, ∀ᵐ (a : α) ∂μ, (As n).indicator 1 a ≤ B.indicator 1 a

case refine_3
α✝ : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m m0 : MeasurableSpace α✝
α : Type u_5
inst✝¹ : MeasurableSpace α
A : Set α
ι : Type u_6
L : Filter ι
inst✝ : L.IsCountablyGenerated
As : ι → Set α
μ : Measure α
A_mble : MeasurableSet A
As_mble : ∀ (i : ι), MeasurableSet (As i)
B : Set α
B_mble : MeasurableSet B
B_finmeas : μ B ≠ ⊤
As_le_B : ∀ᶠ (i : ι) in L, As i ⊆ B
h_lim : ∀ᵐ (x : α) ∂μ, ∀ᶠ (i : ι) in L, x ∈ As i ↔ x ∈ A
⊢ ∫⁻ (a : α), B.indicator 1 a ∂μ ≠ ⊤

case refine_4
α✝ : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m m0 : MeasurableSpace α✝
α : Type u_5
inst✝¹ : MeasurableSpace α
A : Set α
ι : Type u_6
L : Filter ι
inst✝ : L.IsCountablyGenerated
As : ι → Set α
μ : Measure α
A_mble : MeasurableSet A
As_mble : ∀ (i : ι), MeasurableSet (As i)
B : Set α
B_mble : MeasurableSet B
B_finmeas : μ B ≠ ⊤
As_le_B : ∀ᶠ (i : ι) in L, As i ⊆ B
h_lim : ∀ᵐ (x : α) ∂μ, ∀ᶠ (i : ι) in L, x ∈ As i ↔ x ∈ A
⊢ ∀ᵐ (a : α) ∂μ, Tendsto (fun n => (As n).indicator 1 a) L (𝓝 (A.indicator 1 a))
tactic: refine tendsto_lintegral_filter_of_dominated_convergence (B.indicator (1 : α → ℝ≥0∞))
          (eventually_of_forall ?_) ?_ ?_ ?_