Theorem: MeasureTheory.LocallyIntegrableOn.aestronglyMeasurable
File: Mathlib/MeasureTheory/Function/LocallyIntegrable.lean

Proof steps:
state_before: X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
R : Type u_5
inst✝⁶ : MeasurableSpace X
inst✝⁵ : TopologicalSpace X
inst✝⁴ : MeasurableSpace Y
inst✝³ : TopologicalSpace Y
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedAddCommGroup F
f g : X → E
μ : Measure X
s : Set X
inst✝ : SecondCountableTopology X
hf : LocallyIntegrableOn f s μ
⊢ AEStronglyMeasurable f (μ.restrict s)
state_after: case intro.intro.intro
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
R : Type u_5
inst✝⁶ : MeasurableSpace X
inst✝⁵ : TopologicalSpace X
inst✝⁴ : MeasurableSpace Y
inst✝³ : TopologicalSpace Y
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedAddCommGroup F
f g : X → E
μ : Measure X
s : Set X
inst✝ : SecondCountableTopology X
hf : LocallyIntegrableOn f s μ
u : ℕ → Set X
su : s ⊆ ⋃ n, u n
hu : ∀ (n : ℕ), IntegrableOn f (u n ∩ s) μ
⊢ AEStronglyMeasurable f (μ.restrict s)
tactic: rcases hf.exists_nat_integrableOn with ⟨u, -, su, hu⟩
state_before: case intro.intro.intro
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
R : Type u_5
inst✝⁶ : MeasurableSpace X
inst✝⁵ : TopologicalSpace X
inst✝⁴ : MeasurableSpace Y
inst✝³ : TopologicalSpace Y
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedAddCommGroup F
f g : X → E
μ : Measure X
s : Set X
inst✝ : SecondCountableTopology X
hf : LocallyIntegrableOn f s μ
u : ℕ → Set X
su : s ⊆ ⋃ n, u n
hu : ∀ (n : ℕ), IntegrableOn f (u n ∩ s) μ
⊢ AEStronglyMeasurable f (μ.restrict s)
state_after: case intro.intro.intro
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
R : Type u_5
inst✝⁶ : MeasurableSpace X
inst✝⁵ : TopologicalSpace X
inst✝⁴ : MeasurableSpace Y
inst✝³ : TopologicalSpace Y
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedAddCommGroup F
f g : X → E
μ : Measure X
s : Set X
inst✝ : SecondCountableTopology X
hf : LocallyIntegrableOn f s μ
u : ℕ → Set X
su : s ⊆ ⋃ n, u n
hu : ∀ (n : ℕ), IntegrableOn f (u n ∩ s) μ
this : s = ⋃ n, u n ∩ s
⊢ AEStronglyMeasurable f (μ.restrict s)
tactic: have : s = ⋃ n, u n ∩ s := by rw [← iUnion_inter]; exact (inter_eq_right.mpr su).symm
state_before: case intro.intro.intro
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
R : Type u_5
inst✝⁶ : MeasurableSpace X
inst✝⁵ : TopologicalSpace X
inst✝⁴ : MeasurableSpace Y
inst✝³ : TopologicalSpace Y
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedAddCommGroup F
f g : X → E
μ : Measure X
s : Set X
inst✝ : SecondCountableTopology X
hf : LocallyIntegrableOn f s μ
u : ℕ → Set X
su : s ⊆ ⋃ n, u n
hu : ∀ (n : ℕ), IntegrableOn f (u n ∩ s) μ
this : s = ⋃ n, u n ∩ s
⊢ AEStronglyMeasurable f (μ.restrict s)
state_after: case intro.intro.intro
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
R : Type u_5
inst✝⁶ : MeasurableSpace X
inst✝⁵ : TopologicalSpace X
inst✝⁴ : MeasurableSpace Y
inst✝³ : TopologicalSpace Y
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedAddCommGroup F
f g : X → E
μ : Measure X
s : Set X
inst✝ : SecondCountableTopology X
hf : LocallyIntegrableOn f s μ
u : ℕ → Set X
su : s ⊆ ⋃ n, u n
hu : ∀ (n : ℕ), IntegrableOn f (u n ∩ s) μ
this : s = ⋃ n, u n ∩ s
⊢ ∀ (i : ℕ), AEStronglyMeasurable f (μ.restrict (u i ∩ s))
tactic: rw [this, aestronglyMeasurable_iUnion_iff]
state_before: case intro.intro.intro
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
R : Type u_5
inst✝⁶ : MeasurableSpace X
inst✝⁵ : TopologicalSpace X
inst✝⁴ : MeasurableSpace Y
inst✝³ : TopologicalSpace Y
inst✝² : NormedAddCommGroup E
inst✝¹ : NormedAddCommGroup F
f g : X → E
μ : Measure X
s : Set X
inst✝ : SecondCountableTopology X
hf : LocallyIntegrableOn f s μ
u : ℕ → Set X
su : s ⊆ ⋃ n, u n
hu : ∀ (n : ℕ), IntegrableOn f (u n ∩ s) μ
this : s = ⋃ n, u n ∩ s
⊢ ∀ (i : ℕ), AEStronglyMeasurable f (μ.restrict (u i ∩ s))
state_after: no goals
tactic: exact fun i : ℕ => (hu i).aestronglyMeasurable