Module: Mathlib.Analysis.Distribution.AEEqOfIntegralContDiff

Goal state before:
pp: E : Type u_1
inst✝¹³ : NormedAddCommGroup E
inst✝¹² : NormedSpace ℝ E
inst✝¹¹ : FiniteDimensional ℝ E
F : Type u_2
inst✝¹⁰ : NormedAddCommGroup F
inst✝⁹ : NormedSpace ℝ F
inst✝⁸ : CompleteSpace F
H : Type u_3
inst✝⁷ : TopologicalSpace H
I : ModelWithCorners ℝ E H
M : Type u_4
inst✝⁶ : TopologicalSpace M
inst✝⁵ : ChartedSpace H M
inst✝⁴ : IsManifold I ∞ M
inst✝³ : MeasurableSpace M
inst✝² : BorelSpace M
inst✝¹ : T2Space M
f : M → F
μ : Measure M
inst✝ : SigmaCompactSpace M
hf : LocallyIntegrable f μ
h : ∀ (g : M → ℝ), ContMDiff I 𝓘(ℝ, ℝ) ∞ g → HasCompactSupport g → ∫ (x : M), g x • f x ∂μ = 0
this✝² : LocallyCompactSpace H
this✝¹ : LocallyCompactSpace M
this✝ : SecondCountableTopology H
this : SecondCountableTopology M
x✝ : MetricSpace M := metrizableSpaceMetric M
s : Set M
hs : IsCompact s
δ : ℝ
δpos : 0 < δ
hδ : IsCompact (cthickening δ s)
u : ℕ → ℝ
u_pos : ∀ (n : ℕ), u n ∈ Ioo 0 δ
u_lim : Tendsto u atTop (𝓝 0)
v : ℕ → Set M := fun n ↦ thickening (u n) s
K : Set M
K_compact : IsCompact K
vK : ∀ (n : ℕ), v n ⊆ K
g : ℕ → M → ℝ
g_supp : ∀ (n : ℕ), support (g n) = v n
g_diff : ∀ (n : ℕ), ContMDiff I 𝓘(ℝ, ℝ) ∞ (g n)
g_range : ∀ (n : ℕ), range (g n) ⊆ Icc 0 1
hg : ∀ (n : ℕ), ∀ x ∈ s, g n x = 1
bound : M → ℝ := K.indicator fun x ↦ ‖f x‖
A : ∀ (n : ℕ), AEStronglyMeasurable (fun x ↦ g n x • f x) μ
B : Integrable bound μ
⊢ Tendsto (fun n ↦ ∫ (x : M), g n x • f x ∂μ) atTop (𝓝 (∫ (x : M), s.indicator f x ∂μ))

Tactic:
have C : ∀ n, ∀ᵐ x ∂μ, ‖g n x • f x‖ ≤ bound x := by
      intro n
      filter_upwards with x
      rw [norm_smul]
      refine le_indicator_apply (fun _ ↦ ?_) (fun hxK ↦ ?_)
      · have : ‖g n x‖ ≤ 1 := by
          have := g_range n (mem_range_self (f := g n) x)
          rw [Real.norm_of_nonneg this.1]
          exact this.2
        exact mul_le_of_le_one_left (norm_nonneg _) this
      · have : g n x = 0 := by rw [← notMem_support, g_supp]; contrapose hxK; exact vK n hxK
        simp [this]

Goal state after:
E : Type u_1
inst✝¹³ : NormedAddCommGroup E
inst✝¹² : NormedSpace ℝ E
inst✝¹¹ : FiniteDimensional ℝ E
F : Type u_2
inst✝¹⁰ : NormedAddCommGroup F
inst✝⁹ : NormedSpace ℝ F
inst✝⁸ : CompleteSpace F
H : Type u_3
inst✝⁷ : TopologicalSpace H
I : ModelWithCorners ℝ E H
M : Type u_4
inst✝⁶ : TopologicalSpace M
inst✝⁵ : ChartedSpace H M
inst✝⁴ : IsManifold I ∞ M
inst✝³ : MeasurableSpace M
inst✝² : BorelSpace M
inst✝¹ : T2Space M
f : M → F
μ : Measure M
inst✝ : SigmaCompactSpace M
hf : LocallyIntegrable f μ
h : ∀ (g : M → ℝ), ContMDiff I 𝓘(ℝ, ℝ) ∞ g → HasCompactSupport g → ∫ (x : M), g x • f x ∂μ = 0
this✝² : LocallyCompactSpace H
this✝¹ : LocallyCompactSpace M
this✝ : SecondCountableTopology H
this : SecondCountableTopology M
x✝ : MetricSpace M := metrizableSpaceMetric M
s : Set M
hs : IsCompact s
δ : ℝ
δpos : 0 < δ
hδ : IsCompact (cthickening δ s)
u : ℕ → ℝ
u_pos : ∀ (n : ℕ), u n ∈ Ioo 0 δ
u_lim : Tendsto u atTop (𝓝 0)
v : ℕ → Set M := fun n ↦ thickening (u n) s
K : Set M
K_compact : IsCompact K
vK : ∀ (n : ℕ), v n ⊆ K
g : ℕ → M → ℝ
g_supp : ∀ (n : ℕ), support (g n) = v n
g_diff : ∀ (n : ℕ), ContMDiff I 𝓘(ℝ, ℝ) ∞ (g n)
g_range : ∀ (n : ℕ), range (g n) ⊆ Icc 0 1
hg : ∀ (n : ℕ), ∀ x ∈ s, g n x = 1
bound : M → ℝ := K.indicator fun x ↦ ‖f x‖
A : ∀ (n : ℕ), AEStronglyMeasurable (fun x ↦ g n x • f x) μ
B : Integrable bound μ
C : ∀ (n : ℕ), ∀ᵐ (x : M) ∂μ, ‖g n x • f x‖ ≤ bound x
⊢ Tendsto (fun n ↦ ∫ (x : M), g n x • f x ∂μ) atTop (𝓝 (∫ (x : M), s.indicator f x ∂μ))