Module: Mathlib.MeasureTheory.Function.ContinuousMapDense

Goal state before:
pp: α : Type u_1
inst✝⁸ : TopologicalSpace α
inst✝⁷ : NormalSpace α
inst✝⁶ : MeasurableSpace α
inst✝⁵ : BorelSpace α
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
μ : Measure α
p : ℝ≥0∞
inst✝³ : NormedSpace ℝ E
inst✝² : R1Space α
inst✝¹ : WeaklyLocallyCompactSpace α
inst✝ : μ.Regular
hp : p ≠ ∞
f✝ : α → E
hf : MemLp f✝ p μ
ε✝ : ℝ≥0∞
hε✝ : ε✝ ≠ 0
c : E
t : Set α
ht : MeasurableSet t
htμ : μ t < ∞
ε : ℝ≥0∞
hε : ε ≠ 0
δ : ℝ≥0∞
δpos : 0 < δ
hδ :
  ∀ (f g : α → E),
    AEStronglyMeasurable f μ →
      AEStronglyMeasurable g μ → eLpNorm f p μ ≤ δ → eLpNorm g p μ ≤ δ → eLpNorm (f + g) p μ < ε
η : ℝ≥0
ηpos : 0 < η
hη : ∀ (s : Set α), μ s ≤ ↑η → eLpNorm (s.indicator fun _x ↦ c) p μ ≤ δ
hη_pos' : 0 < ↑η
s : Set α
st : s ⊆ t
s_compact : IsCompact s
s_closed : IsClosed[inst✝⁸] s
μs : μ (t \ s) < ↑η
hsμ : μ s < ∞
I1 : eLpNorm ((s.indicator fun _y ↦ c) - t.indicator fun _y ↦ c) p μ ≤ δ
k : Set α
k_compact : IsCompact k
sk : s ⊆ interior k
f : α → E
f_cont : Continuous[inst✝⁸, PseudoMetricSpace.toUniformSpace.toTopologicalSpace] f
I2 : eLpNorm (fun x ↦ f x - s.indicator (fun _y ↦ c) x) p μ ≤ δ
_f_bound : ∀ (x : α), ‖f x‖ ≤ ‖c‖
f_support : Function.support f ⊆ interior k
f_mem : MemLp f p μ
⊢ ∃ g,
    eLpNorm (g - t.indicator fun x ↦ c) p μ ≤ ε ∧
      Continuous[inst✝⁸, PseudoMetricSpace.toUniformSpace.toTopologicalSpace] g ∧ MemLp g p μ ∧ HasCompactSupport g

Tactic:
have I3 : eLpNorm (f - t.indicator fun _y => c) p μ ≤ ε := by
    convert!
      (hδ _ _
          (f_mem.aestronglyMeasurable.sub
            (aestronglyMeasurable_const.indicator s_closed.measurableSet))
          ((aestronglyMeasurable_const.indicator s_closed.measurableSet).sub
            (aestronglyMeasurable_const.indicator ht))
          I2 I1).le using 2
    simp only [sub_add_sub_cancel]

Goal state after:
α : Type u_1
inst✝⁸ : TopologicalSpace α
inst✝⁷ : NormalSpace α
inst✝⁶ : MeasurableSpace α
inst✝⁵ : BorelSpace α
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
μ : Measure α
p : ℝ≥0∞
inst✝³ : NormedSpace ℝ E
inst✝² : R1Space α
inst✝¹ : WeaklyLocallyCompactSpace α
inst✝ : μ.Regular
hp : p ≠ ∞
f✝ : α → E
hf : MemLp f✝ p μ
ε✝ : ℝ≥0∞
hε✝ : ε✝ ≠ 0
c : E
t : Set α
ht : MeasurableSet t
htμ : μ t < ∞
ε : ℝ≥0∞
hε : ε ≠ 0
δ : ℝ≥0∞
δpos : 0 < δ
hδ :
  ∀ (f g : α → E),
    AEStronglyMeasurable f μ →
      AEStronglyMeasurable g μ → eLpNorm f p μ ≤ δ → eLpNorm g p μ ≤ δ → eLpNorm (f + g) p μ < ε
η : ℝ≥0
ηpos : 0 < η
hη : ∀ (s : Set α), μ s ≤ ↑η → eLpNorm (s.indicator fun _x ↦ c) p μ ≤ δ
hη_pos' : 0 < ↑η
s : Set α
st : s ⊆ t
s_compact : IsCompact s
s_closed : IsClosed[inst✝⁸] s
μs : μ (t \ s) < ↑η
hsμ : μ s < ∞
I1 : eLpNorm ((s.indicator fun _y ↦ c) - t.indicator fun _y ↦ c) p μ ≤ δ
k : Set α
k_compact : IsCompact k
sk : s ⊆ interior k
f : α → E
f_cont : Continuous[inst✝⁸, PseudoMetricSpace.toUniformSpace.toTopologicalSpace] f
I2 : eLpNorm (fun x ↦ f x - s.indicator (fun _y ↦ c) x) p μ ≤ δ
_f_bound : ∀ (x : α), ‖f x‖ ≤ ‖c‖
f_support : Function.support f ⊆ interior k
f_mem : MemLp f p μ
I3 : eLpNorm (f - t.indicator fun _y ↦ c) p μ ≤ ε
⊢ ∃ g,
    eLpNorm (g - t.indicator fun x ↦ c) p μ ≤ ε ∧
      Continuous[inst✝⁸, PseudoMetricSpace.toUniformSpace.toTopologicalSpace] g ∧ MemLp g p μ ∧ HasCompactSupport g