Theorem: MeasureTheory.UnifTight.add
File: Mathlib/MeasureTheory/Function/UnifTight.lean

Proof steps:
state_before: α : Type u_1
β : Type u_2
ι : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝ : NormedAddCommGroup β
f g : ι → α → β
p : ℝ≥0∞
hf : UnifTight f p μ
hg : UnifTight g p μ
hf_meas : ∀ (i : ι), AEStronglyMeasurable (f i) μ
hg_meas : ∀ (i : ι), AEStronglyMeasurable (g i) μ
ε : ℝ≥0
hε : 0 < ε
⊢ ∃ s, μ s ≠ ⊤ ∧ ∀ (i : ι), eLpNorm (sᶜ.indicator ((f + g) i)) p μ ≤ ↑ε
state_after: case intro.intro
α : Type u_1
β : Type u_2
ι : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝ : NormedAddCommGroup β
f g : ι → α → β
p : ℝ≥0∞
hf : UnifTight f p μ
hg : UnifTight g p μ
hf_meas : ∀ (i : ι), AEStronglyMeasurable (f i) μ
hg_meas : ∀ (i : ι), AEStronglyMeasurable (g i) μ
ε : ℝ≥0
hε : 0 < ε
η : ℝ≥0∞
hη_pos : 0 < η
hη :
  ∀ (f g : α → β),
    AEStronglyMeasurable f μ →
      AEStronglyMeasurable g μ → eLpNorm f p μ ≤ η → eLpNorm g p μ ≤ η → eLpNorm (f + g) p μ < ↑ε
⊢ ∃ s, μ s ≠ ⊤ ∧ ∀ (i : ι), eLpNorm (sᶜ.indicator ((f + g) i)) p μ ≤ ↑ε
tactic: rcases exists_Lp_half β μ p (coe_ne_zero.mpr hε.ne') with ⟨η, hη_pos, hη⟩
state_before: case intro.intro
α : Type u_1
β : Type u_2
ι : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝ : NormedAddCommGroup β
f g : ι → α → β
p : ℝ≥0∞
hf : UnifTight f p μ
hg : UnifTight g p μ
hf_meas : ∀ (i : ι), AEStronglyMeasurable (f i) μ
hg_meas : ∀ (i : ι), AEStronglyMeasurable (g i) μ
ε : ℝ≥0
hε : 0 < ε
η : ℝ≥0∞
hη_pos : 0 < η
hη :
  ∀ (f g : α → β),
    AEStronglyMeasurable f μ →
      AEStronglyMeasurable g μ → eLpNorm f p μ ≤ η → eLpNorm g p μ ≤ η → eLpNorm (f + g) p μ < ↑ε
⊢ ∃ s, μ s ≠ ⊤ ∧ ∀ (i : ι), eLpNorm (sᶜ.indicator ((f + g) i)) p μ ≤ ↑ε
state_after: case pos
α : Type u_1
β : Type u_2
ι : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝ : NormedAddCommGroup β
f g : ι → α → β
p : ℝ≥0∞
hf : UnifTight f p μ
hg : UnifTight g p μ
hf_meas : ∀ (i : ι), AEStronglyMeasurable (f i) μ
hg_meas : ∀ (i : ι), AEStronglyMeasurable (g i) μ
ε : ℝ≥0
hε : 0 < ε
η : ℝ≥0∞
hη_pos : 0 < η
hη :
  ∀ (f g : α → β),
    AEStronglyMeasurable f μ →
      AEStronglyMeasurable g μ → eLpNorm f p μ ≤ η → eLpNorm g p μ ≤ η → eLpNorm (f + g) p μ < ↑ε
hη_top : η = ⊤
⊢ ∃ s, μ s ≠ ⊤ ∧ ∀ (i : ι), eLpNorm (sᶜ.indicator ((f + g) i)) p μ ≤ ↑ε

case neg
α : Type u_1
β : Type u_2
ι : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝ : NormedAddCommGroup β
f g : ι → α → β
p : ℝ≥0∞
hf : UnifTight f p μ
hg : UnifTight g p μ
hf_meas : ∀ (i : ι), AEStronglyMeasurable (f i) μ
hg_meas : ∀ (i : ι), AEStronglyMeasurable (g i) μ
ε : ℝ≥0
hε : 0 < ε
η : ℝ≥0∞
hη_pos : 0 < η
hη :
  ∀ (f g : α → β),
    AEStronglyMeasurable f μ →
      AEStronglyMeasurable g μ → eLpNorm f p μ ≤ η → eLpNorm g p μ ≤ η → eLpNorm (f + g) p μ < ↑ε
hη_top : ¬η = ⊤
⊢ ∃ s, μ s ≠ ⊤ ∧ ∀ (i : ι), eLpNorm (sᶜ.indicator ((f + g) i)) p μ ≤ ↑ε
tactic: by_cases hη_top : η = ∞
state_before: case neg
α : Type u_1
β : Type u_2
ι : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝ : NormedAddCommGroup β
f g : ι → α → β
p : ℝ≥0∞
hf : UnifTight f p μ
hg : UnifTight g p μ
hf_meas : ∀ (i : ι), AEStronglyMeasurable (f i) μ
hg_meas : ∀ (i : ι), AEStronglyMeasurable (g i) μ
ε : ℝ≥0
hε : 0 < ε
η : ℝ≥0∞
hη_pos : 0 < η
hη :
  ∀ (f g : α → β),
    AEStronglyMeasurable f μ →
      AEStronglyMeasurable g μ → eLpNorm f p μ ≤ η → eLpNorm g p μ ≤ η → eLpNorm (f + g) p μ < ↑ε
hη_top : ¬η = ⊤
⊢ ∃ s, μ s ≠ ⊤ ∧ ∀ (i : ι), eLpNorm (sᶜ.indicator ((f + g) i)) p μ ≤ ↑ε
state_after: case neg.intro.intro.intro.intro
α : Type u_1
β : Type u_2
ι : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝ : NormedAddCommGroup β
f g : ι → α → β
p : ℝ≥0∞
hf : UnifTight f p μ
hg : UnifTight g p μ
hf_meas : ∀ (i : ι), AEStronglyMeasurable (f i) μ
hg_meas : ∀ (i : ι), AEStronglyMeasurable (g i) μ
ε : ℝ≥0
hε : 0 < ε
η : ℝ≥0∞
hη_pos : 0 < η
hη :
  ∀ (f g : α → β),
    AEStronglyMeasurable f μ →
      AEStronglyMeasurable g μ → eLpNorm f p μ ≤ η → eLpNorm g p μ ≤ η → eLpNorm (f + g) p μ < ↑ε
hη_top : ¬η = ⊤
s : Set α
hμs : s ∈ μ.cofinite
hsm : MeasurableSet s
hfs : ∀ (i : ι), eLpNorm (s.indicator (f i)) p μ ≤ η
hgs : ∀ (i : ι), eLpNorm (s.indicator (g i)) p μ ≤ η
⊢ ∃ s, μ s ≠ ⊤ ∧ ∀ (i : ι), eLpNorm (sᶜ.indicator ((f + g) i)) p μ ≤ ↑ε
tactic: obtain ⟨s, hμs, hsm, hfs, hgs⟩ :
      ∃ s ∈ μ.cofinite, MeasurableSet s ∧
        (∀ i, eLpNorm (s.indicator (f i)) p μ ≤ η) ∧
        (∀ i, eLpNorm (s.indicator (g i)) p μ ≤ η) :=
    ((hf.eventually_cofinite_indicator hη_pos.ne').and
      (hg.eventually_cofinite_indicator hη_pos.ne')).exists_measurable_mem_of_smallSets
state_before: case neg.intro.intro.intro.intro
α : Type u_1
β : Type u_2
ι : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝ : NormedAddCommGroup β
f g : ι → α → β
p : ℝ≥0∞
hf : UnifTight f p μ
hg : UnifTight g p μ
hf_meas : ∀ (i : ι), AEStronglyMeasurable (f i) μ
hg_meas : ∀ (i : ι), AEStronglyMeasurable (g i) μ
ε : ℝ≥0
hε : 0 < ε
η : ℝ≥0∞
hη_pos : 0 < η
hη :
  ∀ (f g : α → β),
    AEStronglyMeasurable f μ →
      AEStronglyMeasurable g μ → eLpNorm f p μ ≤ η → eLpNorm g p μ ≤ η → eLpNorm (f + g) p μ < ↑ε
hη_top : ¬η = ⊤
s : Set α
hμs : s ∈ μ.cofinite
hsm : MeasurableSet s
hfs : ∀ (i : ι), eLpNorm (s.indicator (f i)) p μ ≤ η
hgs : ∀ (i : ι), eLpNorm (s.indicator (g i)) p μ ≤ η
⊢ ∃ s, μ s ≠ ⊤ ∧ ∀ (i : ι), eLpNorm (sᶜ.indicator ((f + g) i)) p μ ≤ ↑ε
state_after: case neg.intro.intro.intro.intro
α : Type u_1
β : Type u_2
ι : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝ : NormedAddCommGroup β
f g : ι → α → β
p : ℝ≥0∞
hf : UnifTight f p μ
hg : UnifTight g p μ
hf_meas : ∀ (i : ι), AEStronglyMeasurable (f i) μ
hg_meas : ∀ (i : ι), AEStronglyMeasurable (g i) μ
ε : ℝ≥0
hε : 0 < ε
η : ℝ≥0∞
hη_pos : 0 < η
hη :
  ∀ (f g : α → β),
    AEStronglyMeasurable f μ →
      AEStronglyMeasurable g μ → eLpNorm f p μ ≤ η → eLpNorm g p μ ≤ η → eLpNorm (f + g) p μ < ↑ε
hη_top : ¬η = ⊤
s : Set α
hμs : s ∈ μ.cofinite
hsm : MeasurableSet s
hfs : ∀ (i : ι), eLpNorm (s.indicator (f i)) p μ ≤ η
hgs : ∀ (i : ι), eLpNorm (s.indicator (g i)) p μ ≤ η
i : ι
⊢ eLpNorm (sᶜᶜ.indicator ((f + g) i)) p μ ≤ ↑ε
tactic: refine ⟨sᶜ, ne_of_lt hμs, fun i ↦ ?_⟩
state_before: case neg.intro.intro.intro.intro
α : Type u_1
β : Type u_2
ι : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝ : NormedAddCommGroup β
f g : ι → α → β
p : ℝ≥0∞
hf : UnifTight f p μ
hg : UnifTight g p μ
hf_meas : ∀ (i : ι), AEStronglyMeasurable (f i) μ
hg_meas : ∀ (i : ι), AEStronglyMeasurable (g i) μ
ε : ℝ≥0
hε : 0 < ε
η : ℝ≥0∞
hη_pos : 0 < η
hη :
  ∀ (f g : α → β),
    AEStronglyMeasurable f μ →
      AEStronglyMeasurable g μ → eLpNorm f p μ ≤ η → eLpNorm g p μ ≤ η → eLpNorm (f + g) p μ < ↑ε
hη_top : ¬η = ⊤
s : Set α
hμs : s ∈ μ.cofinite
hsm : MeasurableSet s
hfs : ∀ (i : ι), eLpNorm (s.indicator (f i)) p μ ≤ η
hgs : ∀ (i : ι), eLpNorm (s.indicator (g i)) p μ ≤ η
i : ι
⊢ eLpNorm (sᶜᶜ.indicator ((f + g) i)) p μ ≤ ↑ε
state_after: case neg.intro.intro.intro.intro
α : Type u_1
β : Type u_2
ι : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝ : NormedAddCommGroup β
f g : ι → α → β
p : ℝ≥0∞
hf : UnifTight f p μ
hg : UnifTight g p μ
hf_meas : ∀ (i : ι), AEStronglyMeasurable (f i) μ
hg_meas : ∀ (i : ι), AEStronglyMeasurable (g i) μ
ε : ℝ≥0
hε : 0 < ε
η : ℝ≥0∞
hη_pos : 0 < η
hη :
  ∀ (f g : α → β),
    AEStronglyMeasurable f μ →
      AEStronglyMeasurable g μ → eLpNorm f p μ ≤ η → eLpNorm g p μ ≤ η → eLpNorm (f + g) p μ < ↑ε
hη_top : ¬η = ⊤
s : Set α
hμs : s ∈ μ.cofinite
hsm : MeasurableSet s
hfs : ∀ (i : ι), eLpNorm (s.indicator (f i)) p μ ≤ η
hgs : ∀ (i : ι), eLpNorm (s.indicator (g i)) p μ ≤ η
i : ι
η_cast : ↑η.toNNReal = η
⊢ eLpNorm (sᶜᶜ.indicator ((f + g) i)) p μ ≤ ↑ε
tactic: have η_cast : ↑η.toNNReal = η := coe_toNNReal hη_top
state_before: case neg.intro.intro.intro.intro
α : Type u_1
β : Type u_2
ι : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝ : NormedAddCommGroup β
f g : ι → α → β
p : ℝ≥0∞
hf : UnifTight f p μ
hg : UnifTight g p μ
hf_meas : ∀ (i : ι), AEStronglyMeasurable (f i) μ
hg_meas : ∀ (i : ι), AEStronglyMeasurable (g i) μ
ε : ℝ≥0
hε : 0 < ε
η : ℝ≥0∞
hη_pos : 0 < η
hη :
  ∀ (f g : α → β),
    AEStronglyMeasurable f μ →
      AEStronglyMeasurable g μ → eLpNorm f p μ ≤ η → eLpNorm g p μ ≤ η → eLpNorm (f + g) p μ < ↑ε
hη_top : ¬η = ⊤
s : Set α
hμs : s ∈ μ.cofinite
hsm : MeasurableSet s
hfs : ∀ (i : ι), eLpNorm (s.indicator (f i)) p μ ≤ η
hgs : ∀ (i : ι), eLpNorm (s.indicator (g i)) p μ ≤ η
i : ι
η_cast : ↑η.toNNReal = η
⊢ eLpNorm (sᶜᶜ.indicator ((f + g) i)) p μ ≤ ↑ε
state_after: no goals
tactic: calc
    eLpNorm (indicator sᶜᶜ (f i + g i)) p μ
      = eLpNorm (indicator s (f i) + indicator s (g i)) p μ := by rw [compl_compl, indicator_add']
    _ ≤ ε := le_of_lt <|
      hη _ _ ((hf_meas i).indicator hsm) ((hg_meas i).indicator hsm)
        (η_cast ▸ hfs i) (η_cast ▸ hgs i)