Module: Mathlib.MeasureTheory.VectorMeasure.AddContent

Goal state before:
pp: case hm
α : Type u_1
hα : MeasurableSpace α
E : Type u_2
inst✝² : NormedAddCommGroup E
inst✝¹ : CompleteSpace E
μ : Measure α
inst✝ : IsFiniteMeasure μ
C : Set (Set α)
m : AddContent E C
hC : IsSetRing C
hCmeas : ∀ s ∈ C, MeasurableSet s
hm : ∀ s ∈ C, ‖m s‖ₑ ≤ μ s
h'C : ∀ (t : Set α) (ε : ℝ≥0∞), MeasurableSet t → 0 < ε → ∃ s ∈ C, μ (s ∆ t) < ε
C' : Set (MeasuredSets μ) := ⋯
C'C : ∀ s ∈ C', ↑s ∈ C
C'_dense : Dense C'
m₀ : ↑C' → E := ⋯
lip : LipschitzWith 1 m₀
m₁ : MeasuredSets μ → E := ⋯
m₁_lip : LipschitzWith 1 m₁
hBound : ∀ (s : MeasuredSets μ), ‖m₁ s‖ₑ ≤ μ ↑s
hAddit : ∀ (s t : MeasuredSets μ), Disjoint ↑s ↑t → m₁ ⟨↑s ∪ ↑t, ⋯⟩ = m₁ s + m₁ t
m' : Set α → E := ⋯
⊢ ∀ (s : Set α), ‖m' s‖ₑ ≤ μ s

pp: case h'm
α : Type u_1
hα : MeasurableSpace α
E : Type u_2
inst✝² : NormedAddCommGroup E
inst✝¹ : CompleteSpace E
μ : Measure α
inst✝ : IsFiniteMeasure μ
C : Set (Set α)
m : AddContent E C
hC : IsSetRing C
hCmeas : ∀ s ∈ C, MeasurableSet s
hm : ∀ s ∈ C, ‖m s‖ₑ ≤ μ s
h'C : ∀ (t : Set α) (ε : ℝ≥0∞), MeasurableSet t → 0 < ε → ∃ s ∈ C, μ (s ∆ t) < ε
C' : Set (MeasuredSets μ) := ⋯
C'C : ∀ s ∈ C', ↑s ∈ C
C'_dense : Dense C'
m₀ : ↑C' → E := ⋯
lip : LipschitzWith 1 m₀
m₁ : MeasuredSets μ → E := ⋯
m₁_lip : LipschitzWith 1 m₁
hBound : ∀ (s : MeasuredSets μ), ‖m₁ s‖ₑ ≤ μ ↑s
hAddit : ∀ (s t : MeasuredSets μ), Disjoint ↑s ↑t → m₁ ⟨↑s ∪ ↑t, ⋯⟩ = m₁ s + m₁ t
m' : Set α → E := ⋯
⊢ ∀ (s t : Set α), MeasurableSet s → MeasurableSet t → Disjoint s t → m' (s ∪ t) = m' s + m' t

pp: case h''m
α : Type u_1
hα : MeasurableSpace α
E : Type u_2
inst✝² : NormedAddCommGroup E
inst✝¹ : CompleteSpace E
μ : Measure α
inst✝ : IsFiniteMeasure μ
C : Set (Set α)
m : AddContent E C
hC : IsSetRing C
hCmeas : ∀ s ∈ C, MeasurableSet s
hm : ∀ s ∈ C, ‖m s‖ₑ ≤ μ s
h'C : ∀ (t : Set α) (ε : ℝ≥0∞), MeasurableSet t → 0 < ε → ∃ s ∈ C, μ (s ∆ t) < ε
C' : Set (MeasuredSets μ) := ⋯
C'C : ∀ s ∈ C', ↑s ∈ C
C'_dense : Dense C'
m₀ : ↑C' → E := ⋯
lip : LipschitzWith 1 m₀
m₁ : MeasuredSets μ → E := ⋯
m₁_lip : LipschitzWith 1 m₁
hBound : ∀ (s : MeasuredSets μ), ‖m₁ s‖ₑ ≤ μ ↑s
hAddit : ∀ (s t : MeasuredSets μ), Disjoint ↑s ↑t → m₁ ⟨↑s ∪ ↑t, ⋯⟩ = m₁ s + m₁ t
m' : Set α → E := ⋯
⊢ ∀ (s : Set α), ¬MeasurableSet s → m' s = 0

Tactic:
· intro s
      by_cases hs : MeasurableSet s
      · simpa [hs, m'] using! hBound _
      · simp [hs, m']

Goal state after:
case h'm
α : Type u_1
hα : MeasurableSpace α
E : Type u_2
inst✝² : NormedAddCommGroup E
inst✝¹ : CompleteSpace E
μ : Measure α
inst✝ : IsFiniteMeasure μ
C : Set (Set α)
m : AddContent E C
hC : IsSetRing C
hCmeas : ∀ s ∈ C, MeasurableSet s
hm : ∀ s ∈ C, ‖m s‖ₑ ≤ μ s
h'C : ∀ (t : Set α) (ε : ℝ≥0∞), MeasurableSet t → 0 < ε → ∃ s ∈ C, μ (s ∆ t) < ε
C' : Set (MeasuredSets μ) := ⋯
C'C : ∀ s ∈ C', ↑s ∈ C
C'_dense : Dense C'
m₀ : ↑C' → E := ⋯
lip : LipschitzWith 1 m₀
m₁ : MeasuredSets μ → E := ⋯
m₁_lip : LipschitzWith 1 m₁
hBound : ∀ (s : MeasuredSets μ), ‖m₁ s‖ₑ ≤ μ ↑s
hAddit : ∀ (s t : MeasuredSets μ), Disjoint ↑s ↑t → m₁ ⟨↑s ∪ ↑t, ⋯⟩ = m₁ s + m₁ t
m' : Set α → E := ⋯
⊢ ∀ (s t : Set α), MeasurableSet s → MeasurableSet t → Disjoint s t → m' (s ∪ t) = m' s + m' t

case h''m
α : Type u_1
hα : MeasurableSpace α
E : Type u_2
inst✝² : NormedAddCommGroup E
inst✝¹ : CompleteSpace E
μ : Measure α
inst✝ : IsFiniteMeasure μ
C : Set (Set α)
m : AddContent E C
hC : IsSetRing C
hCmeas : ∀ s ∈ C, MeasurableSet s
hm : ∀ s ∈ C, ‖m s‖ₑ ≤ μ s
h'C : ∀ (t : Set α) (ε : ℝ≥0∞), MeasurableSet t → 0 < ε → ∃ s ∈ C, μ (s ∆ t) < ε
C' : Set (MeasuredSets μ) := ⋯
C'C : ∀ s ∈ C', ↑s ∈ C
C'_dense : Dense C'
m₀ : ↑C' → E := ⋯
lip : LipschitzWith 1 m₀
m₁ : MeasuredSets μ → E := ⋯
m₁_lip : LipschitzWith 1 m₁
hBound : ∀ (s : MeasuredSets μ), ‖m₁ s‖ₑ ≤ μ ↑s
hAddit : ∀ (s t : MeasuredSets μ), Disjoint ↑s ↑t → m₁ ⟨↑s ∪ ↑t, ⋯⟩ = m₁ s + m₁ t
m' : Set α → E := ⋯
⊢ ∀ (s : Set α), ¬MeasurableSet s → m' s = 0