Theorem: MeasureTheory.inducedOuterMeasure_caratheodory
File: Mathlib/MeasureTheory/OuterMeasure/Induced.lean

Proof steps:
state_before: α : Type u_1
P : Set α → Prop
m : (s : Set α) → P s → ℝ≥0∞
P0 : P ∅
m0 : m ∅ P0 = 0
PU : ∀ ⦃f : ℕ → Set α⦄, (∀ (i : ℕ), P (f i)) → P (⋃ i, f i)
mU : ∀ ⦃f : ℕ → Set α⦄ (hm : ∀ (i : ℕ), P (f i)), Pairwise (Disjoint on f) → m (⋃ i, f i) ⋯ = ∑' (i : ℕ), m (f i) ⋯
msU : ∀ ⦃f : ℕ → Set α⦄ (hm : ∀ (i : ℕ), P (f i)), m (⋃ i, f i) ⋯ ≤ ∑' (i : ℕ), m (f i) ⋯
m_mono : ∀ ⦃s₁ s₂ : Set α⦄ (hs₁ : P s₁) (hs₂ : P s₂), s₁ ⊆ s₂ → m s₁ hs₁ ≤ m s₂ hs₂
s : Set α
⊢ MeasurableSet s ↔
    ∀ (t : Set α),
      P t →
        (inducedOuterMeasure m P0 m0) (t ∩ s) + (inducedOuterMeasure m P0 m0) (t \ s) ≤ (inducedOuterMeasure m P0 m0) t
state_after: α : Type u_1
P : Set α → Prop
m : (s : Set α) → P s → ℝ≥0∞
P0 : P ∅
m0 : m ∅ P0 = 0
PU : ∀ ⦃f : ℕ → Set α⦄, (∀ (i : ℕ), P (f i)) → P (⋃ i, f i)
mU : ∀ ⦃f : ℕ → Set α⦄ (hm : ∀ (i : ℕ), P (f i)), Pairwise (Disjoint on f) → m (⋃ i, f i) ⋯ = ∑' (i : ℕ), m (f i) ⋯
msU : ∀ ⦃f : ℕ → Set α⦄ (hm : ∀ (i : ℕ), P (f i)), m (⋃ i, f i) ⋯ ≤ ∑' (i : ℕ), m (f i) ⋯
m_mono : ∀ ⦃s₁ s₂ : Set α⦄ (hs₁ : P s₁) (hs₂ : P s₂), s₁ ⊆ s₂ → m s₁ hs₁ ≤ m s₂ hs₂
s : Set α
⊢ (∀ (t : Set α),
      (inducedOuterMeasure m P0 m0) (t ∩ s) + (inducedOuterMeasure m P0 m0) (t \ s) ≤ (inducedOuterMeasure m P0 m0) t) ↔
    ∀ (t : Set α),
      P t →
        (inducedOuterMeasure m P0 m0) (t ∩ s) + (inducedOuterMeasure m P0 m0) (t \ s) ≤ (inducedOuterMeasure m P0 m0) t
tactic: rw [isCaratheodory_iff_le]
state_before: α : Type u_1
P : Set α → Prop
m : (s : Set α) → P s → ℝ≥0∞
P0 : P ∅
m0 : m ∅ P0 = 0
PU : ∀ ⦃f : ℕ → Set α⦄, (∀ (i : ℕ), P (f i)) → P (⋃ i, f i)
mU : ∀ ⦃f : ℕ → Set α⦄ (hm : ∀ (i : ℕ), P (f i)), Pairwise (Disjoint on f) → m (⋃ i, f i) ⋯ = ∑' (i : ℕ), m (f i) ⋯
msU : ∀ ⦃f : ℕ → Set α⦄ (hm : ∀ (i : ℕ), P (f i)), m (⋃ i, f i) ⋯ ≤ ∑' (i : ℕ), m (f i) ⋯
m_mono : ∀ ⦃s₁ s₂ : Set α⦄ (hs₁ : P s₁) (hs₂ : P s₂), s₁ ⊆ s₂ → m s₁ hs₁ ≤ m s₂ hs₂
s : Set α
⊢ (∀ (t : Set α),
      (inducedOuterMeasure m P0 m0) (t ∩ s) + (inducedOuterMeasure m P0 m0) (t \ s) ≤ (inducedOuterMeasure m P0 m0) t) ↔
    ∀ (t : Set α),
      P t →
        (inducedOuterMeasure m P0 m0) (t ∩ s) + (inducedOuterMeasure m P0 m0) (t \ s) ≤ (inducedOuterMeasure m P0 m0) t
state_after: case mp
α : Type u_1
P : Set α → Prop
m : (s : Set α) → P s → ℝ≥0∞
P0 : P ∅
m0 : m ∅ P0 = 0
PU : ∀ ⦃f : ℕ → Set α⦄, (∀ (i : ℕ), P (f i)) → P (⋃ i, f i)
mU : ∀ ⦃f : ℕ → Set α⦄ (hm : ∀ (i : ℕ), P (f i)), Pairwise (Disjoint on f) → m (⋃ i, f i) ⋯ = ∑' (i : ℕ), m (f i) ⋯
msU : ∀ ⦃f : ℕ → Set α⦄ (hm : ∀ (i : ℕ), P (f i)), m (⋃ i, f i) ⋯ ≤ ∑' (i : ℕ), m (f i) ⋯
m_mono : ∀ ⦃s₁ s₂ : Set α⦄ (hs₁ : P s₁) (hs₂ : P s₂), s₁ ⊆ s₂ → m s₁ hs₁ ≤ m s₂ hs₂
s : Set α
⊢ (∀ (t : Set α),
      (inducedOuterMeasure m P0 m0) (t ∩ s) + (inducedOuterMeasure m P0 m0) (t \ s) ≤ (inducedOuterMeasure m P0 m0) t) →
    ∀ (t : Set α),
      P t →
        (inducedOuterMeasure m P0 m0) (t ∩ s) + (inducedOuterMeasure m P0 m0) (t \ s) ≤ (inducedOuterMeasure m P0 m0) t

case mpr
α : Type u_1
P : Set α → Prop
m : (s : Set α) → P s → ℝ≥0∞
P0 : P ∅
m0 : m ∅ P0 = 0
PU : ∀ ⦃f : ℕ → Set α⦄, (∀ (i : ℕ), P (f i)) → P (⋃ i, f i)
mU : ∀ ⦃f : ℕ → Set α⦄ (hm : ∀ (i : ℕ), P (f i)), Pairwise (Disjoint on f) → m (⋃ i, f i) ⋯ = ∑' (i : ℕ), m (f i) ⋯
msU : ∀ ⦃f : ℕ → Set α⦄ (hm : ∀ (i : ℕ), P (f i)), m (⋃ i, f i) ⋯ ≤ ∑' (i : ℕ), m (f i) ⋯
m_mono : ∀ ⦃s₁ s₂ : Set α⦄ (hs₁ : P s₁) (hs₂ : P s₂), s₁ ⊆ s₂ → m s₁ hs₁ ≤ m s₂ hs₂
s : Set α
⊢ (∀ (t : Set α),
      P t →
        (inducedOuterMeasure m P0 m0) (t ∩ s) + (inducedOuterMeasure m P0 m0) (t \ s) ≤
          (inducedOuterMeasure m P0 m0) t) →
    ∀ (t : Set α),
      (inducedOuterMeasure m P0 m0) (t ∩ s) + (inducedOuterMeasure m P0 m0) (t \ s) ≤ (inducedOuterMeasure m P0 m0) t
tactic: constructor