-- Mathlib/MeasureTheory/Decomposition/Jordan.lean
theorem toSignedMeasure_injective : Injective <| @JordanDecomposition.toSignedMeasure α _

Proof state:
case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
α : Type u_1
inst✝ : MeasurableSpace α
j₁ j₂ : JordanDecomposition α
hj : j₁.toSignedMeasure = j₂.toSignedMeasure
S : Set α
hS₁ : MeasurableSet S
hS₂ : j₁.toSignedMeasure ≤[S] 0
hS₃ : 0 ≤[Sᶜ] j₁.toSignedMeasure
hS₄ : j₁.posPart S = 0
hS₅ : j₁.negPart Sᶜ = 0
T : Set α
hT₁ : MeasurableSet T
hT₂ : j₁.toSignedMeasure ≤[T] 0
hT₃ : 0 ≤[Tᶜ] j₁.toSignedMeasure
hT₄ : j₂.posPart T = 0
hT₅ : j₂.negPart Tᶜ = 0
⊢ j₁ = j₂

Tactic:
obtain ⟨hST₁, -⟩ :=
  of_symmDiff_compl_positive_negative hS₁.compl hT₁.compl ⟨hS₃, (compl_compl S).symm ▸ hS₂⟩
    ⟨hT₃, (compl_compl T).symm ▸ hT₂⟩

Result:
case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
α : Type u_1
inst✝ : MeasurableSpace α
j₁ j₂ : JordanDecomposition α
hj : j₁.toSignedMeasure = j₂.toSignedMeasure
S : Set α
hS₁ : MeasurableSet S
hS₂ : j₁.toSignedMeasure ≤[S] 0
hS₃ : 0 ≤[Sᶜ] j₁.toSignedMeasure
hS₄ : j₁.posPart S = 0
hS₅ : j₁.negPart Sᶜ = 0
T : Set α
hT₁ : MeasurableSet T
hT₂ : j₁.toSignedMeasure ≤[T] 0
hT₃ : 0 ≤[Tᶜ] j₁.toSignedMeasure
hT₄ : j₂.posPart T = 0
hT₅ : j₂.negPart Tᶜ = 0
hST₁ : ↑j₁.toSignedMeasure (symmDiff Sᶜ Tᶜ) = 0
⊢ j₁ = j₂

Proof state:
case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
α : Type u_1
inst✝ : MeasurableSpace α
j₁ j₂ : JordanDecomposition α
hj : j₁.toSignedMeasure = j₂.toSignedMeasure
S : Set α
hS₁ : MeasurableSet S
hS₂ : j₁.toSignedMeasure ≤[S] 0
hS₃ : 0 ≤[Sᶜ] j₁.toSignedMeasure
hS₄ : j₁.posPart S = 0
hS₅ : j₁.negPart Sᶜ = 0
T : Set α
hT₁ : MeasurableSet T
hT₂ : j₂.toSignedMeasure ≤[T] 0
hT₃ : 0 ≤[Tᶜ] j₂.toSignedMeasure
hT₄ : j₂.posPart T = 0
hT₅ : j₂.negPart Tᶜ = 0
⊢ j₁ = j₂

Tactic:
rw [← hj] at hT₂ hT₃

Result:
case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
α : Type u_1
inst✝ : MeasurableSpace α
j₁ j₂ : JordanDecomposition α
hj : j₁.toSignedMeasure = j₂.toSignedMeasure
S : Set α
hS₁ : MeasurableSet S
hS₂ : j₁.toSignedMeasure ≤[S] 0
hS₃ : 0 ≤[Sᶜ] j₁.toSignedMeasure
hS₄ : j₁.posPart S = 0
hS₅ : j₁.negPart Sᶜ = 0
T : Set α
hT₁ : MeasurableSet T
hT₂ : j₁.toSignedMeasure ≤[T] 0
hT₃ : 0 ≤[Tᶜ] j₁.toSignedMeasure
hT₄ : j₂.posPart T = 0
hT₅ : j₂.negPart Tᶜ = 0
⊢ j₁ = j₂

Proof state:
case hd
α : Type u_1
inst✝ : MeasurableSpace α
j₁ j₂ : JordanDecomposition α
hj : j₁.toSignedMeasure = j₂.toSignedMeasure
S : Set α
hS₁ : MeasurableSet S
hS₂ : j₁.toSignedMeasure ≤[S] 0
hS₃ : 0 ≤[Sᶜ] j₁.toSignedMeasure
hS₄ : j₁.posPart S = 0
hS₅ : j₁.negPart Sᶜ = 0
T : Set α
hT₁ : MeasurableSet T
hT₂ : j₁.toSignedMeasure ≤[T] 0
hT₃ : 0 ≤[Tᶜ] j₁.toSignedMeasure
hT₄ : j₂.posPart T = 0
hT₅ : j₂.negPart Tᶜ = 0
hST₁ : ↑j₁.toSignedMeasure (symmDiff Sᶜ Tᶜ) = 0
i : Set α
hi : MeasurableSet i
hμ₁ : (j₁.posPart i).toReal = ↑j₁.toSignedMeasure (i ∩ Sᶜ)
⊢ Disjoint (i ∩ T) (i ∩ Tᶜ)

Tactic:
exact
  Set.disjoint_of_subset_left Set.inter_subset_right
    (Set.disjoint_of_subset_right Set.inter_subset_right disjoint_compl_right)

Result:
no goals

Proof state:
α : Type u_1
inst✝ : MeasurableSpace α
j₁ j₂ : JordanDecomposition α
hj : j₁.toSignedMeasure = j₂.toSignedMeasure
S : Set α
hS₁ : MeasurableSet S
hS₂ : j₁.toSignedMeasure ≤[S] 0
hS₃ : 0 ≤[Sᶜ] j₁.toSignedMeasure
hS₄ : j₁.posPart S = 0
hS₅ : j₁.negPart Sᶜ = 0
T : Set α
hT₁ : MeasurableSet T
hT₂ : j₁.toSignedMeasure ≤[T] 0
hT₃ : 0 ≤[Tᶜ] j₁.toSignedMeasure
hT₄ : j₂.posPart T = 0
hT₅ : j₂.negPart Tᶜ = 0
hST₁ : ↑j₁.toSignedMeasure (symmDiff Sᶜ Tᶜ) = 0
i : Set α
hi : MeasurableSet i
⊢ (j₁.posPart i).toReal = (j₁.posPart (i ∩ Sᶜ)).toReal

Tactic:
conv_lhs => rw [← Set.inter_union_compl i S]

Result:
α : Type u_1
inst✝ : MeasurableSpace α
j₁ j₂ : JordanDecomposition α
hj : j₁.toSignedMeasure = j₂.toSignedMeasure
S : Set α
hS₁ : MeasurableSet S
hS₂ : j₁.toSignedMeasure ≤[S] 0
hS₃ : 0 ≤[Sᶜ] j₁.toSignedMeasure
hS₄ : j₁.posPart S = 0
hS₅ : j₁.negPart Sᶜ = 0
T : Set α
hT₁ : MeasurableSet T
hT₂ : j₁.toSignedMeasure ≤[T] 0
hT₃ : 0 ≤[Tᶜ] j₁.toSignedMeasure
hT₄ : j₂.posPart T = 0
hT₅ : j₂.negPart Tᶜ = 0
hST₁ : ↑j₁.toSignedMeasure (symmDiff Sᶜ Tᶜ) = 0
i : Set α
hi : MeasurableSet i
⊢ (j₁.posPart (i ∩ S ∪ i ∩ Sᶜ)).toReal = (j₁.posPart (i ∩ Sᶜ)).toReal

Proof state:
case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.h
α : Type u_1
inst✝ : MeasurableSpace α
j₁ j₂ : JordanDecomposition α
hj : j₁.toSignedMeasure = j₂.toSignedMeasure
S : Set α
hS₁ : MeasurableSet S
hS₂ : j₁.toSignedMeasure ≤[S] 0
hS₃ : 0 ≤[Sᶜ] j₁.toSignedMeasure
hS₄ : j₁.posPart S = 0
hS₅ : j₁.negPart Sᶜ = 0
T : Set α
hT₁ : MeasurableSet T
hT₂ : j₁.toSignedMeasure ≤[T] 0
hT₃ : 0 ≤[Tᶜ] j₁.toSignedMeasure
hT₄ : j₂.posPart T = 0
hT₅ : j₂.negPart Tᶜ = 0
hST₁ : ↑j₁.toSignedMeasure (symmDiff Sᶜ Tᶜ) = 0
i : Set α
hi : MeasurableSet i
hμ₁ : (j₁.posPart i).toReal = ↑j₁.toSignedMeasure (i ∩ Sᶜ)
hμ₂ : (j₂.posPart i).toReal = ↑j₂.toSignedMeasure (i ∩ Tᶜ)
⊢ ↑j₁.toSignedMeasure (i ∩ Sᶜ) = ↑j₁.toSignedMeasure (i ∩ Tᶜ)

Tactic:
exact of_inter_eq_of_symmDiff_eq_zero_positive hS₁.compl hT₁.compl hi hS₃ hT₃ hST₁

Result:
no goals

Proof state:
α : Type u_1
inst✝ : MeasurableSpace α
j₁ j₂ : JordanDecomposition α
hj : j₁.toSignedMeasure = j₂.toSignedMeasure
S : Set α
hS₁ : MeasurableSet S
hS₂ : j₁.toSignedMeasure ≤[S] 0
hS₃ : 0 ≤[Sᶜ] j₁.toSignedMeasure
hS₄ : j₁.posPart S = 0
hS₅ : j₁.negPart Sᶜ = 0
T : Set α
hT₁ : MeasurableSet T
hT₂ : j₁.toSignedMeasure ≤[T] 0
hT₃ : 0 ≤[Tᶜ] j₁.toSignedMeasure
hT₄ : j₂.posPart T = 0
hT₅ : j₂.negPart Tᶜ = 0
hST₁ : ↑j₁.toSignedMeasure (symmDiff Sᶜ Tᶜ) = 0
i : Set α
hi : MeasurableSet i
⊢ (j₁.posPart i).toReal = ↑j₁.toSignedMeasure (i ∩ Sᶜ)

Tactic:
rw [toSignedMeasure, toSignedMeasure_sub_apply (hi.inter hS₁.compl),
  show j₁.negPart (i ∩ Sᶜ) = 0 from
    nonpos_iff_eq_zero.1 (hS₅ ▸ measure_mono Set.inter_subset_right),
  ENNReal.zero_toReal, sub_zero]

Result:
α : Type u_1
inst✝ : MeasurableSpace α
j₁ j₂ : JordanDecomposition α
hj : j₁.toSignedMeasure = j₂.toSignedMeasure
S : Set α
hS₁ : MeasurableSet S
hS₂ : j₁.toSignedMeasure ≤[S] 0
hS₃ : 0 ≤[Sᶜ] j₁.toSignedMeasure
hS₄ : j₁.posPart S = 0
hS₅ : j₁.negPart Sᶜ = 0
T : Set α
hT₁ : MeasurableSet T
hT₂ : j₁.toSignedMeasure ≤[T] 0
hT₃ : 0 ≤[Tᶜ] j₁.toSignedMeasure
hT₄ : j₂.posPart T = 0
hT₅ : j₂.negPart Tᶜ = 0
hST₁ : ↑j₁.toSignedMeasure (symmDiff Sᶜ Tᶜ) = 0
i : Set α
hi : MeasurableSet i
⊢ (j₁.posPart i).toReal = (j₁.posPart (i ∩ Sᶜ)).toReal

Proof state:
case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro
α : Type u_1
inst✝ : MeasurableSpace α
j₁ j₂ : JordanDecomposition α
hj : j₁.toSignedMeasure = j₂.toSignedMeasure
S : Set α
hS₁ : MeasurableSet S
hS₂ : j₁.toSignedMeasure ≤[S] 0
hS₃ : 0 ≤[Sᶜ] j₁.toSignedMeasure
hS₄ : j₁.posPart S = 0
hS₅ : j₁.negPart Sᶜ = 0
T : Set α
hT₁ : MeasurableSet T
hT₂ : j₁.toSignedMeasure ≤[T] 0
hT₃ : 0 ≤[Tᶜ] j₁.toSignedMeasure
hT₄ : j₂.posPart T = 0
hT₅ : j₂.negPart Tᶜ = 0
hST₁ : ↑j₁.toSignedMeasure (symmDiff Sᶜ Tᶜ) = 0
⊢ j₁.posPart = j₂.posPart

Tactic:
ext1 i hi

Result:
case intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.intro.h
α : Type u_1
inst✝ : MeasurableSpace α
j₁ j₂ : JordanDecomposition α
hj : j₁.toSignedMeasure = j₂.toSignedMeasure
S : Set α
hS₁ : MeasurableSet S
hS₂ : j₁.toSignedMeasure ≤[S] 0
hS₃ : 0 ≤[Sᶜ] j₁.toSignedMeasure
hS₄ : j₁.posPart S = 0
hS₅ : j₁.negPart Sᶜ = 0
T : Set α
hT₁ : MeasurableSet T
hT₂ : j₁.toSignedMeasure ≤[T] 0
hT₃ : 0 ≤[Tᶜ] j₁.toSignedMeasure
hT₄ : j₂.posPart T = 0
hT₅ : j₂.negPart Tᶜ = 0
hST₁ : ↑j₁.toSignedMeasure (symmDiff Sᶜ Tᶜ) = 0
i : Set α
hi : MeasurableSet i
⊢ j₁.posPart i = j₂.posPart i