l3lab/ntp-mathlib huggingface dataset:
/-- **The Lebesgue Decomposition theorem between a signed measure and a measure**:
Given a signed measure `s` and a σ-finite measure `μ`, there exist a signed measure `t` and a
measurable and integrable function `f`, such that `t` is mutually singular with respect to `μ`
and `s = t + μ.withDensityᵥ f`. In this case `t = s.singularPart μ` and
`f = s.rnDeriv μ`. -/
theorem singularPart_add_withDensity_rnDeriv_eq [s.HaveLebesgueDecomposition μ] :
    s.singularPart μ + μ.withDensityᵥ (s.rnDeriv μ) = s := by
  conv_rhs =>
    rw [← toSignedMeasure_toJordanDecomposition s, JordanDecomposition.toSignedMeasure]
  rw [singularPart, rnDeriv,
    withDensityᵥ_sub' (integrable_toReal_of_lintegral_ne_top _ _)
      (integrable_toReal_of_lintegral_ne_top _ _),
    withDensityᵥ_toReal, withDensityᵥ_toReal, sub_eq_add_neg, sub_eq_add_neg,
    add_comm (s.toJordanDecomposition.posPart.singularPart μ).toSignedMeasure, ← add_assoc,
    add_assoc (-(s.toJordanDecomposition.negPart.singularPart μ).toSignedMeasure),
    ← toSignedMeasure_add, add_comm, ← add_assoc, ← neg_add, ← toSignedMeasure_add, add_comm,
    ← sub_eq_add_neg]
  convert rfl
  -- `convert rfl` much faster than `congr`
  · exact s.toJordanDecomposition.posPart.haveLebesgueDecomposition_add μ
  · rw [add_comm]
    exact s.toJordanDecomposition.negPart.haveLebesgueDecomposition_add μ
  all_goals
    first
    | 

Proof state:
case hfm
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
inst✝ : HaveLebesgueDecomposition s μ
⊢ AEMeasurable fun x => Measure.rnDeriv (toJordanDecomposition s).posPart μ x

Next tactic:
exact (lintegral_rnDeriv_lt_top _ _).ne
/-- **The Lebesgue Decomposition theorem between a signed measure and a measure**:
Given a signed measure `s` and a σ-finite measure `μ`, there exist a signed measure `t` and a
measurable and integrable function `f`, such that `t` is mutually singular with respect to `μ`
and `s = t + μ.withDensityᵥ f`. In this case `t = s.singularPart μ` and
`f = s.rnDeriv μ`. -/
theorem singularPart_add_withDensity_rnDeriv_eq [s.HaveLebesgueDecomposition μ] :
    s.singularPart μ + μ.withDensityᵥ (s.rnDeriv μ) = s := by
  conv_rhs =>
    rw [← toSignedMeasure_toJordanDecomposition s, JordanDecomposition.toSignedMeasure]
  rw [singularPart, rnDeriv,
    withDensityᵥ_sub' (integrable_toReal_of_lintegral_ne_top _ _)
      (integrable_toReal_of_lintegral_ne_top _ _),
    withDensityᵥ_toReal, withDensityᵥ_toReal, sub_eq_add_neg, sub_eq_add_neg,
    add_comm (s.toJordanDecomposition.posPart.singularPart μ).toSignedMeasure, ← add_assoc,
    add_assoc (-(s.toJordanDecomposition.negPart.singularPart μ).toSignedMeasure),
    ← toSignedMeasure_add, add_comm, ← add_assoc, ← neg_add, ← toSignedMeasure_add, add_comm,
    ← sub_eq_add_neg]
  convert rfl
  -- `convert rfl` much faster than `congr`
  · exact s.toJordanDecomposition.posPart.haveLebesgueDecomposition_add μ
  · rw [add_comm]
    exact s.toJordanDecomposition.negPart.haveLebesgueDecomposition_add μ
  all_goals
    first
    | exact (lintegral_rnDeriv_lt_top _ _).ne
    | 

Proof state:
case hfm
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
inst✝ : HaveLebesgueDecomposition s μ
⊢ AEMeasurable fun x => Measure.rnDeriv (toJordanDecomposition s).posPart μ x

Next tactic:
measurability
/-- **The Lebesgue Decomposition theorem between a signed measure and a measure**:
Given a signed measure `s` and a σ-finite measure `μ`, there exist a signed measure `t` and a
measurable and integrable function `f`, such that `t` is mutually singular with respect to `μ`
and `s = t + μ.withDensityᵥ f`. In this case `t = s.singularPart μ` and
`f = s.rnDeriv μ`. -/
theorem singularPart_add_withDensity_rnDeriv_eq [s.HaveLebesgueDecomposition μ] :
    s.singularPart μ + μ.withDensityᵥ (s.rnDeriv μ) = s := by
  conv_rhs =>
    rw [← toSignedMeasure_toJordanDecomposition s, JordanDecomposition.toSignedMeasure]
  rw [singularPart, rnDeriv,
    withDensityᵥ_sub' (integrable_toReal_of_lintegral_ne_top _ _)
      (integrable_toReal_of_lintegral_ne_top _ _),
    withDensityᵥ_toReal, withDensityᵥ_toReal, sub_eq_add_neg, sub_eq_add_neg,
    add_comm (s.toJordanDecomposition.posPart.singularPart μ).toSignedMeasure, ← add_assoc,
    add_assoc (-(s.toJordanDecomposition.negPart.singularPart μ).toSignedMeasure),
    ← toSignedMeasure_add, add_comm, ← add_assoc, ← neg_add, ← toSignedMeasure_add, add_comm,
    ← sub_eq_add_neg]
  convert rfl
  -- `convert rfl` much faster than `congr`
  · exact s.toJordanDecomposition.posPart.haveLebesgueDecomposition_add μ
  · rw [add_comm]
    exact s.toJordanDecomposition.negPart.haveLebesgueDecomposition_add μ
  all_goals
    

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
inst✝ : HaveLebesgueDecomposition s μ
⊢ AEMeasurable fun x => Measure.rnDeriv (toJordanDecomposition s).posPart μ x

Next tactic:
first
    | exact (lintegral_rnDeriv_lt_top _ _).ne
    | measurability
/-- **The Lebesgue Decomposition theorem between a signed measure and a measure**:
Given a signed measure `s` and a σ-finite measure `μ`, there exist a signed measure `t` and a
measurable and integrable function `f`, such that `t` is mutually singular with respect to `μ`
and `s = t + μ.withDensityᵥ f`. In this case `t = s.singularPart μ` and
`f = s.rnDeriv μ`. -/
theorem singularPart_add_withDensity_rnDeriv_eq [s.HaveLebesgueDecomposition μ] :
    s.singularPart μ + μ.withDensityᵥ (s.rnDeriv μ) = s := by
  conv_rhs =>
    rw [← toSignedMeasure_toJordanDecomposition s, JordanDecomposition.toSignedMeasure]
  rw [singularPart, rnDeriv,
    withDensityᵥ_sub' (integrable_toReal_of_lintegral_ne_top _ _)
      (integrable_toReal_of_lintegral_ne_top _ _),
    withDensityᵥ_toReal, withDensityᵥ_toReal, sub_eq_add_neg, sub_eq_add_neg,
    add_comm (s.toJordanDecomposition.posPart.singularPart μ).toSignedMeasure, ← add_assoc,
    add_assoc (-(s.toJordanDecomposition.negPart.singularPart μ).toSignedMeasure),
    ← toSignedMeasure_add, add_comm, ← add_assoc, ← neg_add, ← toSignedMeasure_add, add_comm,
    ← sub_eq_add_neg]
  convert rfl
  -- `convert rfl` much faster than `congr`
  · exact s.toJordanDecomposition.posPart.haveLebesgueDecomposition_add μ
  · rw [add_comm]
    exact s.toJordanDecomposition.negPart.haveLebesgueDecomposition_add μ
  all_goals
    first
    | 

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
inst✝ : HaveLebesgueDecomposition s μ
⊢ AEMeasurable fun x => Measure.rnDeriv (toJordanDecomposition s).posPart μ x

Next tactic:
exact (lintegral_rnDeriv_lt_top _ _).ne
/-- **The Lebesgue Decomposition theorem between a signed measure and a measure**:
Given a signed measure `s` and a σ-finite measure `μ`, there exist a signed measure `t` and a
measurable and integrable function `f`, such that `t` is mutually singular with respect to `μ`
and `s = t + μ.withDensityᵥ f`. In this case `t = s.singularPart μ` and
`f = s.rnDeriv μ`. -/
theorem singularPart_add_withDensity_rnDeriv_eq [s.HaveLebesgueDecomposition μ] :
    s.singularPart μ + μ.withDensityᵥ (s.rnDeriv μ) = s := by
  conv_rhs =>
    rw [← toSignedMeasure_toJordanDecomposition s, JordanDecomposition.toSignedMeasure]
  rw [singularPart, rnDeriv,
    withDensityᵥ_sub' (integrable_toReal_of_lintegral_ne_top _ _)
      (integrable_toReal_of_lintegral_ne_top _ _),
    withDensityᵥ_toReal, withDensityᵥ_toReal, sub_eq_add_neg, sub_eq_add_neg,
    add_comm (s.toJordanDecomposition.posPart.singularPart μ).toSignedMeasure, ← add_assoc,
    add_assoc (-(s.toJordanDecomposition.negPart.singularPart μ).toSignedMeasure),
    ← toSignedMeasure_add, add_comm, ← add_assoc, ← neg_add, ← toSignedMeasure_add, add_comm,
    ← sub_eq_add_neg]
  convert rfl
  -- `convert rfl` much faster than `congr`
  · exact s.toJordanDecomposition.posPart.haveLebesgueDecomposition_add μ
  · rw [add_comm]
    exact s.toJordanDecomposition.negPart.haveLebesgueDecomposition_add μ
  all_goals
    first
    | exact (lintegral_rnDeriv_lt_top _ _).ne
    | 

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
inst✝ : HaveLebesgueDecomposition s μ
⊢ AEMeasurable fun x => Measure.rnDeriv (toJordanDecomposition s).posPart μ x

Next tactic:
measurability
/-- **The Lebesgue Decomposition theorem between a signed measure and a measure**:
Given a signed measure `s` and a σ-finite measure `μ`, there exist a signed measure `t` and a
measurable and integrable function `f`, such that `t` is mutually singular with respect to `μ`
and `s = t + μ.withDensityᵥ f`. In this case `t = s.singularPart μ` and
`f = s.rnDeriv μ`. -/
theorem singularPart_add_withDensity_rnDeriv_eq [s.HaveLebesgueDecomposition μ] :
    s.singularPart μ + μ.withDensityᵥ (s.rnDeriv μ) = s := by
  conv_rhs =>
    rw [← toSignedMeasure_toJordanDecomposition s, JordanDecomposition.toSignedMeasure]
  rw [singularPart, rnDeriv,
    withDensityᵥ_sub' (integrable_toReal_of_lintegral_ne_top _ _)
      (integrable_toReal_of_lintegral_ne_top _ _),
    withDensityᵥ_toReal, withDensityᵥ_toReal, sub_eq_add_neg, sub_eq_add_neg,
    add_comm (s.toJordanDecomposition.posPart.singularPart μ).toSignedMeasure, ← add_assoc,
    add_assoc (-(s.toJordanDecomposition.negPart.singularPart μ).toSignedMeasure),
    ← toSignedMeasure_add, add_comm, ← add_assoc, ← neg_add, ← toSignedMeasure_add, add_comm,
    ← sub_eq_add_neg]
  convert rfl
  -- `convert rfl` much faster than `congr`
  · exact s.toJordanDecomposition.posPart.haveLebesgueDecomposition_add μ
  · rw [add_comm]
    exact s.toJordanDecomposition.negPart.haveLebesgueDecomposition_add μ
  all_goals
    

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
inst✝ : HaveLebesgueDecomposition s μ
⊢ ∫⁻ (x : α), Measure.rnDeriv (toJordanDecomposition s).posPart μ x ∂μ ≠ ⊤

Next tactic:
first
    | exact (lintegral_rnDeriv_lt_top _ _).ne
    | measurability
/-- **The Lebesgue Decomposition theorem between a signed measure and a measure**:
Given a signed measure `s` and a σ-finite measure `μ`, there exist a signed measure `t` and a
measurable and integrable function `f`, such that `t` is mutually singular with respect to `μ`
and `s = t + μ.withDensityᵥ f`. In this case `t = s.singularPart μ` and
`f = s.rnDeriv μ`. -/
theorem singularPart_add_withDensity_rnDeriv_eq [s.HaveLebesgueDecomposition μ] :
    s.singularPart μ + μ.withDensityᵥ (s.rnDeriv μ) = s := by
  conv_rhs =>
    rw [← toSignedMeasure_toJordanDecomposition s, JordanDecomposition.toSignedMeasure]
  rw [singularPart, rnDeriv,
    withDensityᵥ_sub' (integrable_toReal_of_lintegral_ne_top _ _)
      (integrable_toReal_of_lintegral_ne_top _ _),
    withDensityᵥ_toReal, withDensityᵥ_toReal, sub_eq_add_neg, sub_eq_add_neg,
    add_comm (s.toJordanDecomposition.posPart.singularPart μ).toSignedMeasure, ← add_assoc,
    add_assoc (-(s.toJordanDecomposition.negPart.singularPart μ).toSignedMeasure),
    ← toSignedMeasure_add, add_comm, ← add_assoc, ← neg_add, ← toSignedMeasure_add, add_comm,
    ← sub_eq_add_neg]
  convert rfl
  -- `convert rfl` much faster than `congr`
  · exact s.toJordanDecomposition.posPart.haveLebesgueDecomposition_add μ
  · rw [add_comm]
    exact s.toJordanDecomposition.negPart.haveLebesgueDecomposition_add μ
  all_goals
    first
    | 

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
inst✝ : HaveLebesgueDecomposition s μ
⊢ ∫⁻ (x : α), Measure.rnDeriv (toJordanDecomposition s).posPart μ x ∂μ ≠ ⊤

Next tactic:
exact (lintegral_rnDeriv_lt_top _ _).ne
/-- **The Lebesgue Decomposition theorem between a signed measure and a measure**:
Given a signed measure `s` and a σ-finite measure `μ`, there exist a signed measure `t` and a
measurable and integrable function `f`, such that `t` is mutually singular with respect to `μ`
and `s = t + μ.withDensityᵥ f`. In this case `t = s.singularPart μ` and
`f = s.rnDeriv μ`. -/
theorem singularPart_add_withDensity_rnDeriv_eq [s.HaveLebesgueDecomposition μ] :
    s.singularPart μ + μ.withDensityᵥ (s.rnDeriv μ) = s := by
  conv_rhs =>
    rw [← toSignedMeasure_toJordanDecomposition s, JordanDecomposition.toSignedMeasure]
  rw [singularPart, rnDeriv,
    withDensityᵥ_sub' (integrable_toReal_of_lintegral_ne_top _ _)
      (integrable_toReal_of_lintegral_ne_top _ _),
    withDensityᵥ_toReal, withDensityᵥ_toReal, sub_eq_add_neg, sub_eq_add_neg,
    add_comm (s.toJordanDecomposition.posPart.singularPart μ).toSignedMeasure, ← add_assoc,
    add_assoc (-(s.toJordanDecomposition.negPart.singularPart μ).toSignedMeasure),
    ← toSignedMeasure_add, add_comm, ← add_assoc, ← neg_add, ← toSignedMeasure_add, add_comm,
    ← sub_eq_add_neg]
  convert rfl
  -- `convert rfl` much faster than `congr`
  · exact s.toJordanDecomposition.posPart.haveLebesgueDecomposition_add μ
  · rw [add_comm]
    exact s.toJordanDecomposition.negPart.haveLebesgueDecomposition_add μ
  all_goals
    

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
inst✝ : HaveLebesgueDecomposition s μ
⊢ AEMeasurable fun x => Measure.rnDeriv (toJordanDecomposition s).negPart μ x

Next tactic:
first
    | exact (lintegral_rnDeriv_lt_top _ _).ne
    | measurability
/-- **The Lebesgue Decomposition theorem between a signed measure and a measure**:
Given a signed measure `s` and a σ-finite measure `μ`, there exist a signed measure `t` and a
measurable and integrable function `f`, such that `t` is mutually singular with respect to `μ`
and `s = t + μ.withDensityᵥ f`. In this case `t = s.singularPart μ` and
`f = s.rnDeriv μ`. -/
theorem singularPart_add_withDensity_rnDeriv_eq [s.HaveLebesgueDecomposition μ] :
    s.singularPart μ + μ.withDensityᵥ (s.rnDeriv μ) = s := by
  conv_rhs =>
    rw [← toSignedMeasure_toJordanDecomposition s, JordanDecomposition.toSignedMeasure]
  rw [singularPart, rnDeriv,
    withDensityᵥ_sub' (integrable_toReal_of_lintegral_ne_top _ _)
      (integrable_toReal_of_lintegral_ne_top _ _),
    withDensityᵥ_toReal, withDensityᵥ_toReal, sub_eq_add_neg, sub_eq_add_neg,
    add_comm (s.toJordanDecomposition.posPart.singularPart μ).toSignedMeasure, ← add_assoc,
    add_assoc (-(s.toJordanDecomposition.negPart.singularPart μ).toSignedMeasure),
    ← toSignedMeasure_add, add_comm, ← add_assoc, ← neg_add, ← toSignedMeasure_add, add_comm,
    ← sub_eq_add_neg]
  convert rfl
  -- `convert rfl` much faster than `congr`
  · exact s.toJordanDecomposition.posPart.haveLebesgueDecomposition_add μ
  · rw [add_comm]
    exact s.toJordanDecomposition.negPart.haveLebesgueDecomposition_add μ
  all_goals
    first
    | 

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
inst✝ : HaveLebesgueDecomposition s μ
⊢ AEMeasurable fun x => Measure.rnDeriv (toJordanDecomposition s).negPart μ x

Next tactic:
exact (lintegral_rnDeriv_lt_top _ _).ne
/-- **The Lebesgue Decomposition theorem between a signed measure and a measure**:
Given a signed measure `s` and a σ-finite measure `μ`, there exist a signed measure `t` and a
measurable and integrable function `f`, such that `t` is mutually singular with respect to `μ`
and `s = t + μ.withDensityᵥ f`. In this case `t = s.singularPart μ` and
`f = s.rnDeriv μ`. -/
theorem singularPart_add_withDensity_rnDeriv_eq [s.HaveLebesgueDecomposition μ] :
    s.singularPart μ + μ.withDensityᵥ (s.rnDeriv μ) = s := by
  conv_rhs =>
    rw [← toSignedMeasure_toJordanDecomposition s, JordanDecomposition.toSignedMeasure]
  rw [singularPart, rnDeriv,
    withDensityᵥ_sub' (integrable_toReal_of_lintegral_ne_top _ _)
      (integrable_toReal_of_lintegral_ne_top _ _),
    withDensityᵥ_toReal, withDensityᵥ_toReal, sub_eq_add_neg, sub_eq_add_neg,
    add_comm (s.toJordanDecomposition.posPart.singularPart μ).toSignedMeasure, ← add_assoc,
    add_assoc (-(s.toJordanDecomposition.negPart.singularPart μ).toSignedMeasure),
    ← toSignedMeasure_add, add_comm, ← add_assoc, ← neg_add, ← toSignedMeasure_add, add_comm,
    ← sub_eq_add_neg]
  convert rfl
  -- `convert rfl` much faster than `congr`
  · exact s.toJordanDecomposition.posPart.haveLebesgueDecomposition_add μ
  · rw [add_comm]
    exact s.toJordanDecomposition.negPart.haveLebesgueDecomposition_add μ
  all_goals
    first
    | exact (lintegral_rnDeriv_lt_top _ _).ne
    | 

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
inst✝ : HaveLebesgueDecomposition s μ
⊢ AEMeasurable fun x => Measure.rnDeriv (toJordanDecomposition s).negPart μ x

Next tactic:
measurability
/-- **The Lebesgue Decomposition theorem between a signed measure and a measure**:
Given a signed measure `s` and a σ-finite measure `μ`, there exist a signed measure `t` and a
measurable and integrable function `f`, such that `t` is mutually singular with respect to `μ`
and `s = t + μ.withDensityᵥ f`. In this case `t = s.singularPart μ` and
`f = s.rnDeriv μ`. -/
theorem singularPart_add_withDensity_rnDeriv_eq [s.HaveLebesgueDecomposition μ] :
    s.singularPart μ + μ.withDensityᵥ (s.rnDeriv μ) = s := by
  conv_rhs =>
    rw [← toSignedMeasure_toJordanDecomposition s, JordanDecomposition.toSignedMeasure]
  rw [singularPart, rnDeriv,
    withDensityᵥ_sub' (integrable_toReal_of_lintegral_ne_top _ _)
      (integrable_toReal_of_lintegral_ne_top _ _),
    withDensityᵥ_toReal, withDensityᵥ_toReal, sub_eq_add_neg, sub_eq_add_neg,
    add_comm (s.toJordanDecomposition.posPart.singularPart μ).toSignedMeasure, ← add_assoc,
    add_assoc (-(s.toJordanDecomposition.negPart.singularPart μ).toSignedMeasure),
    ← toSignedMeasure_add, add_comm, ← add_assoc, ← neg_add, ← toSignedMeasure_add, add_comm,
    ← sub_eq_add_neg]
  convert rfl
  -- `convert rfl` much faster than `congr`
  · exact s.toJordanDecomposition.posPart.haveLebesgueDecomposition_add μ
  · rw [add_comm]
    exact s.toJordanDecomposition.negPart.haveLebesgueDecomposition_add μ
  all_goals
    

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
inst✝ : HaveLebesgueDecomposition s μ
⊢ ∫⁻ (x : α), Measure.rnDeriv (toJordanDecomposition s).negPart μ x ∂μ ≠ ⊤

Next tactic:
first
    | exact (lintegral_rnDeriv_lt_top _ _).ne
    | measurability
/-- **The Lebesgue Decomposition theorem between a signed measure and a measure**:
Given a signed measure `s` and a σ-finite measure `μ`, there exist a signed measure `t` and a
measurable and integrable function `f`, such that `t` is mutually singular with respect to `μ`
and `s = t + μ.withDensityᵥ f`. In this case `t = s.singularPart μ` and
`f = s.rnDeriv μ`. -/
theorem singularPart_add_withDensity_rnDeriv_eq [s.HaveLebesgueDecomposition μ] :
    s.singularPart μ + μ.withDensityᵥ (s.rnDeriv μ) = s := by
  conv_rhs =>
    rw [← toSignedMeasure_toJordanDecomposition s, JordanDecomposition.toSignedMeasure]
  rw [singularPart, rnDeriv,
    withDensityᵥ_sub' (integrable_toReal_of_lintegral_ne_top _ _)
      (integrable_toReal_of_lintegral_ne_top _ _),
    withDensityᵥ_toReal, withDensityᵥ_toReal, sub_eq_add_neg, sub_eq_add_neg,
    add_comm (s.toJordanDecomposition.posPart.singularPart μ).toSignedMeasure, ← add_assoc,
    add_assoc (-(s.toJordanDecomposition.negPart.singularPart μ).toSignedMeasure),
    ← toSignedMeasure_add, add_comm, ← add_assoc, ← neg_add, ← toSignedMeasure_add, add_comm,
    ← sub_eq_add_neg]
  convert rfl
  -- `convert rfl` much faster than `congr`
  · exact s.toJordanDecomposition.posPart.haveLebesgueDecomposition_add μ
  · rw [add_comm]
    exact s.toJordanDecomposition.negPart.haveLebesgueDecomposition_add μ
  all_goals
    first
    | 

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
inst✝ : HaveLebesgueDecomposition s μ
⊢ ∫⁻ (x : α), Measure.rnDeriv (toJordanDecomposition s).negPart μ x ∂μ ≠ ⊤

Next tactic:
exact (lintegral_rnDeriv_lt_top _ _).ne
theorem jordanDecomposition_add_withDensity_mutuallySingular {f : α → ℝ} (hf : Measurable f)
    (htμ : t ⟂ᵥ μ.toENNRealVectorMeasure) :
    (t.toJordanDecomposition.posPart + μ.withDensity fun x : α => ENNReal.ofReal (f x)) ⟂ₘ
      t.toJordanDecomposition.negPart + μ.withDensity fun x : α => ENNReal.ofReal (-f x) := by
  

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
f : α → ℝ
hf : Measurable f
htμ : t ⟂ᵥ toENNRealVectorMeasure μ
⊢ ((toJordanDecomposition t).posPart + withDensity μ fun x => ENNReal.ofReal (f x)) ⟂ₘ
    (toJordanDecomposition t).negPart + withDensity μ fun x => ENNReal.ofReal (-f x)

Next tactic:
rw [mutuallySingular_ennreal_iff, totalVariation_mutuallySingular_iff,
    VectorMeasure.ennrealToMeasure_toENNRealVectorMeasure] at htμ
theorem jordanDecomposition_add_withDensity_mutuallySingular {f : α → ℝ} (hf : Measurable f)
    (htμ : t ⟂ᵥ μ.toENNRealVectorMeasure) :
    (t.toJordanDecomposition.posPart + μ.withDensity fun x : α => ENNReal.ofReal (f x)) ⟂ₘ
      t.toJordanDecomposition.negPart + μ.withDensity fun x : α => ENNReal.ofReal (-f x) := by
  rw [mutuallySingular_ennreal_iff, totalVariation_mutuallySingular_iff,
    VectorMeasure.ennrealToMeasure_toENNRealVectorMeasure] at htμ
  

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
f : α → ℝ
hf : Measurable f
htμ : (toJordanDecomposition t).posPart ⟂ₘ μ ∧ (toJordanDecomposition t).negPart ⟂ₘ μ
⊢ ((toJordanDecomposition t).posPart + withDensity μ fun x => ENNReal.ofReal (f x)) ⟂ₘ
    (toJordanDecomposition t).negPart + withDensity μ fun x => ENNReal.ofReal (-f x)

Next tactic:
exact
    ((JordanDecomposition.mutuallySingular _).add_right
          (htμ.1.mono_ac (refl _) (withDensity_absolutelyContinuous _ _))).add_left
      ((htμ.2.symm.mono_ac (withDensity_absolutelyContinuous _ _) (refl _)).add_right
        (withDensity_ofReal_mutuallySingular hf))
theorem toJordanDecomposition_eq_of_eq_add_withDensity {f : α → ℝ} (hf : Measurable f)
    (hfi : Integrable f μ) (htμ : t ⟂ᵥ μ.toENNRealVectorMeasure) (hadd : s = t + μ.withDensityᵥ f) :
    s.toJordanDecomposition =
      @JordanDecomposition.mk α _
        (t.toJordanDecomposition.posPart + μ.withDensity fun x => ENNReal.ofReal (f x))
        (t.toJordanDecomposition.negPart + μ.withDensity fun x => ENNReal.ofReal (-f x))
        (by 

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
f : α → ℝ
hf : Measurable f
hfi : Integrable f
htμ : t ⟂ᵥ toENNRealVectorMeasure μ
hadd : s = t + withDensityᵥ μ f
⊢ IsFiniteMeasure ((toJordanDecomposition t).posPart + withDensity μ fun x => ENNReal.ofReal (f x))

Next tactic:
haveI := isFiniteMeasure_withDensity_ofReal hfi.2
theorem toJordanDecomposition_eq_of_eq_add_withDensity {f : α → ℝ} (hf : Measurable f)
    (hfi : Integrable f μ) (htμ : t ⟂ᵥ μ.toENNRealVectorMeasure) (hadd : s = t + μ.withDensityᵥ f) :
    s.toJordanDecomposition =
      @JordanDecomposition.mk α _
        (t.toJordanDecomposition.posPart + μ.withDensity fun x => ENNReal.ofReal (f x))
        (t.toJordanDecomposition.negPart + μ.withDensity fun x => ENNReal.ofReal (-f x))
        (by haveI := isFiniteMeasure_withDensity_ofReal hfi.2; 

Proof state:
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ ν : Measure α
s t : SignedMeasure α
f : α → ℝ
hf : Measurable f
hfi : Integrable f
htμ : t ⟂ᵥ toENNRealVectorMeasure μ
hadd : s = t + withDensityᵥ μ f
this : IsFiniteMeasure (withDensity μ fun x => ENNReal.ofReal (f x))
⊢ IsFiniteMeasure ((toJordanDecomposition t).posPart + withDensity μ fun x => ENNReal.ofReal (f x))

Next tactic:
infer_instance