Theorem: MeasureTheory.Measure.rnDeriv_smul_right
File: Mathlib/MeasureTheory/Decomposition/Lebesgue.lean

tactic: refine (absolutelyContinuous_smul <| ENNReal.coe_ne_zero.2 hr).ae_le
  (?_ : ν.rnDeriv (r • μ) =ᵐ[r • μ] r⁻¹ • ν.rnDeriv μ)
state_before: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ ν.rnDeriv (r • μ) =ᶠ[ae μ] r⁻¹ • ν.rnDeriv μ
state_after: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ ν.rnDeriv (r • μ) =ᶠ[ae (r • μ)] r⁻¹ • ν.rnDeriv μ

tactic: rw [← withDensity_eq_iff]
state_before: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ ν.rnDeriv (r • μ) =ᶠ[ae (r • μ)] r⁻¹ • ν.rnDeriv μ
state_after: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ (r • μ).withDensity (ν.rnDeriv (r • μ)) = (r • μ).withDensity (r⁻¹ • ν.rnDeriv μ)

case hf
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ AEMeasurable (ν.rnDeriv (r • μ)) (r • μ)

case hg
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ AEMeasurable (r⁻¹ • ν.rnDeriv μ) (r • μ)

case hfi
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ ∫⁻ (x : α), ν.rnDeriv (r • μ) x ∂r • μ ≠ ⊤

tactic: rotate_left
state_before: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ (r • μ).withDensity (ν.rnDeriv (r • μ)) = (r • μ).withDensity (r⁻¹ • ν.rnDeriv μ)

case hf
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ AEMeasurable (ν.rnDeriv (r • μ)) (r • μ)

case hg
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ AEMeasurable (r⁻¹ • ν.rnDeriv μ) (r • μ)

case hfi
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ ∫⁻ (x : α), ν.rnDeriv (r • μ) x ∂r • μ ≠ ⊤
state_after: case hf
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ AEMeasurable (ν.rnDeriv (r • μ)) (r • μ)

case hg
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ AEMeasurable (r⁻¹ • ν.rnDeriv μ) (r • μ)

case hfi
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ ∫⁻ (x : α), ν.rnDeriv (r • μ) x ∂r • μ ≠ ⊤

α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ (r • μ).withDensity (ν.rnDeriv (r • μ)) = (r • μ).withDensity (r⁻¹ • ν.rnDeriv μ)

tactic: exact (measurable_rnDeriv _ _).aemeasurable
state_before: case hf
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ AEMeasurable (ν.rnDeriv (r • μ)) (r • μ)
state_after: no goals

tactic: exact (measurable_rnDeriv _ _).aemeasurable.const_smul _
state_before: case hg
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ AEMeasurable (r⁻¹ • ν.rnDeriv μ) (r • μ)
state_after: no goals

tactic: exact (lintegral_rnDeriv_lt_top ν _).ne
state_before: case hfi
α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ ∫⁻ (x : α), ν.rnDeriv (r • μ) x ∂r • μ ≠ ⊤
state_after: no goals

tactic: simp_rw [ENNReal.smul_def]
state_before: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ (r • μ).withDensity (ν.rnDeriv (r • μ)) = (r • μ).withDensity (r⁻¹ • ν.rnDeriv μ)
state_after: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ (↑r • μ).withDensity (ν.rnDeriv (↑r • μ)) = (↑r • μ).withDensity (↑r⁻¹ • ν.rnDeriv μ)

tactic: rw [withDensity_smul _ (measurable_rnDeriv _ _)]
state_before: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ (↑r • μ).withDensity (ν.rnDeriv (↑r • μ)) = (↑r • μ).withDensity (↑r⁻¹ • ν.rnDeriv μ)
state_after: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ (↑r • μ).withDensity (ν.rnDeriv (↑r • μ)) = ↑r⁻¹ • (↑r • μ).withDensity (ν.rnDeriv μ)

tactic: suffices ν.singularPart (r • μ) + withDensity (r • μ) (rnDeriv ν (r • μ))
    = ν.singularPart (r • μ) + r⁻¹ • withDensity (r • μ) (rnDeriv ν μ) by
  rwa [add_right_inj] at this
state_before: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ (↑r • μ).withDensity (ν.rnDeriv (↑r • μ)) = ↑r⁻¹ • (↑r • μ).withDensity (ν.rnDeriv μ)
state_after: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ ν.singularPart (r • μ) + (r • μ).withDensity (ν.rnDeriv (r • μ)) =
    ν.singularPart (r • μ) + r⁻¹ • (r • μ).withDensity (ν.rnDeriv μ)

tactic: rw [← ν.haveLebesgueDecomposition_add (r • μ), singularPart_smul_right _ _ _ hr,
  ENNReal.smul_def r, withDensity_smul_measure, ← ENNReal.smul_def, ← smul_assoc,
  smul_eq_mul, inv_mul_cancel hr, one_smul]
state_before: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ ν.singularPart (r • μ) + (r • μ).withDensity (ν.rnDeriv (r • μ)) =
    ν.singularPart (r • μ) + r⁻¹ • (r • μ).withDensity (ν.rnDeriv μ)
state_after: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ ν = ν.singularPart μ + μ.withDensity (ν.rnDeriv μ)

tactic: exact ν.haveLebesgueDecomposition_add μ
state_before: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
⊢ ν = ν.singularPart μ + μ.withDensity (ν.rnDeriv μ)
state_after: no goals

tactic: rwa [add_right_inj] at this
state_before: α : Type u_1
β : Type u_2
m : MeasurableSpace α
μ✝ ν✝ ν μ : Measure α
inst✝¹ : IsFiniteMeasure ν
inst✝ : ν.HaveLebesgueDecomposition μ
r : ℝ≥0
hr : r ≠ 0
this :
  ν.singularPart (r • μ) + (r • μ).withDensity (ν.rnDeriv (r • μ)) =
    ν.singularPart (r • μ) + r⁻¹ • (r • μ).withDensity (ν.rnDeriv μ)
⊢ (↑r • μ).withDensity (ν.rnDeriv (↑r • μ)) = ↑r⁻¹ • (↑r • μ).withDensity (ν.rnDeriv μ)
state_after: no goals