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

Proof steps:
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: 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 (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: 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
⊢ (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: rotate_left