-- Mathlib/Probability/Kernel/RadonNikodym.lean
lemma measure_mutuallySingularSetSlice (κ η : Kernel α γ) [IsFiniteKernel κ] [IsFiniteKernel η]
    (a : α) :
    η a (mutuallySingularSetSlice κ η a) = 0

Proof state:
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ ∀ᵐ (x : γ) ∂(κ + η) a, x ∈ {x | 1 ≤ κ.rnDerivAux (κ + η) a x} → ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x) = 0 x

Tactic:
refine ae_of_all _ (fun x hx ↦ ?_)

Result:
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
x : γ
hx : x ∈ {x | 1 ≤ κ.rnDerivAux (κ + η) a x}
⊢ ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x) = 0 x

Proof state:
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
x : γ
hx : x ∈ {x | 1 ≤ κ.rnDerivAux (κ + η) a x}
⊢ ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x) = 0 x

Tactic:
simp only [mem_setOf_eq] at hx

Result:
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
x : γ
hx : 1 ≤ κ.rnDerivAux (κ + η) a x
⊢ ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x) = 0 x

Proof state:
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ ∀ᵐ (x : γ) ∂(κ + η) a, x ∈ {x | 1 ≤ κ.rnDerivAux (κ + η) a x} → ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x) = 0 x

α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ MeasurableSet {x | ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x) = 0 x}

α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ Measurable fun b => ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a b)

case hf
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ Measurable (Function.uncurry fun a x => ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x))

Tactic:
rotate_left

Result:
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ MeasurableSet {x | ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x) = 0 x}

α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ Measurable fun b => ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a b)

case hf
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ Measurable (Function.uncurry fun a x => ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x))

α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ ∀ᵐ (x : γ) ∂(κ + η) a, x ∈ {x | 1 ≤ κ.rnDerivAux (κ + η) a x} → ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x) = 0 x

Proof state:
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ (((κ + η).withDensity fun a x => ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x)) a)
      {x | 1 ≤ κ.rnDerivAux (κ + η) a x} =
    0

Tactic:
rw [Kernel.withDensity_apply', lintegral_eq_zero_iff, EventuallyEq, ae_restrict_iff]

Result:
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ ∀ᵐ (x : γ) ∂(κ + η) a, x ∈ {x | 1 ≤ κ.rnDerivAux (κ + η) a x} → ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x) = 0 x

α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ MeasurableSet {x | ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x) = 0 x}

α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ Measurable fun b => ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a b)

case hf
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ Measurable (Function.uncurry fun a x => ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x))

Proof state:
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ Measurable fun x => ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x)

Tactic:
fun_prop

Result:
no goals

Proof state:
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ Measurable fun b => ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a b)

Tactic:
fun_prop

Result:
no goals

Proof state:
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ (η a) (κ.mutuallySingularSetSlice η a) = 0

Tactic:
suffices withDensity (κ + η) (fun a x ↦ Real.toNNReal
    (1 - rnDerivAux κ (κ + η) a x)) a {x | 1 ≤ rnDerivAux κ (κ + η) a x} = 0 by
  rwa [withDensity_one_sub_rnDerivAux κ η] at this

Result:
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ (((κ + η).withDensity fun a x => ↑(1 - κ.rnDerivAux (κ + η) a x).toNNReal) a) {x | 1 ≤ κ.rnDerivAux (κ + η) a x} = 0

Proof state:
case hf
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
⊢ Measurable (Function.uncurry fun a x => ENNReal.ofReal (1 - κ.rnDerivAux (κ + η) a x))

Tactic:
fun_prop

Result:
no goals

Proof state:
α : Type u_1
γ : Type u_2
mα : MeasurableSpace α
mγ : MeasurableSpace γ
hαγ : MeasurableSpace.CountableOrCountablyGenerated α γ
κ η : Kernel α γ
inst✝¹ : IsFiniteKernel κ
inst✝ : IsFiniteKernel η
a : α
this :
  (((κ + η).withDensity fun a x => ↑(1 - κ.rnDerivAux (κ + η) a x).toNNReal) a) {x | 1 ≤ κ.rnDerivAux (κ + η) a x} = 0
⊢ (η a) (κ.mutuallySingularSetSlice η a) = 0

Tactic:
rwa [withDensity_one_sub_rnDerivAux κ η] at this

Result:
no goals