Module: Mathlib.Probability.Kernel.Disintegration.Density

Goal state before:
pp: α : Type u_1
β : Type u_2
γ : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
mγ : MeasurableSpace γ
inst✝¹ : CountablyGenerated γ
κ : Kernel α (γ × β)
ν : Kernel α γ
hκν : κ.fst ≤ ν
inst✝ : IsFiniteKernel ν
n : ℕ
a : α
s : Set β
hs : MeasurableSet s
this : IsFiniteKernel κ
S : Finset (Set γ)
hS_subset : ↑S ⊆ countablePartition γ n
hA : MeasurableSet (⋃₀ ↑S)
h_disj : Pairwise (Disjoint on fun i ↦ ↑i)
⊢ ∫ (x : γ) in ⋃ i, ↑i, κ.densityProcess ν n a x s ∂ν a = (κ a).real ((⋃ i, ↑i) ×ˢ s)

Tactic:
rw [integral_iUnion, iUnion_prod_const, measureReal_def, measure_iUnion,
      ENNReal.tsum_toReal_eq (fun _ ↦ measure_ne_top _ _)]

Goal state after:
α : Type u_1
β : Type u_2
γ : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
mγ : MeasurableSpace γ
inst✝¹ : CountablyGenerated γ
κ : Kernel α (γ × β)
ν : Kernel α γ
hκν : κ.fst ≤ ν
inst✝ : IsFiniteKernel ν
n : ℕ
a : α
s : Set β
hs : MeasurableSet s
this : IsFiniteKernel κ
S : Finset (Set γ)
hS_subset : ↑S ⊆ countablePartition γ n
hA : MeasurableSet (⋃₀ ↑S)
h_disj : Pairwise (Disjoint on fun i ↦ ↑i)
⊢ ∑' (n_1 : ↑↑S), ∫ (x : γ) in ↑n_1, κ.densityProcess ν n a x s ∂ν a = ∑' (a_1 : ↑↑S), ((κ a) (↑a_1 ×ˢ s)).toReal

case hn
α : Type u_1
β : Type u_2
γ : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
mγ : MeasurableSpace γ
inst✝¹ : CountablyGenerated γ
κ : Kernel α (γ × β)
ν : Kernel α γ
hκν : κ.fst ≤ ν
inst✝ : IsFiniteKernel ν
n : ℕ
a : α
s : Set β
hs : MeasurableSet s
this : IsFiniteKernel κ
S : Finset (Set γ)
hS_subset : ↑S ⊆ countablePartition γ n
hA : MeasurableSet (⋃₀ ↑S)
h_disj : Pairwise (Disjoint on fun i ↦ ↑i)
⊢ Pairwise (Disjoint on fun i ↦ ↑i ×ˢ s)

case h
α : Type u_1
β : Type u_2
γ : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
mγ : MeasurableSpace γ
inst✝¹ : CountablyGenerated γ
κ : Kernel α (γ × β)
ν : Kernel α γ
hκν : κ.fst ≤ ν
inst✝ : IsFiniteKernel ν
n : ℕ
a : α
s : Set β
hs : MeasurableSet s
this : IsFiniteKernel κ
S : Finset (Set γ)
hS_subset : ↑S ⊆ countablePartition γ n
hA : MeasurableSet (⋃₀ ↑S)
h_disj : Pairwise (Disjoint on fun i ↦ ↑i)
⊢ ∀ (i : ↑↑S), MeasurableSet (↑i ×ˢ s)

case hm
α : Type u_1
β : Type u_2
γ : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
mγ : MeasurableSpace γ
inst✝¹ : CountablyGenerated γ
κ : Kernel α (γ × β)
ν : Kernel α γ
hκν : κ.fst ≤ ν
inst✝ : IsFiniteKernel ν
n : ℕ
a : α
s : Set β
hs : MeasurableSet s
this : IsFiniteKernel κ
S : Finset (Set γ)
hS_subset : ↑S ⊆ countablePartition γ n
hA : MeasurableSet (⋃₀ ↑S)
h_disj : Pairwise (Disjoint on fun i ↦ ↑i)
⊢ ∀ (i : ↑↑S), MeasurableSet ↑i

case hd
α : Type u_1
β : Type u_2
γ : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
mγ : MeasurableSpace γ
inst✝¹ : CountablyGenerated γ
κ : Kernel α (γ × β)
ν : Kernel α γ
hκν : κ.fst ≤ ν
inst✝ : IsFiniteKernel ν
n : ℕ
a : α
s : Set β
hs : MeasurableSet s
this : IsFiniteKernel κ
S : Finset (Set γ)
hS_subset : ↑S ⊆ countablePartition γ n
hA : MeasurableSet (⋃₀ ↑S)
h_disj : Pairwise (Disjoint on fun i ↦ ↑i)
⊢ Pairwise (Disjoint on Subtype.val)

case hfi
α : Type u_1
β : Type u_2
γ : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
mγ : MeasurableSpace γ
inst✝¹ : CountablyGenerated γ
κ : Kernel α (γ × β)
ν : Kernel α γ
hκν : κ.fst ≤ ν
inst✝ : IsFiniteKernel ν
n : ℕ
a : α
s : Set β
hs : MeasurableSet s
this : IsFiniteKernel κ
S : Finset (Set γ)
hS_subset : ↑S ⊆ countablePartition γ n
hA : MeasurableSet (⋃₀ ↑S)
h_disj : Pairwise (Disjoint on fun i ↦ ↑i)
⊢ IntegrableOn (fun x ↦ κ.densityProcess ν n a x s) (⋃ i, ↑i) (ν a)