Theorem: ProbabilityTheory.Kernel.compProdFun_tsum_right
File: Mathlib/Probability/Kernel/Composition.lean

Proof steps:
state_before: α : Type u_1
β : Type u_2
ι : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
γ : Type u_4
mγ : MeasurableSpace γ
s : Set (β × γ)
κ : Kernel α β
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
hs : MeasurableSet s
⊢ κ.compProdFun η a s = ∑' (n : ℕ), κ.compProdFun (η.seq n) a s
state_after: α : Type u_1
β : Type u_2
ι : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
γ : Type u_4
mγ : MeasurableSpace γ
s : Set (β × γ)
κ : Kernel α β
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
hs : MeasurableSet s
⊢ ∫⁻ (b : β), (Measure.sum fun n => (η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a =
    ∑' (n : ℕ), ∫⁻ (b : β), ((η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a
tactic: simp_rw [compProdFun, (measure_sum_seq η _).symm]
state_before: α : Type u_1
β : Type u_2
ι : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
γ : Type u_4
mγ : MeasurableSpace γ
s : Set (β × γ)
κ : Kernel α β
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
hs : MeasurableSet s
⊢ ∫⁻ (b : β), (Measure.sum fun n => (η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a =
    ∑' (n : ℕ), ∫⁻ (b : β), ((η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a
state_after: α : Type u_1
β : Type u_2
ι : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
γ : Type u_4
mγ : MeasurableSpace γ
s : Set (β × γ)
κ : Kernel α β
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
hs : MeasurableSet s
this :
  ∫⁻ (b : β), (Measure.sum fun n => (η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a =
    ∫⁻ (b : β), ∑' (n : ℕ), ((η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a
⊢ ∫⁻ (b : β), (Measure.sum fun n => (η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a =
    ∑' (n : ℕ), ∫⁻ (b : β), ((η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a
tactic: have :
    ∫⁻ b, Measure.sum (fun n => seq η n (a, b)) {c : γ | (b, c) ∈ s} ∂κ a =
      ∫⁻ b, ∑' n, seq η n (a, b) {c : γ | (b, c) ∈ s} ∂κ a := by
    congr
    ext1 b
    rw [Measure.sum_apply]
    exact measurable_prod_mk_left hs
state_before: α : Type u_1
β : Type u_2
ι : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
γ : Type u_4
mγ : MeasurableSpace γ
s : Set (β × γ)
κ : Kernel α β
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
hs : MeasurableSet s
this :
  ∫⁻ (b : β), (Measure.sum fun n => (η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a =
    ∫⁻ (b : β), ∑' (n : ℕ), ((η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a
⊢ ∫⁻ (b : β), (Measure.sum fun n => (η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a =
    ∑' (n : ℕ), ∫⁻ (b : β), ((η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a
state_after: α : Type u_1
β : Type u_2
ι : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
γ : Type u_4
mγ : MeasurableSpace γ
s : Set (β × γ)
κ : Kernel α β
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
hs : MeasurableSet s
this :
  ∫⁻ (b : β), (Measure.sum fun n => (η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a =
    ∫⁻ (b : β), ∑' (n : ℕ), ((η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a
⊢ ∀ (i : ℕ), AEMeasurable (fun b => ((η.seq i) (a, b)) {c | (b, c) ∈ s}) (κ a)
tactic: rw [this, lintegral_tsum]
state_before: α : Type u_1
β : Type u_2
ι : Type u_3
mα : MeasurableSpace α
mβ : MeasurableSpace β
γ : Type u_4
mγ : MeasurableSpace γ
s : Set (β × γ)
κ : Kernel α β
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
hs : MeasurableSet s
this :
  ∫⁻ (b : β), (Measure.sum fun n => (η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a =
    ∫⁻ (b : β), ∑' (n : ℕ), ((η.seq n) (a, b)) {c | (b, c) ∈ s} ∂κ a
⊢ ∀ (i : ℕ), AEMeasurable (fun b => ((η.seq i) (a, b)) {c | (b, c) ∈ s}) (κ a)
state_after: no goals
tactic: exact fun n => ((measurable_kernel_prod_mk_left (κ := (seq η n))
    ((measurable_fst.snd.prod_mk measurable_snd) hs)).comp measurable_prod_mk_left).aemeasurable