Module: Mathlib.Probability.Kernel.IonescuTulcea.Traj

Goal state before:
pp: X : ℕ → Type u_1
inst✝¹ : (n : ℕ) → MeasurableSpace (X n)
κ : (n : ℕ) → Kernel ((i : ↥(Iic n)) → X ↑i) (X (n + 1))
inst✝ : ∀ (n : ℕ), IsMarkovKernel (κ n)
n : ℕ
x : (i : ↥(Iic n)) → X ↑i
this : (fun x_1 ↦ updateFinset x_1 (Iic n) x) = ⇑(IicProdIoi n) ∘ Prod.mk x ∘ (Set.Ioi n).domRestrict
⊢ Measure.map (⇑(IicProdIoi n) ∘ Prod.mk x) (Measure.map (Set.Ioi n).domRestrict ((traj κ n) x)) =
    ((Kernel.id ×ₖ (traj κ n).map (Set.Ioi n).domRestrict).map ⇑(IicProdIoi n)) x

pp: case hg
X : ℕ → Type u_1
inst✝¹ : (n : ℕ) → MeasurableSpace (X n)
κ : (n : ℕ) → Kernel ((i : ↥(Iic n)) → X ↑i) (X (n + 1))
inst✝ : ∀ (n : ℕ), IsMarkovKernel (κ n)
n : ℕ
x : (i : ↥(Iic n)) → X ↑i
this : (fun x_1 ↦ updateFinset x_1 (Iic n) x) = ⇑(IicProdIoi n) ∘ Prod.mk x ∘ (Set.Ioi n).domRestrict
⊢ Measurable (⇑(IicProdIoi n) ∘ Prod.mk x)

pp: case hf
X : ℕ → Type u_1
inst✝¹ : (n : ℕ) → MeasurableSpace (X n)
κ : (n : ℕ) → Kernel ((i : ↥(Iic n)) → X ↑i) (X (n + 1))
inst✝ : ∀ (n : ℕ), IsMarkovKernel (κ n)
n : ℕ
x : (i : ↥(Iic n)) → X ↑i
this : (fun x_1 ↦ updateFinset x_1 (Iic n) x) = ⇑(IicProdIoi n) ∘ Prod.mk x ∘ (Set.Ioi n).domRestrict
⊢ Measurable (Set.Ioi n).domRestrict

pp: X : ℕ → Type u_1
inst✝¹ : (n : ℕ) → MeasurableSpace (X n)
κ : (n : ℕ) → Kernel ((i : ↥(Iic n)) → X ↑i) (X (n + 1))
inst✝ : ∀ (n : ℕ), IsMarkovKernel (κ n)
n : ℕ
x : (i : ↥(Iic n)) → X ↑i
this : (fun x_1 ↦ updateFinset x_1 (Iic n) x) = ⇑(IicProdIoi n) ∘ Prod.mk x ∘ (Set.Ioi n).domRestrict
⊢ MeasurableSpace ((i : ↑(Set.Ioi n)) → X ↑i)

Tactic:
← Measure.map_map,

Goal state after:
X : ℕ → Type u_1
inst✝¹ : (n : ℕ) → MeasurableSpace (X n)
κ : (n : ℕ) → Kernel ((i : ↥(Iic n)) → X ↑i) (X (n + 1))
inst✝ : ∀ (n : ℕ), IsMarkovKernel (κ n)
n : ℕ
x : (i : ↥(Iic n)) → X ↑i
this : (fun x_1 ↦ updateFinset x_1 (Iic n) x) = ⇑(IicProdIoi n) ∘ Prod.mk x ∘ (Set.Ioi n).domRestrict
⊢ Measure.map (⇑(IicProdIoi n)) (Measure.map (Prod.mk x) (Measure.map (Set.Ioi n).domRestrict ((traj κ n) x))) =
    ((Kernel.id ×ₖ (traj κ n).map (Set.Ioi n).domRestrict).map ⇑(IicProdIoi n)) x

case hg
X : ℕ → Type u_1
inst✝¹ : (n : ℕ) → MeasurableSpace (X n)
κ : (n : ℕ) → Kernel ((i : ↥(Iic n)) → X ↑i) (X (n + 1))
inst✝ : ∀ (n : ℕ), IsMarkovKernel (κ n)
n : ℕ
x : (i : ↥(Iic n)) → X ↑i
this : (fun x_1 ↦ updateFinset x_1 (Iic n) x) = ⇑(IicProdIoi n) ∘ Prod.mk x ∘ (Set.Ioi n).domRestrict
⊢ Measurable ⇑(IicProdIoi n)

case hf
X : ℕ → Type u_1
inst✝¹ : (n : ℕ) → MeasurableSpace (X n)
κ : (n : ℕ) → Kernel ((i : ↥(Iic n)) → X ↑i) (X (n + 1))
inst✝ : ∀ (n : ℕ), IsMarkovKernel (κ n)
n : ℕ
x : (i : ↥(Iic n)) → X ↑i
this : (fun x_1 ↦ updateFinset x_1 (Iic n) x) = ⇑(IicProdIoi n) ∘ Prod.mk x ∘ (Set.Ioi n).domRestrict
⊢ Measurable (Prod.mk x)

X : ℕ → Type u_1
inst✝¹ : (n : ℕ) → MeasurableSpace (X n)
κ : (n : ℕ) → Kernel ((i : ↥(Iic n)) → X ↑i) (X (n + 1))
inst✝ : ∀ (n : ℕ), IsMarkovKernel (κ n)
n : ℕ
x : (i : ↥(Iic n)) → X ↑i
this : (fun x_1 ↦ updateFinset x_1 (Iic n) x) = ⇑(IicProdIoi n) ∘ Prod.mk x ∘ (Set.Ioi n).domRestrict
⊢ MeasurableSpace ((i : ↑(Set.Ioi n)) → X ↑i)

X : ℕ → Type u_1
inst✝¹ : (n : ℕ) → MeasurableSpace (X n)
κ : (n : ℕ) → Kernel ((i : ↥(Iic n)) → X ↑i) (X (n + 1))
inst✝ : ∀ (n : ℕ), IsMarkovKernel (κ n)
n : ℕ
x : (i : ↥(Iic n)) → X ↑i
this : (fun x_1 ↦ updateFinset x_1 (Iic n) x) = ⇑(IicProdIoi n) ∘ Prod.mk x ∘ (Set.Ioi n).domRestrict
⊢ MeasurableSpace (((i : ↥(Iic n)) → X ↑i) × ((i : ↑(Set.Ioi n)) → X ↑i))

case hg
X : ℕ → Type u_1
inst✝¹ : (n : ℕ) → MeasurableSpace (X n)
κ : (n : ℕ) → Kernel ((i : ↥(Iic n)) → X ↑i) (X (n + 1))
inst✝ : ∀ (n : ℕ), IsMarkovKernel (κ n)
n : ℕ
x : (i : ↥(Iic n)) → X ↑i
this : (fun x_1 ↦ updateFinset x_1 (Iic n) x) = ⇑(IicProdIoi n) ∘ Prod.mk x ∘ (Set.Ioi n).domRestrict
⊢ Measurable (⇑(IicProdIoi n) ∘ Prod.mk x)

case hf
X : ℕ → Type u_1
inst✝¹ : (n : ℕ) → MeasurableSpace (X n)
κ : (n : ℕ) → Kernel ((i : ↥(Iic n)) → X ↑i) (X (n + 1))
inst✝ : ∀ (n : ℕ), IsMarkovKernel (κ n)
n : ℕ
x : (i : ↥(Iic n)) → X ↑i
this : (fun x_1 ↦ updateFinset x_1 (Iic n) x) = ⇑(IicProdIoi n) ∘ Prod.mk x ∘ (Set.Ioi n).domRestrict
⊢ Measurable (Set.Ioi n).domRestrict