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)
a b : ℕ
hb : b ≥ a + 1
⊢ (Kernel.id.map id ×ₖ (traj κ a).map ((fun x i ↦ x ⟨↑i, ⋯⟩) ∘ (Set.Ioi a).domRestrict)).map (_root_.IicProdIoc a b) =
    partialTraj κ a b

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)
a b : ℕ
hb : b ≥ a + 1
⊢ Measurable (Set.Ioi a).domRestrict

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)
a b : ℕ
hb : b ≥ a + 1
⊢ Measurable fun x i ↦ x ⟨↑i, ⋯⟩

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)
a b : ℕ
hb : b ≥ a + 1
⊢ MeasurableSpace ((i : ↥(Ioc a b)) → X ↑i)

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)
a b : ℕ
hb : b ≥ a + 1
⊢ Measurable id

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)
a b : ℕ
hb : b ≥ a + 1
⊢ Measurable fun x i ↦ x ⟨↑i, ⋯⟩

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)
a b : ℕ
hb : b ≥ a + 1
⊢ MeasurableSpace ((i : ↥(Iic a)) → X ↑i)

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)
a b : ℕ
hb : b ≥ a + 1
⊢ Measurable (Prod.map id fun x i ↦ x ⟨↑i, ⋯⟩)

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)
a b : ℕ
hb : b ≥ a + 1
⊢ Measurable (_root_.IicProdIoc a b)

Tactic:
· conv_lhs => enter [1, 2, 2]; change (Ioc a b).restrict
      rw [← restrict₂_comp_restrict Ioc_subset_Iic_self, ← frestrictLe, map_comp_right,
        traj_map_frestrictLe, map_id, ← partialTraj_eq_prod]
      all_goals fun_prop

Goal state after:
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)
a b : ℕ
hb : b ≥ a + 1
⊢ Measurable (Set.Ioi a).domRestrict

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)
a b : ℕ
hb : b ≥ a + 1
⊢ Measurable fun x i ↦ x ⟨↑i, ⋯⟩

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)
a b : ℕ
hb : b ≥ a + 1
⊢ Measurable id

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)
a b : ℕ
hb : b ≥ a + 1
⊢ Measurable fun x i ↦ x ⟨↑i, ⋯⟩

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)
a b : ℕ
hb : b ≥ a + 1
⊢ Measurable (Prod.map id fun x i ↦ 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)
a b : ℕ
hb : b ≥ a + 1
⊢ Measurable (_root_.IicProdIoc a b)