Theorem: ProbabilityTheory.Kernel.ae_null_of_compProd_null
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
inst✝¹ : IsSFiniteKernel κ
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
h : ((κ ⊗ₖ η) a) s = 0
⊢ (fun b => (η (a, b)) (Prod.mk b ⁻¹' s)) =ᶠ[ae (κ a)] 0
state_after: case intro.intro.intro
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
inst✝¹ : IsSFiniteKernel κ
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
h : ((κ ⊗ₖ η) a) s = 0
t : Set (β × γ)
hst : s ⊆ t
mt : MeasurableSet t
ht : ((κ ⊗ₖ η) a) t = 0
⊢ (fun b => (η (a, b)) (Prod.mk b ⁻¹' s)) =ᶠ[ae (κ a)] 0
tactic: obtain ⟨t, hst, mt, ht⟩ := exists_measurable_superset_of_null h
state_before: case intro.intro.intro
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
inst✝¹ : IsSFiniteKernel κ
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
h : ((κ ⊗ₖ η) a) s = 0
t : Set (β × γ)
hst : s ⊆ t
mt : MeasurableSet t
ht : ((κ ⊗ₖ η) a) t = 0
⊢ (fun b => (η (a, b)) (Prod.mk b ⁻¹' s)) =ᶠ[ae (κ a)] 0
state_after: case intro.intro.intro
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
inst✝¹ : IsSFiniteKernel κ
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
h : ((κ ⊗ₖ η) a) s = 0
t : Set (β × γ)
hst : s ⊆ t
mt : MeasurableSet t
ht : (fun b => (η (a, b)) (Prod.mk b ⁻¹' t)) =ᶠ[ae (κ a)] 0
⊢ (fun b => (η (a, b)) (Prod.mk b ⁻¹' s)) =ᶠ[ae (κ a)] 0
tactic: simp_rw [compProd_null a mt] at ht
state_before: case intro.intro.intro
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
inst✝¹ : IsSFiniteKernel κ
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
h : ((κ ⊗ₖ η) a) s = 0
t : Set (β × γ)
hst : s ⊆ t
mt : MeasurableSet t
ht : (fun b => (η (a, b)) (Prod.mk b ⁻¹' t)) =ᶠ[ae (κ a)] 0
⊢ (fun b => (η (a, b)) (Prod.mk b ⁻¹' s)) =ᶠ[ae (κ a)] 0
state_after: case intro.intro.intro
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
inst✝¹ : IsSFiniteKernel κ
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
h : ((κ ⊗ₖ η) a) s = 0
t : Set (β × γ)
hst : s ⊆ t
mt : MeasurableSet t
ht : (fun b => (η (a, b)) (Prod.mk b ⁻¹' t)) =ᶠ[ae (κ a)] 0
⊢ (fun b => (η (a, b)) (Prod.mk b ⁻¹' s)) ≤ᶠ[ae (κ a)] 0 ∧ 0 ≤ᶠ[ae (κ a)] fun b => (η (a, b)) (Prod.mk b ⁻¹' s)
tactic: rw [Filter.eventuallyLE_antisymm_iff]
state_before: case intro.intro.intro
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
inst✝¹ : IsSFiniteKernel κ
η : Kernel (α × β) γ
inst✝ : IsSFiniteKernel η
a : α
h : ((κ ⊗ₖ η) a) s = 0
t : Set (β × γ)
hst : s ⊆ t
mt : MeasurableSet t
ht : (fun b => (η (a, b)) (Prod.mk b ⁻¹' t)) =ᶠ[ae (κ a)] 0
⊢ (fun b => (η (a, b)) (Prod.mk b ⁻¹' s)) ≤ᶠ[ae (κ a)] 0 ∧ 0 ≤ᶠ[ae (κ a)] fun b => (η (a, b)) (Prod.mk b ⁻¹' s)
state_after: no goals
tactic: exact
    ⟨Filter.EventuallyLE.trans_eq
        (Filter.eventually_of_forall fun x => (measure_mono (Set.preimage_mono hst) : _)) ht,
      Filter.eventually_of_forall fun x => zero_le _⟩