Documentation

BrownianMotion.StochasticIntegral.ClassD

Locally integrable, class D, class DL #

@[simp]
theorem WithTop.untopA_coe {α : Type u_1} [Nonempty α] {σ : α} :
(↑σ).untopA = σ

Helper Lemma

def ProbabilityTheory.HasStronglyMeasurableSupProcess {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} [LinearOrder ι] [MeasurableSpace ι] (X : ιΩE) :

The condition that the running supremum process (t, ω) ↦ sup_{s ≤ t} ‖X s ω‖ is strongly measurable as a function on the product.

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    def ProbabilityTheory.HasIntegrableSup {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} [LinearOrder ι] [MeasurableSpace ι] (X : ιΩE) (P : MeasureTheory.Measure Ω := by volume_tac) :

    A stochastic process has integrable supremum if the function (t, ω) ↦ sup_{s ≤ t} ‖X s ω‖ is strongly measurable and if for all t, the random variable ω ↦ sup_{s ≤ t} ‖X s ω‖ is integrable.

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      def ProbabilityTheory.HasLocallyIntegrableSup {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} [LinearOrder ι] [OrderBot ι] [TopologicalSpace ι] [OrderTopology ι] [MeasurableSpace ι] (X : ιΩE) (𝓕 : MeasureTheory.Filtration ι ) (P : MeasureTheory.Measure Ω := by volume_tac) :

      A stochastic process has locally integrable supremum if it satisfies locally the property that for all t, the random variable ω ↦ sup_{s ≤ t} ‖X s ω‖ is integrable.

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        structure ProbabilityTheory.ClassD {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} [Preorder ι] [Nonempty ι] [MeasurableSpace ι] (X : ιΩE) (𝓕 : MeasureTheory.Filtration ι ) (P : MeasureTheory.Measure Ω) :

        A stochastic process $(X_t)$ is of class D (or in the Doob-Meyer class) if it is adapted and the set $\{X_\tau \mid \tau \text{ is a finite stopping time}\}$ is uniformly integrable.

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          structure ProbabilityTheory.ClassDL {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} [Preorder ι] [Nonempty ι] [MeasurableSpace ι] (X : ιΩE) (𝓕 : MeasureTheory.Filtration ι ) (P : MeasureTheory.Measure Ω) :

          A stochastic process $(X_t)$ is of class DL if it is adapted and for all $t$, the set $\{X_\tau \mid \tau \text{ is a stopping time with } \tau \le t\}$ is uniformly integrable.

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            theorem ProbabilityTheory.ClassD.classDL {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} {P : MeasureTheory.Measure Ω} [Preorder ι] [Nonempty ι] [MeasurableSpace ι] {𝓕 : MeasureTheory.Filtration ι } {X : ιΩE} (hX : ClassD X 𝓕 P) :
            ClassDL X 𝓕 P
            theorem ProbabilityTheory.classD_of_uniformIntegrable_bounded_stoppingTime {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} {P : MeasureTheory.Measure Ω} [LinearOrder ι] [TopologicalSpace ι] [OrderTopology ι] [OrderBot ι] [MeasurableSpace ι] [SecondCountableTopology ι] {𝓕 : MeasureTheory.Filtration ι } {X : ιΩE} (hX : MeasureTheory.UniformIntegrable (fun (T : {T : ΩWithTop ι | MeasureTheory.IsStoppingTime 𝓕 T ∃ (t : ι), ∀ (ω : Ω), T ω t}) => MeasureTheory.stoppedValue X T) 1 P) (hm : MeasureTheory.ProgMeasurable 𝓕 X) :
            ClassD X 𝓕 P

            If {stoppedValue X T : T is a bounded stopping time} is uniformly integrable, then X is of class D.

            theorem MeasureTheory.Submartingale.classDL {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} {P : Measure Ω} {X : ιΩE} [LinearOrder ι] {𝓕 : Filtration ι } [TopologicalSpace ι] [OrderTopology ι] [OrderBot ι] [MeasurableSpace ι] [SecondCountableTopology ι] [NormedSpace E] [CompleteSpace E] [TopologicalSpace.PseudoMetrizableSpace ι] [BorelSpace ι] [Lattice E] [HasSolidNorm E] [IsOrderedAddMonoid E] [IsOrderedModule E] [IsFiniteMeasure P] (hX1 : Submartingale X 𝓕 P) (hX2 : ∀ (ω : Ω), Function.RightContinuous fun (x : ι) => X x ω) (hX3 : 0 X) :
            theorem MeasureTheory.Submartingale.uniformIntegrable_bounded_stoppingTime {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} {P : Measure Ω} {X : ιΩE} [LinearOrder ι] {𝓕 : Filtration ι } [TopologicalSpace ι] [OrderTopology ι] [OrderBot ι] [MeasurableSpace ι] [SecondCountableTopology ι] [NormedSpace E] [CompleteSpace E] [TopologicalSpace.PseudoMetrizableSpace ι] [BorelSpace ι] [Lattice E] [HasSolidNorm E] [IsOrderedAddMonoid E] [IsOrderedModule E] [IsFiniteMeasure P] (hX1 : Submartingale X 𝓕 P) (hX2 : ∀ (ω : Ω), Function.RightContinuous fun (x : ι) => X x ω) (hX3 : 0 X) (hX4 : UniformIntegrable X 1 P) :
            UniformIntegrable (fun (T : {T : ΩWithTop ι | IsStoppingTime 𝓕 T ∃ (t : ι), ∀ (ω : Ω), T ω t}) => stoppedValue X T) 1 P
            theorem MeasureTheory.Martingale.classDL {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} {P : Measure Ω} {X : ιΩE} [LinearOrder ι] {𝓕 : Filtration ι } [TopologicalSpace ι] [OrderTopology ι] [OrderBot ι] [MeasurableSpace ι] [SecondCountableTopology ι] [NormedSpace E] [CompleteSpace E] [IsFiniteMeasure P] [TopologicalSpace.PseudoMetrizableSpace ι] [BorelSpace ι] (hX1 : Martingale X 𝓕 P) (hX2 : ∀ (ω : Ω), Function.RightContinuous fun (x : ι) => X x ω) :
            theorem MeasureTheory.Martingale.classD_iff_uniformIntegrable {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} {P : Measure Ω} {X : ιΩE} [LinearOrder ι] {𝓕 : Filtration ι } [TopologicalSpace ι] [OrderTopology ι] [OrderBot ι] [MeasurableSpace ι] [SecondCountableTopology ι] [NormedSpace E] [CompleteSpace E] (hX1 : Martingale X 𝓕 P) (hX2 : ∀ (ω : Ω), Function.RightContinuous fun (x : ι) => X x ω) :
            theorem MeasureTheory.Integrable.classDL {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} {P : Measure Ω} {X : ιΩE} [LinearOrder ι] {𝓕 : Filtration ι } [Nonempty ι] [MeasurableSpace ι] (hX : ∀ (t : ι), Integrable (fun (ω : Ω) => ⨆ (s : ι), ⨆ (_ : s t), X t ω‖ₑ) P) :
            theorem ProbabilityTheory.HasLocallyIntegrableSup.locally_classDL {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} {P : MeasureTheory.Measure Ω} {X : ιΩE} [LinearOrder ι] {𝓕 : MeasureTheory.Filtration ι } [OrderBot ι] [TopologicalSpace ι] [OrderTopology ι] [MeasurableSpace ι] (hX1 : HasLocallyIntegrableSup X 𝓕 P) (hX2 : MeasureTheory.Adapted 𝓕 X) (h𝓕 : 𝓕.IsRightContinuous) :
            Locally (fun (x : ιΩE) => ClassDL x 𝓕 P) 𝓕 X P
            theorem ProbabilityTheory.ClassDL.classD {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} {P : MeasureTheory.Measure Ω} {X : ιΩE} [Preorder ι] {𝓕 : MeasureTheory.Filtration ι } [OrderTop ι] [MeasurableSpace ι] (hX : ClassDL X 𝓕 P) :
            ClassD X 𝓕 P
            theorem ProbabilityTheory.ClassDL.locally_classD {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} {P : MeasureTheory.Measure Ω} {X : ιΩE} [LinearOrder ι] {𝓕 : MeasureTheory.Filtration ι } [OrderBot ι] [TopologicalSpace ι] [SecondCountableTopology ι] [MeasurableSpace ι] [BorelSpace ι] [TopologicalSpace.PseudoMetrizableSpace ι] [OrderTopology ι] (hX : ClassDL X 𝓕 P) :
            Locally (fun (x : ιΩE) => ClassD x 𝓕 P) 𝓕 X P
            theorem ProbabilityTheory.locally_classD_of_locally_classDL {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} {P : MeasureTheory.Measure Ω} {ι : Type u_4} [ConditionallyCompleteLinearOrderBot ι] [TopologicalSpace ι] [OrderTopology ι] [DenselyOrdered ι] [SecondCountableTopology ι] [NoMaxOrder ι] [MeasurableSpace ι] [BorelSpace ι] [TopologicalSpace.PseudoMetrizableSpace ι] {𝓕 : MeasureTheory.Filtration ι } {X : ιΩE} [MeasureTheory.IsFiniteMeasure P] (hX : Locally (fun (x : ιΩE) => ClassDL x 𝓕 P) 𝓕 X P) (h𝓕 : 𝓕.IsRightContinuous) :
            Locally (fun (x : ιΩE) => ClassD x 𝓕 P) 𝓕 X P
            theorem ProbabilityTheory.isLocalizingSequence_hittingAfter_Ici {Ω : Type u_2} { : MeasurableSpace Ω} {P : MeasureTheory.Measure Ω} {ι : Type u_4} [PartialOrder ι] [TopologicalSpace ι] [OrderTopology ι] [FirstCountableTopology ι] [InfSet ι] [Bot ι] [CompactIccSpace ι] (𝓕 : MeasureTheory.Filtration ι ) (τ : ΩWithTop ι) {X : ιΩ} (hX1 : MeasureTheory.Adapted 𝓕 X) (hX2 : ∀ (ω : Ω), Function.RightContinuous fun (x : ι) => X x ω) (h𝓕 : 𝓕.IsRightContinuous) :
            theorem ProbabilityTheory.sup_stoppedProcess_hittingAfter_Ici_le {Ω : Type u_2} {E : Type u_4} [NormedAddCommGroup E] {ι : Type u_5} [ConditionallyCompleteLinearOrderBot ι] {X : ιΩE} (t : ι) (K : ) (hK : 0 K) (ω : Ω) :
            ⨆ (s : ι), ⨆ (_ : s t), MeasureTheory.stoppedProcess X (MeasureTheory.hittingAfter (fun (t : ι) (ω : Ω) => X t ω) (Set.Ici K) ) s ω K + {ω : Ω | MeasureTheory.hittingAfter (fun (t : ι) (ω : Ω) => X t ω) (Set.Ici K) ω t}.indicator (fun (ω : Ω) => MeasureTheory.stoppedValue X (MeasureTheory.hittingAfter (fun (t : ι) (ω : Ω) => X t ω) (Set.Ici K) ) ω) ω
            theorem ProbabilityTheory.ClassDL.hasLocallyIntegrableSup {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} {P : MeasureTheory.Measure Ω} {X : ιΩE} [LinearOrder ι] {𝓕 : MeasureTheory.Filtration ι } [TopologicalSpace ι] [OrderTopology ι] [FirstCountableTopology ι] [InfSet ι] [CompactIccSpace ι] [OrderBot ι] [MeasurableSpace ι] (hX1 : ∀ (ω : Ω), IsCadlag fun (x : ι) => X x ω) (hX2 : ClassDL X 𝓕 P) (h𝓕 : 𝓕.IsRightContinuous) :
            theorem ProbabilityTheory.hasLocallyIntegrableSup_of_locally_classDL {ι : Type u_1} {Ω : Type u_2} {E : Type u_3} [NormedAddCommGroup E] { : MeasurableSpace Ω} {P : MeasureTheory.Measure Ω} {X : ιΩE} [ConditionallyCompleteLinearOrderBot ι] [TopologicalSpace ι] [OrderTopology ι] [MeasurableSpace ι] [SecondCountableTopology ι] [DenselyOrdered ι] [NoMaxOrder ι] [BorelSpace ι] [TopologicalSpace.PseudoMetrizableSpace ι] [MeasureTheory.IsFiniteMeasure P] {𝓕 : MeasureTheory.Filtration ι } {h𝓕 : 𝓕.IsRightContinuous} (hX1 : Locally (fun (X : ιΩE) => ∀ (ω : Ω), IsCadlag fun (x : ι) => X x ω) 𝓕 X P) (hX2 : Locally (fun (x : ιΩE) => ClassDL x 𝓕 P) 𝓕 X P) :