Finite-stopping strong Markov factorisation for continuous finite-dimensional rewards
ProvedAvramDividend.Classical.levy_finiteStopping_continuousCylinderReward_scalar_markovavram-classicalcylinder-rewardfinite-dimensionalstopping-timestrong-markov
The strong Markov factorisation for any finite stopping time holds for bounded continuous measurable rewards of finitely many future increments of a Lévy process, on a stopped-history event. The measurable truncated reward premise is explicit and can be discharged separately from càdlàg path measurability.
Preamble
import Mathlib.Probability.Process.Stopping import Mathlib.Topology.Constructions import Mathlib.MeasureTheory.Constructions.Pi import Definitions.Def_AvramDividend_Classical_SpectrallyNegativeLevy import Theorems.Thm_AvramDividend_Classical_levy_finiteStopping_boundedReward_scalar_markov open MeasureTheory ProbabilityTheory Filter Set open scoped NNReal ENNReal open AvramDividend.Classical
Formal statement
theorem AvramDividend.Classical.levy_finiteStopping_continuousCylinderReward_scalar_markov
{Ω : Type*} [mΩ : MeasurableSpace Ω] {P : Measure Ω}
{𝓕 : Filtration ℝ≥0 mΩ}
(X : SpectrallyNegativeLevy P 𝓕)
(τ : Ω → ℝ≥0)
(hstop : IsStoppingTime 𝓕 (fun ω => (τ ω : WithTop ℝ≥0)))
(A : Set Ω)
(hA : ∀ s : ℝ≥0,
MeasurableSet[𝓕 s] (A ∩ {ω : Ω | τ ω ≤ s}))
(J : Finset ℝ≥0)
(h : (J → ℝ) → ℝ≥0∞)
(hh : Continuous h) (hhm : Measurable h)
(C : ℝ≥0∞) (hbound : ∀ z, h z ≤ C)
(hfin : (∫⁻ _ : Ω, C ∂P) ≠ ∞)
(hMeas : ∀ n : ℕ, Measurable (Set.indicator
(A ∩ {ω' : Ω | τ ω' ≤ (n : ℝ≥0)})
(fun ω' : Ω => h (fun j : J =>
X.X (τ ω' + (j : ℝ≥0)) ω' - X.X (τ ω') ω')))) :
(∫⁻ ω, Set.indicator A
(fun ω' : Ω => h (fun j : J =>
X.X (τ ω' + (j : ℝ≥0)) ω' - X.X (τ ω') ω')) ω ∂P) =
P A * (∫⁻ y, h (fun j : J => y (j : ℝ≥0))
∂(Measure.map
(fun ω : Ω => fun t : ℝ≥0 => X.X t ω) P)) := by
sorrySource
Specialises Proved finite-stopping bounded future-path reward formula to arbitrary finite coordinate sets. A finite-dimensional law bridge toward the whole stopped Lévy path factorisation 61930a38-11f1-449e-bbb6-67d59c6d5ca8 and barrier splitting 79978d61-9d1f-4b20-b8a5-114797a8e380.