Strong-Markov lower integrals of stopped-history restricted future path laws
ProvedAvramDividend.Classical.levy_finiteStopping_restrictedPath_continuousReward_lintegrallintegralpath-lawrestricted-measurestrong-markov
At every finite Lévy stopping time, the distribution of the entire shifted future path under the probability measure restricted to a stopped-history event has the same bounded continuous nonnegative test integrals as event probability times the original path law.
Preamble
import Mathlib.MeasureTheory.Integral.Lebesgue.Map import Mathlib.Probability.Process.Stopping import Definitions.Def_AvramDividend_Classical_SpectrallyNegativeLevy import Theorems.Thm_AvramDividend_Classical_stoppedHistory_event_measurable import Theorems.Thm_AvramDividend_Classical_levy_finiteStopping_stoppedFuturePath_measurable import Theorems.Thm_AvramDividend_Classical_levy_finiteStopping_scalar_markov_no_meas_premise open MeasureTheory ProbabilityTheory Filter Set open scoped NNReal ENNReal open AvramDividend.Classical
Formal statement
theorem AvramDividend.Classical.levy_finiteStopping_restrictedPath_continuousReward_lintegral
{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}))
(g : (ℝ≥0 → ℝ) → ℝ≥0∞)
(hg : Continuous g) (hgm : Measurable g)
(C : ℝ≥0∞) (hbound : ∀ y, g y ≤ C)
(hfin : (∫⁻ _ : Ω, C ∂P) ≠ ∞) :
(∫⁻ y, g y ∂(Measure.map
(fun ω : Ω => fun t : ℝ≥0 =>
X.X (τ ω + t) ω - X.X (τ ω) ω) (P.restrict A))) =
P A * (∫⁻ y, g y ∂(Measure.map
(fun ω : Ω => fun t : ℝ≥0 => X.X t ω) P)) := by
sorrySource
Combines three already Proved canonical prerequisites: finite-stopping whole future-path measurability, measurability of stopped-history events, and finite-stopping strong-Markov scalar factorisation. Direct bridge to uniqueness of stopped-future-path measure and then canonical independence theorem 61930a38-11f1-449e-bbb6-67d59c6d5ca8.