Abstract

This paper is concerned with various aspects of the Slepian process $(B_{t+1} - B_t, t \ge 0)$ derived from a one-dimensional Brownian motion $(B_t, t \ge 0 )$. In particular, we offer an analysis of the local structure of the Slepian zero set $\{t : B_{t+1} = B_t \}$, including a path decomposition of the Slepian process for $0 \le t \le 1$. We also establish the existence of a random time $T$ such that $T$ falls in the the Slepian zero set almost surely and the process $(B_{T+u} - B_T, 0 \le u \le 1)$ is standard Brownian bridge.

Highlights

  • Introduction and main resultIn a recent work [66], we were interested in continuous paths of length 1 in Brownian motion (Bt; t ≥ 0)

  • We proved that Brownian meander m and the three-dimensional Bessel process R can be embedded into Brownian motion by a random translation of origin in spacetime, while it is not the case for either normalized Brownian excursion e or reflected Brownian bridge |b0|

  • Can we find a random time T ≥ 0 such that (BT +u − BT ; 0 ≤ u ≤ 1) has the same distribution as standard Brownian bridge (b0u; 0 ≤ u ≤ 1)?

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Summary

Introduction and main result

In a recent work [66], we were interested in continuous paths of length 1 in Brownian motion (Bt; t ≥ 0). In terms of the moving-window process, it is equivalent to find a random time T ≥ 0 such that XT has the same distribution as Brownian bridge b0. While the paper was under review, we learned from Hermann Thorisson [79] an explicit embedding of Brownian bridge into Brownian motion by a spacetime shift His argument is mainly from Last et al [51], that is to construct allocation rules balancing stationary diffuse random measures on the real line. They were able to characterize unbiased shifts of Brownian motion, those are random times T ∈ R such that (BT +u − BT ; u ≥ 0) is a two-sided Brownian motion, independent of BT Though it appears to be easier, Thorisson’s constructive proof relies on a deep and powerful theory. The constructive proof in Subsection 5.4 is due to Hermann Thorisson

Random walk approximation
The Slepian process
The Slepian zero set and path decomposition
Local absolute continuity between Slepian zeros and Brownian zeros
A Palm-Itô measure related to Slepian zeros
Brownian bridge embedded in Brownian motion
Local times of X and its Palm measure
Brownian bridge in two-sided Brownian motion
From two-sided embedding to one-sided embedding
An explicit embedding of Brownian bridge into Brownian motion
An allocation rule τ is said to balance two random measures ξ and η if
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