Non-Markovianity of $2K-B$ and a degeneration

Fuente: arXiv
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Autores principales: Chu, Yang, Zhang, Lingfu
Formato: Preprint
Publicado: 2024
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author Chu, Yang
Zhang, Lingfu
author_facet Chu, Yang
Zhang, Lingfu
contents We study the process of $2K-B$, where $B$ is a standard one-dimensional Brownian motion and $K$ is its concave majorant. In light of Pitman's $2M-B$ theorem, it was recently conjectured by Ouaki and Pitman \cite{OP} that $2K-B$ has the law of the BES(5) process. The two processes share properties such as Brownian scaling, time inversion and quadratic variation, and the same one point distribution and infinitesimal generator, among many other evidences; and it remains to prove that $2K-B$ is Markovian. However, we show that this conjecture is false. To better understand the similarity between these two processes, we study a degeneration of $2K-B$. We show it is a mixture of BES(3), and get other properties including multiple points distribution, infinitesimal generator, and path decomposition at future infimum. We also further investigate the Markovian structure and the filtrations of $2K-B, B$ and $K$.
format Preprint
id arxiv_https___arxiv_org_abs_2410_04051
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Non-Markovianity of $2K-B$ and a degeneration
Chu, Yang
Zhang, Lingfu
Probability
We study the process of $2K-B$, where $B$ is a standard one-dimensional Brownian motion and $K$ is its concave majorant. In light of Pitman's $2M-B$ theorem, it was recently conjectured by Ouaki and Pitman \cite{OP} that $2K-B$ has the law of the BES(5) process. The two processes share properties such as Brownian scaling, time inversion and quadratic variation, and the same one point distribution and infinitesimal generator, among many other evidences; and it remains to prove that $2K-B$ is Markovian. However, we show that this conjecture is false. To better understand the similarity between these two processes, we study a degeneration of $2K-B$. We show it is a mixture of BES(3), and get other properties including multiple points distribution, infinitesimal generator, and path decomposition at future infimum. We also further investigate the Markovian structure and the filtrations of $2K-B, B$ and $K$.
title Non-Markovianity of $2K-B$ and a degeneration
topic Probability
url https://arxiv.org/abs/2410.04051