Long time Hurst regularity of fractional SDEs and their ergodic means

Fuente: arXiv
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Autores principales: Haress, El Mehdi, Richard, Alexandre
Formato: Preprint
Publicado: 2022
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author Haress, El Mehdi
Richard, Alexandre
author_facet Haress, El Mehdi
Richard, Alexandre
contents The fractional Brownian motion can be considered as a Gaussian field indexed by $(t,H)\in {\mathbb{R}_{+}\times (0,1)}$, where $H$ is the Hurst parameter. On compact time intervals, it is known to be almost surely jointly Hölder continuous in time and Lipschitz continuous in $H$. First, we extend this result to the whole time interval $\mathbb{R}_{+}$ and consider both simple and rectangular increments. Then we consider SDEs driven by fractional Brownian motion with contractive drift. The solutions and their ergodic means are proven to be almost surely Hölder continuous in $H$, uniformly in time. This result is used in a separate work for statistical applications. We also deduce a sensibility result of the invariant measure in $H$. The proofs are based on variance estimates of the increments of the fractional Brownian motion and fractional Ornstein-Uhlenbeck processes, multiparameter versions of the Garsia-Rodemich-Rumsey lemma and a combinatorial argument to estimate the expectation of a product of Gaussian variables.
format Preprint
id arxiv_https___arxiv_org_abs_2206_06648
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Long time Hurst regularity of fractional SDEs and their ergodic means
Haress, El Mehdi
Richard, Alexandre
Probability
60G22, 60H10, 37H10
The fractional Brownian motion can be considered as a Gaussian field indexed by $(t,H)\in {\mathbb{R}_{+}\times (0,1)}$, where $H$ is the Hurst parameter. On compact time intervals, it is known to be almost surely jointly Hölder continuous in time and Lipschitz continuous in $H$. First, we extend this result to the whole time interval $\mathbb{R}_{+}$ and consider both simple and rectangular increments. Then we consider SDEs driven by fractional Brownian motion with contractive drift. The solutions and their ergodic means are proven to be almost surely Hölder continuous in $H$, uniformly in time. This result is used in a separate work for statistical applications. We also deduce a sensibility result of the invariant measure in $H$. The proofs are based on variance estimates of the increments of the fractional Brownian motion and fractional Ornstein-Uhlenbeck processes, multiparameter versions of the Garsia-Rodemich-Rumsey lemma and a combinatorial argument to estimate the expectation of a product of Gaussian variables.
title Long time Hurst regularity of fractional SDEs and their ergodic means
topic Probability
60G22, 60H10, 37H10
url https://arxiv.org/abs/2206.06648