Fluctuation of ergodic averages and other stochastic processes

Fuente: arXiv
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Autores principales: Mondal, Sovanlal, Rosenblatt, Joe, Wierdl, Máté
Formato: Preprint
Publicado: 2024
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author Mondal, Sovanlal
Rosenblatt, Joe
Wierdl, Máté
author_facet Mondal, Sovanlal
Rosenblatt, Joe
Wierdl, Máté
contents For an ergodic map $T$ and a non-constant, real-valued $f \in L^1$, the ergodic averages $\mathbb{A}_N f(x) = \frac{1} {N} \sum_{n=1}^N f(T^n x)$ converge a.e., but the convergence is never monotone. Depending on particular properties of the function $f$, the averages $\mathbb{A}_N f(x)$ may or may not actually fluctuate around the mean value infinitely often a.e. We will prove that a.e. fluctuation around the mean is the generic behavior. That is, for a fixed ergodic $T$, the generic non-constant $f\in L^1$ has the averages $\mathbb{A}_N f(x)$ fluctuating around the mean infinitely often for almost every $x$. We also consider fluctuation for other stochastic processes like subsequences of the ergodic averages, convolution operators, weighted averages, uniform distribution and martingales. We will show that in general, in these settings fluctuation around the limit infinitely often persists as the generic behavior.
format Preprint
id arxiv_https___arxiv_org_abs_2404_11507
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Fluctuation of ergodic averages and other stochastic processes
Mondal, Sovanlal
Rosenblatt, Joe
Wierdl, Máté
Dynamical Systems
37A50 (Primary), 37A46, 37A05 (Secondary)
For an ergodic map $T$ and a non-constant, real-valued $f \in L^1$, the ergodic averages $\mathbb{A}_N f(x) = \frac{1} {N} \sum_{n=1}^N f(T^n x)$ converge a.e., but the convergence is never monotone. Depending on particular properties of the function $f$, the averages $\mathbb{A}_N f(x)$ may or may not actually fluctuate around the mean value infinitely often a.e. We will prove that a.e. fluctuation around the mean is the generic behavior. That is, for a fixed ergodic $T$, the generic non-constant $f\in L^1$ has the averages $\mathbb{A}_N f(x)$ fluctuating around the mean infinitely often for almost every $x$. We also consider fluctuation for other stochastic processes like subsequences of the ergodic averages, convolution operators, weighted averages, uniform distribution and martingales. We will show that in general, in these settings fluctuation around the limit infinitely often persists as the generic behavior.
title Fluctuation of ergodic averages and other stochastic processes
topic Dynamical Systems
37A50 (Primary), 37A46, 37A05 (Secondary)
url https://arxiv.org/abs/2404.11507