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Main Authors: Geller, William, Misiurewicz, Michał, Sawicki, Damian
Format: Preprint
Published: 2021
Subjects:
Online Access:https://arxiv.org/abs/2109.15172
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author Geller, William
Misiurewicz, Michał
Sawicki, Damian
author_facet Geller, William
Misiurewicz, Michał
Sawicki, Damian
contents Coarse geometry studies metric spaces on the large scale. The recently introduced notion of coarse entropy is a tool to study dynamics from the coarse point of view. We prove that all isometries of a given metric space have the same coarse entropy and that this value is a coarse invariant. We call this value the coarse entropy of the space and investigate its connections with other properties of the space. We prove that it can only be either zero or infinity, and although for many spaces this dichotomy coincides with the subexponential--exponential growth dichotomy, there is no relation between coarse entropy and volume growth more generally. We completely characterise this dichotomy for spaces with bounded geometry and for quasi-geodesic spaces. As an application, we provide an example where coarse entropy yields an obstruction for a coarse embedding, where such an embedding is not precluded by considerations of volume growth.
format Preprint
id arxiv_https___arxiv_org_abs_2109_15172
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Coarse entropy of metric spaces
Geller, William
Misiurewicz, Michał
Sawicki, Damian
Metric Geometry
Dynamical Systems
Group Theory
51F30, 37B40
Coarse geometry studies metric spaces on the large scale. The recently introduced notion of coarse entropy is a tool to study dynamics from the coarse point of view. We prove that all isometries of a given metric space have the same coarse entropy and that this value is a coarse invariant. We call this value the coarse entropy of the space and investigate its connections with other properties of the space. We prove that it can only be either zero or infinity, and although for many spaces this dichotomy coincides with the subexponential--exponential growth dichotomy, there is no relation between coarse entropy and volume growth more generally. We completely characterise this dichotomy for spaces with bounded geometry and for quasi-geodesic spaces. As an application, we provide an example where coarse entropy yields an obstruction for a coarse embedding, where such an embedding is not precluded by considerations of volume growth.
title Coarse entropy of metric spaces
topic Metric Geometry
Dynamical Systems
Group Theory
51F30, 37B40
url https://arxiv.org/abs/2109.15172