Orbitwise expansive maps

Fuente: arXiv
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Main Authors: Bhattacharjee, Debasish, Kobir, Humayan, Acharjee, Santanu
Format: Preprint
Published: 2025
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author Bhattacharjee, Debasish
Kobir, Humayan
Acharjee, Santanu
author_facet Bhattacharjee, Debasish
Kobir, Humayan
Acharjee, Santanu
contents This study defines an orbitwise expansive point (OE) as a point, such as $x$ in a metric space $(X,ρ)$, if there is a number $d>0$ such that the orbits of a few points inside an arbitrary open sphere will maintain a distance greater than $d$ from the corresponding points of the orbit of $x$ at least once. The point $x$ is referred to as the relatively orbitwise expansive point (ROE) in the previously described scenario if $d$ is replaced with the radius of the open sphere whose orbit is investigated and whose centre is $x$. %The function generating the orbit is considered to be continuous. We also define OE (ROE) set. We prove that arbitrary union of OE (ROE) set is again OE (ROE) set and every limit point of an OE set is an OE point. We show that, rather than the other way around, Utz's expansive map or Kato's CW-expansive map implies OE (ROE) map. We utilise the concept of OE(ROE) to analyse a time-varying dynamical system and investigate its relevance to certain traits associated with expansiveness.
format Preprint
id arxiv_https___arxiv_org_abs_2505_00048
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Orbitwise expansive maps
Bhattacharjee, Debasish
Kobir, Humayan
Acharjee, Santanu
Dynamical Systems
General Topology
54H20, 37B20
This study defines an orbitwise expansive point (OE) as a point, such as $x$ in a metric space $(X,ρ)$, if there is a number $d>0$ such that the orbits of a few points inside an arbitrary open sphere will maintain a distance greater than $d$ from the corresponding points of the orbit of $x$ at least once. The point $x$ is referred to as the relatively orbitwise expansive point (ROE) in the previously described scenario if $d$ is replaced with the radius of the open sphere whose orbit is investigated and whose centre is $x$. %The function generating the orbit is considered to be continuous. We also define OE (ROE) set. We prove that arbitrary union of OE (ROE) set is again OE (ROE) set and every limit point of an OE set is an OE point. We show that, rather than the other way around, Utz's expansive map or Kato's CW-expansive map implies OE (ROE) map. We utilise the concept of OE(ROE) to analyse a time-varying dynamical system and investigate its relevance to certain traits associated with expansiveness.
title Orbitwise expansive maps
topic Dynamical Systems
General Topology
54H20, 37B20
url https://arxiv.org/abs/2505.00048