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Joseph Auslander

Publications and source records attributed to Joseph Auslander.

10 recordsLinked to original sources
arXiv2025

Wandering Flows on the Plane

We study planar flows without non-wandering points and prove several properties of these flows in relation with their prolongational relation. The main results of this article are that a planar (regular) wandering flow has no generalized recurrence and has only two topological invariants: the space of its orbits and its prolongational relation (or, equivalently, its smallest stream). As a byproduct, our results show that, even in absence of any type of recurrence, the stream of a flow contains fundamental information on its behavior.

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arXiv2024

Some relations in topological dynamics

Relations always play an important role in the study of topological dynamics. Proximal, distal and almost periodic relations are well studied in literature. We further this direction and analogously study the strongly proximal and weakly distal relations. This gives a new class of flows - the weakly distal flows. We observe that the well known Morse-Thue substitution flows and Chacon transformations are weakly distal.

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arXiv2020

On Almost periodicity and minimality for semiflows

In topological dynamics, the dynamical behavior sometimes has a sharp contrast when the action is by semigroups or monoids to when the action is by groups. In this article we bring out this contrast while discussing the equivalence of almost periodicity and minimality, and some implications when every point is an almost periodic point.

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arXiv2018

Minimality, distality and equicontinuity for semigroup actions on compact Hausdorff spaces

Let $π\colon T\times X\rightarrow X$ with phase map $(t,x)\mapsto tx$, denoted $(π,T,X)$, be a \textit{semiflow} on a compact Hausdorff space $X$ with phase semigroup $T$. If each $t\in T$ is onto, $(π,T,X)$ is called surjective; and if each $t\in T$ is 1-1 onto $(π,T,X)$ is called invertible and in latter case it induces $π^{-1}\colon X\times T\rightarrow X$ by $(x,t)\mapsto xt:=t^{-1}x$, denoted $(π^{-1},X,T)$. In this paper, we show that $(π,T,X)$ is equicontinuous surjective iff it is uniformly distal iff $(π^{-1},X,T)$ is equicontinuous surjective. As applications of this theorem, we also consider the minimality, distality, and sensitivity of $(π^{-1},X,T)$ if $(π,T,X)$ is invertible with these dynamics. We also study the pointwise recurrence and Gottschalk's weak almost periodicity of $\mathbb{Z}$-flow with compact zero-dimensional phase space.

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arXiv2018

On transitivity dynamics of topological semiflows

Let $T\times X\rightarrow X, (t,x)\mapsto tx$, be a topological semiflow on a topological space $X$ with phase semigroup $T$. We introduce and discuss in this paper various transitivity dynamics of $(T,X)$.

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arXiv2016

Variations on the Concept of Topological Transitivity

We describe various strengthenings of the concept of topological transitivity. Especially when one departs from the family of invertible systems, a number of interesting properties arise. We present the architecture of implications among ten reasonable notions of transitivity.

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arXiv2014

Dynamics of Induced Systems

In this paper, we study the dynamical properties of actions on the space of compact subsets of the phase space. More precisely, if $X$ is a metric space, let $2^X$ denote the space of non-empty compact subsets of $X$ provided with the Hausdorff topology. If $f$ is a continuous self-map on $X$, there is a naturally induced continuous self-map $f_*$ on $2^X$. Our main theme is the interrelation between the dynamics of $f$ and $f_*$. For such a study, it is useful to consider the space $\mathcal{C}(K,X)$ of continuous maps from a Cantor set $K$ to $X$ provided with the topology of uniform convergence, and $f_*$ induced on $\mathcal{C}(K,X)$ by composition of maps. We mainly study the properties of transitive points of the induced system $(2^X,f_*)$ both topologically and dynamically, and give some examples. We also look into some more properties of the system $(2^X,f_*)$.

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arXiv2011

Reflections on equicontinuity

We study different conditions which turn out to be equivalent to equicontinuity for a transitive compact Hausdorff flow with a general group action. Among them are a notion of "regional" equicontinuity, also known as "Furstenberg" condition, and the condition that every point of the phase space is almost automorphic. Then we study relations on the phase space arising from dynamical properties, among them the regionally proximal relation and two relations introduced by Veech. We generalize Veech's results for minimal actions of non-Abelian groups preserving a probability measure with respect to the regionally proximal relation. We provide proofs in the framework of dynamical systems rather than harmonic analysis as given by Veech.

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arXiv2010

Compactifications of Dynamical Systems

While compactness is an essential assumption for many results in dynamical systems theory, for many applications the state space is only locally compact. Here we provide a general theory for compactifying such systems, i.e. embedding them as invariant open subsets of compact systems. In the process we don't want to introduce recurrence which was not there in the original system. For example if a point lies on an orbit which remains in any compact set for only a finite span of time then the point becomes non-wandering if we use the one-point compactification. Instead, we develop here the appropriate theory of dynamic compactification.

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