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Yonatan Gutman

Publications and source records attributed to Yonatan Gutman.

45 records · Page 3Linked to original sources
arXiv2013

Dynamical Embedding in Cubical Shifts & the Topological Rokhlin and Small Boundary Properties

According to a conjecture of Lindenstrauss and Tsukamoto, a topological dynamical system $(X,T)$ is embeddable in the $d$-cubical shift $(([0,1]^{d})^{\mathbb{Z}},\ shift)$ if both its mean dimension and periodic dimension are strictly bounded by $\frac{d}{2}$. We verify the conjecture for the class of systems admitting finite dimensional non-wandering sets (under the additional assumption of closed periodic points set). The main tool in the proof is the new concept of local markers. Continuing the investigation of (global) markers initiated in previous work it is shown that the marker property is equivalent to a topological version of the Rokhlin Lemma. Moreover new classes of systems are found to have the marker property, in particular, extensions of aperiodic systems with a countable number of minimal subsystems. Extending work of Lindenstrauss we show that for systems with the marker property vanishing mean dimension is equivalent to the small boundary property. Finally we answer a question by Downarowicz in the affirmative: the small boundary property is equivalent to admitting a zero-dimensional isomorphic extension.

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arXiv2012

A Juzvinski\uı Addition Theorem for Finitely Generated Free Groups Actions

The classical Juzvinskiĭ Addition Theorem states that the entropy of an automorphism of a compact group decomposes along invariant subgroups. Thomas generalized the theorem to a skew-product setting. Using L. Bowen's f-invariant we prove the addition theorem for actions of finitely generated free groups on skew-products with compact totally disconnected groups or compact Lie groups (correcting an error from [Bo10c]) and discuss examples.

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arXiv2012

Mean dimension and a sharp embedding theorem: extensions of aperiodic subshifts

We show that if $(X,T)$ is an extension of an aperiodic subshift (a subsystem of $({1,2,...,l}^{\mathbb{Z}},\mathrm{shift})$ for some $l\in\mathbb{N}$) and has mean dimension $mdim(X,T)<\frac{D}{2}$ $(D\in \mathbb{N}$), then it embeds equivariantly in (([0,1]^{D})^{\mathbb{Z}},\mathrm{shift})$. The result is sharp. If $(X,T)$ is an extension of an aperiodic zero-dimensional system then it embeds equivariantly in $(([0,1]^{D+1})^{\mathbb{Z}},\mathrm{shift})$.

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arXiv2012

Rank as a function of measure

We establish certain topological properties of rank understood as a function on the set of invariant measures on a topological dynamical system. To be exact, we show that rank is of Young class LU (i.e., it is the limit of an increasing sequence of upper semicontinuous functions)

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arXiv2012

Minimal hyperspace actions of homeomorphism groups of h-homogeneous spaces

Let X be a h-homogeneous zero-dimensional compact Hausdorff space, i.e. X is a Stone dual of a homogeneous Boolean algebra. Using the dual Ramsey theorem and a detailed combinatorial analysis of what we call stable collections of subsets of a finite set, we obtain a complete list of the minimal sub-systems of the compact dynamical system (Exp(Exp(X)),Homeo(X)), where Exp(X) stands for the hyperspace comprising the closed subsets of X equipped with the Vietoris topology. The importance of this dynamical system stems from Uspenskij's characterization of the universal ambit of G = Homeo(X). The results apply to X = C the Cantor set, the generalized Cantor sets X = {0,1}^kappa for non-countable cardinals kappa, and to several other spaces. A particular interesting case is X = beta(omega) \ omega, where beta(omega) denotes the Stone-Cech compactification of the natural numbers. This space, called the corona or the remainder of omega, has been extensively studied in the fields of set theory and topology.

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arXiv2011

The universal minimal space for groups of homeomorphisms of h-homogeneous spaces

Let X be a h-homogeneous zero-dimensional compact Hausdorff space, i.e. X is a Stone dual of a homogeneous Boolean algebra. It is shown that the universal minimal space M(G) of the topological group G=Homeo(X), is the space of maximal chains on X introduced by Uspenskij. If X is metrizable then clearly X is homeomorphic to the Cantor set and the result was already known (Glasner-Weiss 2003). However many new examples arise for non-metrizable spaces. These include, among others, the generalized Cantor sets X={0,1}^{kappa} for non-countable cardinals kappa, and the corona or remainder of omega, X=beta(omega) \ omega, where beta(omega) denotes the Stone-Cech compactification of the natural numbers.

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arXiv2006

On processes which cannot be distinguished by finitary observation

A function $J$ defined on a family $C$ of stationary processes is finitely observable if there is a sequence of functions $s_n$ such that $s_n(x_1 ... x_n)\to J(X)$ in probability for every process $X=(x_n)\in C$. Recently, Ornstein and Weiss roved the striking result that if $C$ is the class of aperiodic ergodic finite valued processes, then the only finitely observable isomorphism invariant on $C$ is entropy. We sharpen this in several ways. Our main theorem is that if $X \to Y$ is a zero-entropy extension of finite entropy ergodic systems and $C$ is the family of processes arising from $X$ and $Y$, then every finitely observable function on $C$ is constant. This implies Ornstein and Weiss' result, and extends it to many other families of processes, e.g. it shows that there are no nontrivial finitely observable isomorphism invariants for processes arising from Kronecker systems, mild and strong mixing zero entropy systems. It also implies that any finitely observable isomorphism invariant defined on the family of processes arising from irrational rotations must be constant for rotations belonging to a set of full Lebesgue measure.

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