arXiv subjects

Yuki Yayama

Publications and source records attributed to Yuki Yayama.

11 recordsLinked to original sources

arXiv2026

Existence of Gibbs measures for sequences of continuous functions

We give a necessary and sufficient condition for the existence of invariant Gibbs measures for sequences of continuous functions on one-sided subshifts and, more generally, for the existence of Gibbs measures. These extend the results of Kim [7] and Baker and Ghenciu [2], respectively, to sequences of continuous functions on one-sided subshifts. In particular, we characterize the existence of invariant Gibbs measures for subadditive sequences. For superadditive sequences on subshifts with the strong specification property, such a characterization gives a necessary and sufficient condition for the uniqueness of invariant Gibbs measures. We apply these results to study some problems in the theory of relative pressure and relative equilibrium states.

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arXiv2025

On Gibbs measures for almost additive sequences associated to some relative pressure functions

Given a weakly almost additive sequence of continuous functions with bounded variation $\mathcal{F}=\{\log f_n\}_{n=1}^{\infty}$ on a subshift $X$ over finitely many symbols, we study properties of a function $f$ on $X$ such that $\lim_{n\to\infty}\frac{1}{n}\int \log f_n dμ=\int f dμ$ for every invariant measure $μ$ on $X$. Under some conditions we construct a function $f$ on $X$ explicitly and study a relation between the property of $\mathcal{F}$ and some particular types of $f$. As applications we study images of Gibbs measures for continuous functions under one-block factor maps. We investigate a relation between the almost additivity of the sequences associated to relative pressure functions and the fiber-wise sub-positive mixing property of a factor map. For a special type of one-block factor maps between shifts of finite type, we study necessary and sufficient conditions for the image of a one-step Markov measure to be a Gibbs measure for a continuous function.

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arXiv2021

Relative pressure functions and their equilibrium states

For a subshift $(X, σ_X)$ and a subadditive sequence $\mathcal{F}=\{\log f_n\}_{n=1}^{\infty}$ on $X$, we study equivalent conditions for the existence of $h\in C(X)$ such that $\lim_{n\rightarrow\infty}(1/{n})\int \log f_n d μ=\int h d μ$ for every invariant measure $μ$ on $X$. For this purpose, we first we study necessary and sufficient conditions for $\mathcal{F}$ to be an asymptotically additive sequence in terms of certain properties for periodic points. For a factor map $π: X\rightarrow Y$, where $(X, σ_X)$ is an irreducible shift of finite type and $(Y, σ_Y)$ is a subshift, applying our results and the results obtained by Cuneo [7] on asymptotically additive sequences, we study the existence of $h$ with regard to a subadditive sequence associated to a relative pressure function. This leads to a characterization of the existence of a certain type of continuous compensation function for a factor map between subshifts. As an application, we study we study the projection $πμ$ of an invariant weak Gibbs measure $μ$ for a continuous function on an irreducible shift of finite type.

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arXiv2018

Hidden Gibbs measures on shift spaces over countable alphabets

We study the thermodynamic formalism for particular types of sub-additive sequences on a class of subshifts over countable alphabets. The subshifts we consider include factors of irreducible countable Markov shifts under certain conditions. We show the variational principle for topological pressure. We also study conditions for the existence and uniqueness of invariant ergodic Gibbs measures and the uniqueness of equilibrium states. As an application, we extend the theory of factors of (generalized) Gibbs measures on subshifts on finite alphabets to that on certain subshifts over countable alphabets.

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arXiv2015

Weak Gibbs measures as Gibbs measures for asymptotically additive sequences

In this note we prove that every weak Gibbs measure for an asymptotically additive sequences is a Gibbs measure for another asymptotically additive sequence. In particular, a weak Gibbs measure for a continuous potential is a Gibbs measure for an asymptotically additive sequence. This allows, for example, to apply recent results on dimension theory of asymptotically additive sequences to study multifractal analysis for weak Gibbs measure for continuous potentials.

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arXiv2014

On factors of Gibbs measures for almost additive potentials

Let $(X, σ_X), (Y, σ_Y)$ be one-sided subshifts with the specification property and $π:X\rightarrow Y$ a factor map. Let $μ$ be a unique invariant Gibbs measure for a sequence of continuous functions $\F=\{\log f_n\}_{n=1}^{\infty}$ on $X$, which is an almost additive potential with bounded variation. We show that $πμ$ is also a unique invariant Gibbs measure for a sequence of continuous functions $\G=\{\log g_n\}_{n=1}^{\infty}$ on $Y$. When $(X, σ_X)$ is a full shift, we characterize $\G$ and $μ$ by using relative pressure. This almost additive potential $\G$ is a generalization of a continuous function found by Pollicott and Kempton in their work on the images of Gibbs measures for continuous functions under factor maps. We also consider the following question: Given a unique invariant Gibbs measure $ν$ for a sequence of continuous functions $\F_2$ on $Y$, can we find an invariant Gibbs measure $μ$ for a sequence of continuous functions $\F_1$ on $X$ such that $πμ=ν$? We show that such a measure exists under a certain condition. If $(X, σ_X)$ is a full shift and $ν$ is a unique invariant Gibbs measure for a function in the Bowen class, then we can find a preimage $μ$ of $ν$ which is a unique invariant Gibbs measure for a function in the Bowen class.

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arXiv2013

Zero temperature limits of Gibbs states for almost-additive potentials

This paper is devoted to study ergodic optimisation problems for almost-additive sequences of functions (rather than a fixed potential) defined over countable Markov shifts (that is a non-compact space). Under certain assumptions we prove that any accumulation point of a family of Gibbs equilibrium measures is a maximising measure. Applications are given in the study of the joint spectral radius and to multifractal analysis of Lyapunov exponent of non-conformal maps.

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arXiv2011

Almost-additive thermodynamic formalism for countable Markov shifts

We introduce a definition of pressure for almost-additive sequences of continuous functions defined over (non-compact) countable Markov shifts. The variational principle is proved. Under certain assumptions we prove the existence of Gibbs and equilibrium measures. Applications are given to the study of maximal Lypaunov exponents of product of matrices.

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arXiv2009

Existence of a measurable saturated compensation function between subshifts and its applications

We show the existence of a bounded Borel measurable saturated compensation function for a factor map between subshifts. As an application, we find the Hausdorff dimension and measures of full Hausdorff dimension for a compact invariant set of an expanding nonconformal map on the torus given by an integer-valued diagonal matrix. These problems were studied in [19] for a compact invariant set whose symbolic representation is a shift of finite type under the condition of the existence of a saturated compensation function. We extend the results by presenting a formula for the Hausdorff dimension for a compact invariant set whose symbolic representation is a subshift without the condition and characterizing the invariant ergodic measures of full dimension as the ergodic equilibrium states of a constant multiple of a measurable compensation function. For a compact invariant set whose symbolic representation is a topologically mixing shift of finite type, we study uniqueness and the properties for the unique invariant ergodic measure of full dimension by using a measurable compensation function. Our positive results narrow the possibility of where an example having more than one measure of full dimension can be found.

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arXiv2008

Dimensions of compact invariant sets of some expanding maps

We study the Hausdorff dimension and measures of full Hausdorff dimension for a compact invariant set of an expanding nonconformal map on the torus given by an integer-valued diagonal matrix. The Hausdorff dimension of a "general Sierpinski carpet" was found by McMullen and Bedford and the uniqueness of the measure of full Hausdorff dimension in some cases was proved by Kenyon and Peres. We extend these results by using compensation functions to study a general Sierpinski carpet represented by a shift of finite type. We give some conditions under which a general Sierpinski carpet has a unique measure of full Hausdorff dimension, and study the properties of the unique measure.

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arXiv2008

Markov partitions reflecting the geometry of x2,x3

We give an explicit geometric description of the $\times2,\times3$ system, and use his to study a uniform family of Markov partitions related to those of Wilson and Abramov. The behaviour of these partitions is stable across expansive cones and transitions in this behaviour detects the non-expansive lines.

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