Nous donnons une représentation géométrique des suites doubles uniformément récurrentes de fonction de complexité rectangulaire $mn+n$. Nous montrons que ces suites codent l’action d’une ${\mathbb{Z}}^2$-action définie par deux rotations irrationnelles sur le cercle unité. La preuve repose sur une étude des suites doubles dont les lignes sont des suite sturmiennes de même langage.

Étant donné un arbre $T$ et un groupe $\Gamma$ d’automorphismes de $T$, nous étudions les propriétés markoviennes du flot géodésique sur le quotient de l’espace des géodésiques de $T$ par $\Gamma$. Par exemple, quand $T$ est l’arbre de Bruhat-Tits d’un groupe algébrique linéaire connexe semi-simple $\underline{G}$ de rang 1 sur un corps local non archimédien $\widehat{K}$ et si $\Gamma$ est un réseau (éventuellement non uniforme) dans $\underline{G}\left(\widehat{K}\right)$, nous montrons que l’action des puissances paires de la transformation géodésique est Bernoulli d’entropie finie sur...

We study a class of stationary finite state processes, called quasi-Markovian, including in particular the processes whose law is a Gibbs measure as defined by Bowen. We show that, if a factor with integrable coding time of a quasi-Markovian process is maximal in entropy, then this factor splits off, which means that it admits a Bernoulli shift as an independent complement. If it is not maximal in entropy, then we can find a splitting finite extension of this factor, which generalizes a theorem...

We consider subshifts arising from primitive substitutions, which are known to be uniquely ergodic dynamical systems. In order to precise this point, we introduce a symbolic notion of discrepancy. We show how the distribution of such a subshift is in part ruled by the spectrum of the incidence matrices associated with the underlying substitution. We also give some applications of these results in connection with the spectral study of substitutive dynamical systems.

We prove that ${𝒞}^r$ maps with $r\>1$ on a compact surface have symbolic extensions, i.e., topological extensions which are subshifts over a finite alphabet. More precisely we give a sharp upper bound on the so-called symbolic extension entropy, which is the infimum of the topological entropies of all the symbolic extensions. This answers positively a conjecture of S. Newhouse and T. Downarowicz in dimension two and improves a previous result of the author [11].

On donne une condition combinatoire effective suffisante pour que le sytème dynamique associé à une substitution de type Pisot ait un spectre purement discret. Dans le cas unimodulaire, cette condition est nécessaire dès que la substitution n'a qu'un cobord trivial ; elle est vérifiée si et seulement si le fractal de Rauzy associé à la substitution engendre un pavage auto-similaire et périodique. On en déduit des conditions de connexité des fractals de Rauzy.

Let X be a locally compact, separable metric space. We prove that $di{m}_{T}X=infdi{m}_L{X}^{\text{'}}:X^{\text{'}}ishomeomorphictoX$, where $di{m}_{L}X$ and $di{m}_{T}X$ stand for the concentration dimension and the topological dimension of X, respectively.

A finite-state stationary process is called (one- or two-sided) super-K if its (one- or two-sided) super-tail field-generated by keeping track of (initial or central) symbol counts as well as of arbitrarily remote names-is trivial. We prove that for every process (α,T) which has a direct Bernoulli factor there is a generating partition β whose one-sided super-tail equals the usual one-sided tail of β. Consequently, every K-process with a direct Bernoulli factor has a one-sided super-K generator....

We prove that the automorphism group of the random lattice is not amenable, and we identify the universal minimal flow for the automorphism group of the random distributive lattice.

By a dynamical system $(X,T)$ we mean the action of the semigroup $({\mathbb{Z}}^{+},+)$ on a metrizable topological space $X$ induced by a continuous selfmap $T:X\to X$. Let $M\left(X\right)$ denote the set of all compatible metrics on the space $X$. Our main objective is to show that a selfmap $T$ of a compact space $X$ is a Banach contraction relative to some $d_1\in M\left(X\right)$ if and only if there exists some $d_2\in M\left(X\right)$ which, regarded as a $1$-cocycle of the system $(X,T)\times (X,T)$, is a coboundary.

If φ is a Pisot substitution of degree d, then the inflation and substitution homeomorphism Φ on the tiling space ${}_{\Phi }$ factors via geometric realization onto a d-dimensional solenoid. Under this realization, the collection of Φ-periodic asymptotic tilings corresponds to a finite set that projects onto the branch locus in a d-torus. We prove that if two such tiling spaces are homeomorphic, then the resulting branch loci are the same up to the action of certain affine maps on the torus.

For a self-map of a compactum we give a necessary and sufficient condition for the chain recurrent set to be precisely the set of periodic points.