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Displaying 361 –
380 of
490
Une substitution est un morphisme de monoïdes libres :
chaque lettre a pour image un mot, et
l'image d'un mot est la concaténation des images de ses lettres.
Cet article introduit une généralisation de la notion de substitution,
où l'image d'une lettre n'est plus un mot mais un motif, c'est-à-dire
un “mot à trous”, l'image d'un mot étant obtenue en raccordant les
motifs correspondant à chacune de ses lettres à l'aide de règles
locales. On caractérise
complètement les substitutions par des motifs...
Nous donnons une représentation géométrique des suites doubles uniformément récurrentes de fonction de complexité rectangulaire . Nous montrons que ces suites codent l’action d’une -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.
Viene considerato il problema della stabilità di un punto fisso per un germe di diffeomorfismo di più variabili complesse cercando un coniugio con la sua parte lineare: Problema del centro di Schröder-Siegel. Dopo aver formulato il problema e ricordato i principali risultati nel caso di diffeomorfismi olomorfi, mostriamo come estendere il problema ad alcune situazioni non olomorfe, in particolare ci interesseremo al caso di germi Gevrey. Concluderemo con un'applicazione rivolta a mostrare la stabilità...
This article studies the summability of first integrals of a -non-integrable resonant Hamiltonian system. The first integrals are expressed in terms of formal exponential transseries and their Borel sums. Smooth Liouville integrability and a relation to the Birkhoff transformation are discussed from the point of view of the summability.
We consider S-unimodal Misiurewicz maps T with a flat critical point c and show that they exhibit ergodic properties analogous to those of interval maps with indifferent fixed (or periodic) points. Specifically, there is a conservative ergodic absolutely continuous σ-finite invariant measure μ, exact up to finite rotations, and in the infinite measure case the system is pointwise dual ergodic with many uniform and Darling-Kac sets. Determining the order of return distributions to suitable reference...
While looking for additional integrals of motion of several minimally superintegrable systems in static electric and magnetic fields, we have realized that in some cases Lie point symmetries of Euler-Lagrange equations imply existence of explicitly time-dependent integrals of motion through Noether’s theorem. These integrals can be combined to get an additional time-independent integral for some values of the parameters of the considered systems, thus implying maximal superintegrability. Even for...
The spherical version of the two-dimensional central harmonic oscillator, as well as the spherical Kepler (Schrödinger) potential, are superintegrable systems with quadratic constants of motion. They belong to two different spherical "Smorodinski-Winternitz" families of superintegrable potentials. A new superintegrable oscillator have been recently found in S². It represents the spherical version of the nonisotropic 2:1 oscillator and it also belongs to a spherical family of quadratic superintegrable...
Let T be a positive linear contraction of of a σ-finite measure space (X,Σ,μ) which overlaps supports. In general, T need not be completely mixing, but it is in the following cases: (i) T is the Frobenius-Perron operator of a non-singular transformation ϕ (in which case complete mixing is equivalent to exactness of ϕ). (ii) T is a Harris recurrent operator. (iii) T is a convolution operator on a compact group. (iv) T is a convolution operator on a LCA group.
We introduce an invariant of cohomology in Bernoulli shifts, which is used to answer a question about cohomology of Hölder functions with finitary functions whose coding time is integrable. When restricted to the class of Hölder functions, this invariant even provides a criterion of cohomology.
Nous construisons des mesures selles (dans un sens faible) pour les endomorphismes holomorphes de .
Soit la rotation sur le cercle d’angle irrationnel , soit
une marche aléatoire transiente sur . Soit et , nous étudions la convergence faible de la suite
On démontre que dans toute surface rationnelle, non-isomorphe au plan projectif, il existe une feuilletage analytique rigide, possédant des feuilles algébriques et n’ayant que des singularités isolées.
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