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Quasi-periodic solutions with Sobolev regularity of NLS on 𝕋 d with a multiplicative potential

Massimiliano Berti, Philippe Bolle (2013)

Journal of the European Mathematical Society

We prove the existence of quasi-periodic solutions for Schrödinger equations with a multiplicative potential on 𝕋 d , d 1 , finitely differentiable nonlinearities, and tangential frequencies constrained along a pre-assigned direction. The solutions have only Sobolev regularity both in time and space. If the nonlinearity and the potential are C then the solutions are C . The proofs are based on an improved Nash-Moser iterative scheme, which assumes the weakest tame estimates for the inverse linearized operators...

Quelques nouveaux invariants des difféomorphismes Morse--Smale d'une surface

Rémi Langevin (1993)

Annales de l'institut Fourier

Soit f un difféomorphisme Morse-Smale d’une surface fermée. À une courbe instable de comportement 1 par rapport à un attracteur A de f correspond une courbe fermée sur un des tores (Bassin ( A ) - A ) / ( f ) . Cette remarque nous permettra de définir de nouveaux invariants de conjugaison de f . Nous en déduisons aussi un moyen d’écrire explicitement une puissance de f comme le produit du temps 1 d’un champ de vecteurs Morse-Smale topologique par des isotopies à support des disques et des twists de Dehn de supports...

Quelques résultats sur la dimension de Hausdorff des ensembles de Julia des polynômes quadratiques

Olivier Bodart, Michel Zinsmeister (1996)

Fundamenta Mathematicae

This paper deals with the Hausdorff dimension of the Julia set of quadratic polynomials. It is divided in two parts. The first aims to compute good numerical approximations of the dimension for hyperbolic points. For such points, Ruelle’s thermodynamical formalism applies, hence computing the dimension amounts to computing the zero point of a pressure function. It is this pressure function that we approximate by a Monte-Carlo process combined with a shift method that considerably decreases the computational...

Questions about Polynomial Matings

Xavier Buff, Adam L. Epstein, Sarah Koch, Daniel Meyer, Kevin Pilgrim, Mary Rees, Tan Lei (2012)

Annales de la faculté des sciences de Toulouse Mathématiques

We survey known results about polynomial mating, and pose some open problems.

Random orderings and unique ergodicity of automorphism groups

Omer Angel, Alexander S. Kechris, Russell Lyons (2014)

Journal of the European Mathematical Society

We show that the only random orderings of finite graphs that are invariant under isomorphism and induced subgraph are the uniform random orderings. We show how this implies the unique ergodicity of the automorphism group of the random graph. We give similar theorems for other structures, including, for example, metric spaces. These give the first examples of uniquely ergodic groups, other than compact groups and extremely amenable groups, after Glasner andWeiss’s example of the group of all permutations...

Random permutations and unique fully supported ergodicity for the Euler adic transformation

Sarah Bailey Frick, Karl Petersen (2008)

Annales de l'I.H.P. Probabilités et statistiques

There is only one fully supported ergodic invariant probability measure for the adic transformation on the space of infinite paths in the graph that underlies the eulerian numbers. This result may partially justify a frequent assumption about the equidistribution of random permutations.

Randomly connected dynamical systems - asymptotic stability

Katarzyna Horbacz (1998)

Annales Polonici Mathematici

We give sufficient conditions for asymptotic stability of a Markov operator governing the evolution of measures due to the action of randomly chosen dynamical systems. We show that the existence of an invariant measure for the transition operator implies the existence of an invariant measure for the semigroup generated by the system.

Rank gradient, cost of groups and the rank versus Heegaard genus problem

Miklós Abért, Nikolay Nikolov (2012)

Journal of the European Mathematical Society

We study the growth of the rank of subgroups of finite index in residually finite groups, by relating it to the notion of cost. As a by-product, we show that the ‘rank vs. Heegaard genus’ conjecture on hyperbolic 3-manifolds is incompatible with the ‘fixed price problem’ in topological dynamics.

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