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# Documents  Mercat, Paul | enregistrements trouvés : 7

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## Interview au CIRM : Pascal Hubert Hubert, Pascal | CIRM H

Post-edited

Outreach;Mathematics Education and Popularization of Mathematics

Pascal Hubert est mathématicien, professeur au sein d'Aix-Marseille Université et directeur de la FRUMAM.
Il parle ici de son grand-père, qui lui a donné le goût des mathématiques, de ses recherches, de la richesse mathématique marseillaise, de sa collaboration avec Artur Avila (Médaille Fields 2014), etc. Artur Avila que nous avons pu contacter avant l'interview de Pascal Hubert, et qui nous a demandé de lui parler de Jean-Christophe Yoccoz...
Pascal Hubert est mathématicien, professeur au sein d'Aix-Marseille Université et directeur de la FRUMAM.
Il parle ici de son grand-père, qui lui a donné le goût des mathématiques, de ses recherches, de la richesse mathématique marseillaise, de sa collaboration avec Artur Avila (Médaille Fields 2014), etc. Artur Avila que nous avons pu contacter avant l'interview de Pascal Hubert, et qui nous a demandé de lui parler de Jean-Christophe Yoccoz...

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## Dense subgroups in simple groups - Lecture 2 Benoist, Yves | CIRM H

Post-edited

Research schools;Lie Theory and Generalizations

In this series of lectures, we will focus on simple Lie groups, their dense subgroups and the convolution powers of their measures. In particular, we will dicuss the following two questions.
Let G be a Lie group. Is every Borel measurable subgroup of G with maximal Hausdorff dimension equal to the group G?
Is the convolution of sufficiently many compactly supported continuous functions on G always continuously differentiable?
Even though the answer to these questions is no when G is abelian, the answer is yes when G is simple. This is a joint work with N. de Saxce. First, I will explain the history of these two questions and their interaction. Then, I will relate these questions to spectral gap properties. Finally, I will discuss these spectral gap properties.
In this series of lectures, we will focus on simple Lie groups, their dense subgroups and the convolution powers of their measures. In particular, we will dicuss the following two questions.
Let G be a Lie group. Is every Borel measurable subgroup of G with maximal Hausdorff dimension equal to the group G?
Is the convolution of sufficiently many compactly supported continuous functions on G always continuously differentiable?
Even though the ...

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## Dynamics on homogeneous spaces and Diophantine approximation Ghosh, Anish | CIRM H

Multi angle

Research schools;Dynamical Systems and Ordinary Differential Equations;Number Theory

I will discuss approaches to several problems concerning values of linear and quadratic forms using the ergodic theory of group actions on the space of unimodular lattices, and more generally, on homogeneous spaces of semisimple Lie groups.

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## Dynamics on quotients of SL(2,C) by discrete subgroups - Lecture 2 Schapira, Barbara | CIRM H

Multi angle

Research schools;Dynamical Systems and Ordinary Differential Equations

We will discuss old and recent results on topological and measurable dynamics of diagonal and unipotent flows on frame bundles and unit tangent bundles over hyperbolic manifolds. The first lectures will be a good introduction to the subject for young researchers.

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## Shrinking targets on homogeneous spaces and improving Dirichlet's Theorem Kleinbock, Dmitry | CIRM H

Multi angle

Research schools;Dynamical Systems and Ordinary Differential Equations;Number Theory

Optimal results on the improvements to Dirichlet's Theorem are obtained in the one-dimensional case. For simultaneous approximation the problem is open. I will describe reduction of the problem to dynamics both in one-dimensional case (via continued fractions) and for higher dimensions (via diagonal flows on the space of lattices). If time allows I'll mention an inhomogeneous version which is easier than the homogeneous one. Joint work with Nick Wadleigh. Optimal results on the improvements to Dirichlet's Theorem are obtained in the one-dimensional case. For simultaneous approximation the problem is open. I will describe reduction of the problem to dynamics both in one-dimensional case (via continued fractions) and for higher dimensions (via diagonal flows on the space of lattices). If time allows I'll mention an inhomogeneous version which is easier than the homogeneous one. Joint work with Nick ...

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## Counting and equidistribution of integral representations by quadratic norm forms in positive characteristic? Paulin, Frédéric | CIRM H

Multi angle

Research schools;Dynamical Systems and Ordinary Differential Equations;Number Theory

In this talk, we will prove the projective equidistribution of integral representations by quadratic norm forms in positive characteristic, with error terms, and deduce asymptotic counting results of these representations. We use the ergodic theory of lattice actions on Bruhat-Tits trees, and in particular the exponential decay of correlation of the geodesic flow on trees for Hölder variables coming from symbolic dynamics techniques.

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## Yet another characterization of the Pisot conjecture Mercat, Paul | CIRM H

Multi angle

Research talks;Computer Science;Dynamical Systems and Ordinary Differential Equations;Number Theory

In the way of Arnoux-Ito, we give a general geometric criterion for a subshift to be measurably conjugated to a domain exchange and to a translation on a torus. For a subshift coming from an unit Pisot irreducible substitution, we will see that it becomes a simple topological criterion. More precisely, we define a topology on $\mathbb{Z}^d$ for which the subshift has pure discrete spectrum if and only if there exists a domain of the domain exchange on the discrete line that has non-empty interior. We will see how we can compute exactly such interior using regular languages. This gives a way to decide the Pisot conjecture for any example of unit Pisot irreducible substitution.
Joint work with Shigeki Akiyama.
In the way of Arnoux-Ito, we give a general geometric criterion for a subshift to be measurably conjugated to a domain exchange and to a translation on a torus. For a subshift coming from an unit Pisot irreducible substitution, we will see that it becomes a simple topological criterion. More precisely, we define a topology on $\mathbb{Z}^d$ for which the subshift has pure discrete spectrum if and only if there exists a domain of the domain ...

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