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Nombre de programmes trouvés : 4989
Cours magistraux

le (55m57s)

E. Peyre - Slopes and distribution of points (part3)

The distribution of rational points of bounded height on algebraic varieties is far from uniform. Indeed the points tend to accumulate on thin subsets which are images of non-trivial finite morphisms. The problem is to find a way to characterise these thin subsets. The slopes introduced by Jean-Benoît Bost are a useful tool for this problem. These lectures will present several cases in which this approach is fruitful. We shall also describe the notion of locally accumulating subvarieties which arise when one considers rational points of ...
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Cours magistraux

le (1h28m48s)

E. Peyre - Slopes and distribution of points (part4)

The distribution of rational points of bounded height on algebraic varieties is far from uniform. Indeed the points tend to accumulate on thin subsets which are images of non-trivial finite morphisms. The problem is to find a way to characterise these thin subsets. The slopes introduced by Jean-Benoît Bost are a useful tool for this problem. These lectures will present several cases in which this approach is fruitful. We shall also describe the notion of locally accumulating subvarieties which arise when one considers rational points of ...
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Conférences

le (1h1m14s)

A. von Pippich - An analytic class number type formula for PSL2(Z)

For any Fuchsian subgroup Γ⊂PSL2(R) of the first kind, Selberg introduced the Selberg zeta function in analogy to the Riemann zeta function using the lengths of simple closed geodesics on Γ∖H instead of prime numbers. In this talk, we report on a formula that determines the special value at s=1 of the derivative of the Selberg zeta function for Γ=PSL2(Z). This formula is obtained as an application of a generalized Riemann-Roch isometry for the trivial sheaf on ¯¯¯¯¯¯¯¯¯¯¯Γ∖H, equipped with the Poincaré metric. This is joint ...
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Conférences

le (1h3m1s)

Y. Tang - Exceptional splitting of reductions of abelian surfaces with real multiplication

Chavdarov and Zywina showed that after passing to a suitable field extension, every abelian surface A with real multiplication over some number field has geometrically simple reduction modulo p for a density one set of primes p. One may ask whether its complement, the density zero set of primes p such that the reduction of A modulo p is not geometrically simple, is infinite. Such question is analogous to the study of exceptional mod p isogeny between two elliptic curves in the recent work of Charles. ...
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Conférences

le (1h2m0s)

S.Rigot - Besicovitch covering property in sub-Riemannian geometry

The Besicovitch covering property originates from works of Besicovitch about differentiation of measures in Euclidean spaces. It can more generally be used as a usefull tool to deduce global properties of a metric space from local ones. We will discuss in this talk the validity or non validity of the Besicovitch covering property on stratified groups equipped with sub Riemannian distances (Carnot groups) and more generally on graded groups equipped with homogeneous distances. We will illustrate these results with explicit examples in the Heisenberg group. ...
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Conférences

le (54m1s)

Christian Gérard - Aspects de la théorie quantique des champs en espace-temps courbe

La théorie quantique des champs est formulée d'habitude sur l'espace-temps plat de Minkowski. L'extension de ce cadre à des espaces-temps généraux permet de mettre en lumière de nouveaux phénomènes quantiques qui surviennent en présence d'un champ gravitationnel fort. Nous présenterons tout d'abord le cadre algébrique de la théorie des champs libres en espace-temps courbe, en traitant le cas modèle d'un champ de Klein-Gordon. Dans une deuxième partie nous aborderons les difficultés nouvelles dues à l'absence d'un groupe d'isométries sur un espace-temps courbe, qui se ...
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Témoignages

le (2m4s)

[#4] Atelier débat - L'univers du jeu vidéo : une industrie en plein bouleversements !

L’intervention de spécialistes (Stephane NATKIN -CNAM et Vincianne ZABAN -PARIS XIII) du secteur du jeu vidéo permet d’éclairer les développements de ce secteur, tant sur la question de l’apparition ou du renforcement de gatekeepers (plateformes, associations et collectifs professionnels, festivals et formations) que sur celle des conditions dans lesquelles il est possible en France aujourd'hui de faire et de gagner sa vie en tant que producteur ou créateur de jeu vidéo.
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Cours magistraux

le (1h30m18s)

B. Weiss - Horocycle dynamics (Part 1)

A major challenge in dynamics on moduli spaces is to understand the behavior of the horocycle flow. We will motivate this problem and discuss what is known and what is not known about it, focusing on the genus 2 case. Specific topics to be covered include:* SL_2(R) orbit closures and invariant measures in genus 2.* Quantitative nondivergence.* The structure of minimal sets.* Rel and real-rel, and their interaction with the horocycle flow* Horizontal data diagrams and other invariants for horocycle invariant measures.* Classification of measures and orbit-closures in the eigenform loci.* Recent and not-so-recent examples of unexpected measures and orbit-closures.
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Conférences

le (1h38s)

A. Lenzhen - Limit sets of Teichmuller geodesic rays in the Thurston boundary of Teichmuller space

H. Masur showed in the early 80s that almost every Teichmuller ray converges to a unique point in PMF. It is also known since a while that there are rays that have more than one accumulation point in the boundary.  I will give an overview of what is understood so far about the limit sets of Teichmuller rays, mentioning some recent progress. For example, I will mention recent joint work with K. Rafi and B. Modami where we give a construction of a ray whose limit set in PMF is a d-dimensional simplex.
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