Groupe de Travail en Combinatoire Arithmétique 2011-2013
L'objectif de ce groupe de travail est de traiter des articles récents ainsi que des techniques classiques en combinatoire arithmétique. Le groupe est ouvert à toute personne interéssé. Si vous souhaitez recevoir les annonces par mail, merci de m'envoyer un bref message.
Les exposés ont lieu à l'Institut Henri Poincaré, à 16h sauf avis contraire.
Aller à la prochaine séance.
| Sujet: |
A non standard approach to higher-order Fourier analysis |
| Résumé: |
We show how to use non-standard measure theory and topology to approach various problems on Gowers norms. |
| Orateur: |
Balazs Szegedy |
| Lieu: |
IHP Salle 421 |
| Heure: |
16h |
le mercredi, 24 avril 2013
| Sujet: |
Norm convergence of nonconventional ergodic averages |
| Résumé: |
Consider a group of measure preserving transformations acting on a probability space. The limiting behavior of the nonconventional ergodic averages associated with this action has been the subject of much attention since the work of Furstenberg on Szemerédi's theorem. We will discuss this problem, and how to establish the convergence of these averages whenever the group is nilpotent.
The speaker promises the talk will be accesible. |
| Orateur: |
Miguel Walsh |
| Lieu: |
IHP Salle 314 |
| Heure: |
16h |
le mercredi, 17 avril 2013
le mercredi, 13 mars 2013
| Sujet: |
Cubes de Host-Kra et nilespaces |
| Résumé: |
Standard cubes (or parallelepipeds) on abelian groups are useful objects
in arithmetic combinatorics, involved for instance in the definition of
the Gowers norms. Host-Kra cubes on a filtered group are very natural
generalizations of standard cubes, and have come to play an important role
in the subject. We will discuss these objects, proving their main
properties, in particular the fact that they constitute central examples
of a nilspace structure, a notion developed recently by Camarena and
Szegedy.
Despite the language of the abstract, the talk will be in French! |
| Orateur: |
Pablo Candela |
| Lieu: |
IHP Salle 421 |
| Heure: |
16h |
Le mercredi, 6 mars 2013 je serai à Bristol.
le mercredi, 27 fevrier 2013
| Sujet: |
Infinite Sidon sequences (times three) |
| Résumé: |
The construction of (dense) infinite Sidon sequences had played an important role in the development of additive combinatorics. I will survey some past results, and explain in a more detailed way a very recent construction by Cilleruelo of a (dense) Sidon sequence which clarifies the best kwown result due to Ruzsa.
|
| Source: |
J. Cilleruelo: Infinite Sidon sequences
I.Z. Ruzsa: An infinite Sidon sequence
M. Ajtai, J. Komlós, and E. Szemerédi: A dense infinite Sidon sequence |
| Orateur: |
Juanjo Rué |
| Lieu: |
IHP Salle 421 |
| Heure: |
16h |
Le jeudi, 21 fevrier 2013 le séminaire CAESAR a lieu à Jussieu.
le mercredi, 13 fevrier 2013
Le mercredi, 30 janvier 2013 je serai a Cambridge.
Le jeudi, 24 janvier 2013 le séminaire CAESAR a lieu à l'Ecole polytechnique.
le mercredi, 16 janvier 2013
| Sujet: |
The Sylvester-Gallai theorem and the Dirac-Motzkin conjecture |
| Résumé: |
The Sylvester-Gallai theorem states that given a set P of n points in the plane, not all on a line, there must be a line containing precisely two points of P. The Dirac-Motzkin conjecture states that there must be at least n/2 such lines for large n, and was recently solved by Green and Tao. |
| Source: |
B. Green and T. Tao: On sets defining few ordinary lines |
| Orateur: |
Julia Wolf |
| Lieu: |
IHP Salle 421 |
| Heure: |
16h |
le mercredi, 14 mars 2012
le mercredi, 29 février 2012
le mercredi, 15 février 2012
le jeudi, 2 février 2012
le mercredi, 18 janvier 2012
le jeudi, 8 décembre 2011
le mardi, 22 novembre 2011
le jeudi, 10 novembre 2011
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