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Documents : Post-edited  Conférences Vidéo Chapitrées | enregistrements trouvés : 200

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Post-edited  Interview at CIRM: Endre Szemerédi Szemerédi, Endre (Personne interviewée) | CIRM (Editeur )

Endre Szemerédi (born August 21, 1940) is a Hungarian-American mathematician, working in the field of combinatorics and theoretical computer science. He has been the State of New Jersey Professor of computer science at Rutgers University since 1986. Szemerédi has won prizes in mathematics and science, including the Abel Prize in 2012. He has made a number of discoveries in combinatorics and computer science, including Szemerédi's theorem, the Szemerédi regularity lemma, the Erdös-Szemeredi theorem, the Hajnal-Szemerédi theorem and the Szemerédi-Trotter theorem.
Endre Szemerédi (born August 21, 1940) is a Hungarian-American mathematician, working in the field of combinatorics and theoretical computer science. He has been the State of New Jersey Professor of computer science at Rutgers University since 1986. Szemerédi has won prizes in mathematics and science, including the Abel Prize in 2012. He has made a number of discoveries in combinatorics and computer science, including Szemerédi's theorem, the ...

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Post-edited  Interview au CIRM : Jean-Pierre Serre avec Jean-Louis Colliot-Thélène Serre, Jean-Pierre (Personne interviewée) ; Colliot-Thélène, Jean-Louis (Personne interviewée) | CIRM (Editeur )

Jean-Pierre Serre est un mathématicien français, plus jeune Médaille Fields en 1954, il fut également le premier lauréat du Prix Abel en 2003.

Jean-Louis Colliot-Thélène est un mathématicien français, Directeur de recherches à l'Université Paris-Sud, il étudie principalement la théorie des nombres et la géométrie algébrique.

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Post-edited  Persistence modules and Hamiltonian diffeomorphisms - Part 1 Polterovich, Leonid (Auteur de la Conférence) | CIRM (Editeur )

Theory of persistence modules is a rapidly developing field lying on the borderline between algebra, geometry and topology. It provides a very useful viewpoint at Morse theory, and at the same time is one of the cornerstones of topological data analysis. In the course I'll review foundations of this theory and focus on its applications to symplectic topology. In parts, the course is based on a recent work with Egor Shelukhin arXiv:1412.8277

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Post-edited  A universal hypercyclic representation Glasner, Eli (Auteur de la Conférence) | CIRM (Editeur )

For any countable group, and also for any locally compact second countable, compactly generated topological group, $G$, there exists a "universal" hypercyclic representation on a Hilbert space, in the sense that it simultaneously models every possible ergodic probability measure preserving free action of $G$. I will discuss the original proof of this theorem (a joint work with Benjy Weiss) and then, at the end of the talk, say some words about the development of this idea and its applications as expounded in a subsequent work of Sophie Grivaux.
For any countable group, and also for any locally compact second countable, compactly generated topological group, $G$, there exists a "universal" hypercyclic representation on a Hilbert space, in the sense that it simultaneously models every possible ergodic probability measure preserving free action of $G$. I will discuss the original proof of this theorem (a joint work with Benjy Weiss) and then, at the end of the talk, say some words about ...

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Post-edited  Terminologie des données encyclopédiques et politique de repérage Guilbaud, Alexandre (Auteur de la Conférence) ; Leca-Tsiomis, Marie (Auteur de la Conférence) ; Passeron, Irène (Auteur de la Conférence) ; Cernuschi, Alain (Auteur de la Conférence) | CIRM (Editeur )

La richesse du contenu de l'Encyclopédie nécessite la définition d'un protocole de présentation et d'éclairage critique se déclinant à plusieurs échelles : aux textes de présentations généraux (de tel volume, de tel article ou ensemble d'articles) et notes ponctuelles classiques s'ajouteront à la fois la possibilité de mettre en valeur les nombreux éléments caractéristiques constitutifs du texte encyclopédique (les titres des articles, les désignants, les renvois vers d'autres articles, les signatures des encyclopédistes, les mentions de leurs sources, etc.) et la possibilité d'y articuler finement les annotations permettant d'en éclairer les intérêts et les enjeux. La mise en place d'un tel apparat critique requiert la définition préalable des éléments du texte encyclopédique que nous souhaitons repérer, et des liens qu'ils entretiennent entre eux. Cette politique éditoriale sera ici exposée dans le détail, avec la terminologie qui y est associée.
La richesse du contenu de l'Encyclopédie nécessite la définition d'un protocole de présentation et d'éclairage critique se déclinant à plusieurs échelles : aux textes de présentations généraux (de tel volume, de tel article ou ensemble d'articles) et notes ponctuelles classiques s'ajouteront à la fois la possibilité de mettre en valeur les nombreux éléments caractéristiques constitutifs du texte encyclopédique (les titres des articles, les ...

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Post-edited  Interview at CIRM: François Lalonde Lalonde, François (Personne interviewée) | CIRM (Editeur )

François Lalonde, Professor at the Mathematics and Statistics Department of the Université de Montréal, was named Director of the Centre de recherches mathématiques (CRM) on September 14, 2004. The CRM is the first institute of research in mathematical sciences founded in Canada in 1969.
A member of the Royal Society of Canada since 1997, François Lalonde's research is mainly in the field of Symplectic geometry and topology. From 1996 to 2000, he directed the Institut des sciences mathématiques (ISM), a consortium of six Québec universities (Montréal, McGill, UQAM, Concordia, Laval and Sherbrooke). In this capacity, he developed the Institute by putting in place measures furthering the place of Montréal, and Québec as a whole, as a North American centre of excellence in mathematical research and training.
Mr. Lalonde was also the Founder and Director of the Centre interuniversitaire de recherche en géométrie différentielle et en topologie (CIRGET) which gathers together the best geometers and topologists from UQAM, McGill, Montreal and Concordia universities.
A mathematician and physicist by training, François Lalonde holds a Doctorat d’Etat (1985) from Orsay Center in Paris, in the field of differential topology. He was a Killam Research Fellowship recipient in 2000-2002 and holds a Canada Research Chair in the field of Symplectic Geometry and Topology. He is member of the editorial committees of the Canadian Journal of Mathematics and of the Canadian Bulletin of Mathematics. Member of the scientific committee of the First Canada-France congress in 2004 and plenary speaker at the First Canada-China congress in 1999, his works in collaboration with Dusa McDuff were presented in her plenary address at the ICM in 1998. He is an invited speaker at the ICM 2006.
CIRM - Chaire Jean-Morlet 2015 - Aix-Marseille Université
François Lalonde, Professor at the Mathematics and Statistics Department of the Université de Montréal, was named Director of the Centre de recherches mathématiques (CRM) on September 14, 2004. The CRM is the first institute of research in mathematical sciences founded in Canada in 1969.
A member of the Royal Society of Canada since 1997, François Lalonde's research is mainly in the field of Symplectic geometry and topology. From 1996 to 2000, ...

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Post-edited  Galois codes for arithmetic and geometry via the power of valuation theory Koenigsmann, Jochen (Auteur de la Conférence) | CIRM (Editeur )

We give a survey on recent advances in Grothendiek's program of anabelian geometry to characterize arithmetic and geometric objects in Galois theoretic terms. Valuation theory plays a key role in these developments, thus confirming its well deserved place in mainstream mathematics.
The talk notes are available in the PDF file at the bottom of the page.

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Post-edited  Whitney problems and real algebraic geometry Fefferman, Charles (Auteur de la Conférence) | CIRM (Editeur )

This talk sketches connections between Whitney problems and e.g. the problem of deciding whether a given rational function on $\mathbb{R}^n$ belongs to $C^m$.

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Post-edited  On the remodeling conjecture for toric Calabi-Yau 3-orbifolds Liu, Chiu-Chu Melissa (Auteur de la Conférence) | CIRM (Editeur )

The remodeling conjecture proposed by Bouchard-Klemm-Marino-Pasquetti relates Gromov-Witten invariants of a semi-projective toric Calabi-Yau 3-orbifold to Eynard-Orantin invariants of the mirror curve of the toric Calabi-Yau 3-fold. It can be viewed as a version of all genus open-closed mirror symmetry. In this talk, I will describe results on this conjecture based on joint work with Bohan Fang and Zhengyu Zong.

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Post-edited  Cohomology and $L^2$-Betti numbers for subfactors and quasi-regular inclusions Vaes, Stefaan (Auteur de la Conférence) | CIRM (Editeur )

I present a joint work with S. Popa and D. Shlyakhtenko introducing a cohomology theory for quasi-regular inclusions of von Neumann algebras. In particular, we define $L^2$-cohomology and $L^2$-Betti numbers for such inclusions. Applying this to the symmetric enveloping inclusion of a finite index subfactor, we get a cohomology theory and a definition of $L^2$-Betti numbers for finite index subfactors, as well as for arbitrary rigid $C^*$-tensor categories. For the inclusion of a Cartan subalgebra in a $II_1$ factor, we recover Gaboriau’s $L^2$-Betti numbers for equivalence relations.
I present a joint work with S. Popa and D. Shlyakhtenko introducing a cohomology theory for quasi-regular inclusions of von Neumann algebras. In particular, we define $L^2$-cohomology and $L^2$-Betti numbers for such inclusions. Applying this to the symmetric enveloping inclusion of a finite index subfactor, we get a cohomology theory and a definition of $L^2$-Betti numbers for finite index subfactors, as well as for arbitrary rigid $C^*$-tensor ...

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Post-edited  A spectral inequality for the bi-Laplace operator Robbiano, Luc (Auteur de la Conférence) | CIRM (Editeur )

In this talk we present a inequality obtained with Jérôme Le Rousseau, for sum of eigenfunctions for bi-Laplace operator with clamped boundary condition. These boundary conditions do not allow to reduce the problem for a Laplacian with adapted boundary condition. The proof follow the strategy used for Laplacian, namely we consider a problem with an extra variable and we prove Carleman estimates for this new problem. The main difficulty is to obtain a Carleman estimate up to the boundary.
In this talk we present a inequality obtained with Jérôme Le Rousseau, for sum of eigenfunctions for bi-Laplace operator with clamped boundary condition. These boundary conditions do not allow to reduce the problem for a Laplacian with adapted boundary condition. The proof follow the strategy used for Laplacian, namely we consider a problem with an extra variable and we prove Carleman estimates for this new problem. The main difficulty is to ...

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Post-edited  La bibliothèque demain Klee, Louis (Auteur de la Conférence) | CIRM (Editeur )

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Post-edited  Stability and applications to birational and hyperkaehler geometry - Lecture 1 Bayer, Arend (Auteur de la Conférence) | CIRM (Editeur )

This lecture series will be an introduction to stability conditions on derived categories, wall-crossing, and its applications to birational geometry of moduli spaces of sheaves. I will assume a passing familiarity with derived categories.

- Introduction to stability conditions. I will start with a gentle review of aspects of derived categories. Then an informal introduction to Bridgeland’s notion of stability conditions on derived categories [2, 5, 6]. I will then proceed to explain the concept of wall-crossing, both in theory, and in examples [1, 2, 4, 6].

- Wall-crossing and birational geometry. Every moduli space of Bridgeland-stable objects comes equipped with a canonically defined nef line bundle. This systematically explains the connection between wall-crossing and birational geometry of moduli spaces. I will explain and illustrate the underlying construction [7].

- Applications : Moduli spaces of sheaves on $K3$ surfaces. I will explain how one can use the theory explained in the previous talk in order to systematically study the birational geometry of moduli spaces of sheaves, focussing on $K3$ surfaces [1, 8].
This lecture series will be an introduction to stability conditions on derived categories, wall-crossing, and its applications to birational geometry of moduli spaces of sheaves. I will assume a passing familiarity with derived categories.

- Introduction to stability conditions. I will start with a gentle review of aspects of derived categories. Then an informal introduction to Bridgeland’s notion of stability conditions on derived categories ...

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Post-edited  Victor Havin tribute : 50 years with Hardy spaces. What next... ? Nikolski, Nikolai K. (Auteur de la Conférence) | CIRM (Editeur )

Starting with a personal tribute to Victor Havin (1933-2015), I discuss a dozen achievements of Great Havin’s Analysis Seminar, as well as some challenging still unsolved problems.
The Havin publications list is available in the PDF file at the bottom of the page.

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Post-edited  Interview at CIRM: Dominique Barbolosi Barbolosi, Dominique (Personne interviewée) | CIRM (Editeur )

Dominique Barbolosi est professeur à l’Université d’Aix-Marseille. Après l’agrégation, un doctorat de mathématiques et une longue carrière de chercheur, il est devenu un spécialiste mondialement reconnu dans le domaine des applications des mathématiques à la médecine. Ses recherches actuelles concernent l'utilisation des modèles mathématiques afin d'intégrer la complexité biologique et fournir des outils algorithmiques aux médecins pour optimiser l'efficacité des traitements anticancéreux, tout en limitant leurs effets toxiques.
Dominique Barbolosi est professeur à l’Université d’Aix-Marseille. Après l’agrégation, un doctorat de mathématiques et une longue carrière de chercheur, il est devenu un spécialiste mondialement reconnu dans le domaine des applications des mathématiques à la médecine. Ses recherches actuelles concernent l'utilisation des modèles mathématiques afin d'intégrer la complexité biologique et fournir des outils algorithmiques aux médecins pour ...

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Post-edited  High energy asymptotics of the scattering matrix for Schrödinger and Dirac operators Nakamura, Shu (Auteur de la Conférence) | CIRM (Editeur )

We consider short-range perturbations of elliptic operators on $R^d$ with constant coefficients, and study the asymptotic properties of the scattering matrix as the energy tends to infinity. We give the leading terms of the symbol of the scattering matrix. The proof employs semiclassical analysis combined with a generalization of the Isozaki-Kitada theory on time-independent modifiers. We also consider scattering matrices for 2 and 3 dimensional Dirac operators. (joint work with Alexander Pushnitski (King’s College London)
We consider short-range perturbations of elliptic operators on $R^d$ with constant coefficients, and study the asymptotic properties of the scattering matrix as the energy tends to infinity. We give the leading terms of the symbol of the scattering matrix. The proof employs semiclassical analysis combined with a generalization of the Isozaki-Kitada theory on time-independent modifiers. We also consider scattering matrices for 2 and 3 dimensional ...

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Post-edited  Interview at CIRM: Sylvia Serfaty Serfaty, Sylvia (Personne interviewée) | CIRM (Editeur )

Sylvia Serfaty is a Professor at the Laboratoire Jacques-Louis Lions, Université Pierre et Marie Curie Paris 6. Sylvia Serfaty was a Global Distinguished Professor of Mathematics in the Courant Institute of Mathematical Sciences. She has been awarded a Sloan Foundation Research Fellowship and a NSF CAREER award (2003), the 2004 European Mathematical Society Prize, 2007 EURYI (European Young Investigator) award, and has been invited speaker at the International Congress of Mathematicians (2006), Plenary speaker at the European Congress of Mathematics (2012) and has recently received the IAMP Henri Poincar´e prize in 2012. Her research is focused on the study of Nonlinear Partial Differential Equations, calculus of variations and mathematical physics, in particular the Ginzburg-Landau superconductivity model. Sylvia Serfaty was the first to make a systematic and impressive asymptotic analysis for the case of large parameters in theory of the Ginzburg-Landau equation. She established precisely, with Etienne Sandier, the values of the first critical fields for nucleation of vortices in superconductors, as well as the leading and next to leading order effective energies that govern the location of these vortices and their arrangement in Abrikosov lattices In micromagnetics, her work with F. Alouges and T. Rivière breaks new ground on singularly perturbed variational problems and provides the first explanation for the internal structure of cross-tie walls.
http://www.ams.org/journals/notices/200409/people.pdf
Personal page : http://www.ann.jussieu.fr/~serfaty/
Sylvia Serfaty is a Professor at the Laboratoire Jacques-Louis Lions, Université Pierre et Marie Curie Paris 6. Sylvia Serfaty was a Global Distinguished Professor of Mathematics in the Courant Institute of Mathematical Sciences. She has been awarded a Sloan Foundation Research Fellowship and a NSF CAREER award (2003), the 2004 European Mathematical Society Prize, 2007 EURYI (European Young Investigator) award, and has been invited speaker at ...

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Post-edited  Non-backtracking spectrum of random graphs: community detection and non-regular Ramanujan graphs Massoulié, Laurent (Auteur de la Conférence) | CIRM (Editeur )

A non-backtracking walk on a graph is a directed path such that no edge is the inverse of its preceding edge. The non-backtracking matrix of a graph is indexed by its directed edges and can be used to count non-backtracking walks of a given length. It has been used recently in the context of community detection and has appeared previously in connection with the Ihara zeta function and in some generalizations of Ramanujan graphs. In this work, we study the largest eigenvalues of the non-backtracking matrix of the Erdos-Renyi random graph and of the Stochastic Block Model in the regime where the number of edges is proportional to the number of vertices. Our results confirm the "spectral redemption" conjecture that community detection can be made on the basis of the leading eigenvectors above the feasibility threshold.
A non-backtracking walk on a graph is a directed path such that no edge is the inverse of its preceding edge. The non-backtracking matrix of a graph is indexed by its directed edges and can be used to count non-backtracking walks of a given length. It has been used recently in the context of community detection and has appeared previously in connection with the Ihara zeta function and in some generalizations of Ramanujan graphs. In this work, we ...

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Post-edited  Wrapping in exact real arithmetic Müller, Norbert (Auteur de la Conférence) | CIRM (Editeur )

A serious problem common to all interval algorithms is that they suffer from wrapping effects, i.e. unnecessary growth of approximations during a computation. This is essentially connected to functional dependencies inside vectors of data computed from the same inputs. Reducing these effects is an important issue in interval arithmetic, where the most successful approach uses Taylor models.
In TTE Taylor models have not been considered explicitly, as they use would not change the induced computability, already established using ordinary interval computations. However for the viewpoint of efficiency, they lead to significant improvements.
In the talk we report on recent improvements on the iRRAM software for exact real arithmetic (ERA) based on Taylor models. The techniques discussed should also easily be applicable to other software for exact real computations as long as they also are based on interval arithmetic.
As instructive examples we consider the one-dimensional logistic map and a few further discrete dynamical systems of higher dimensions
Joint work with Franz Brauße, Trier, and Margarita Korovina, Novosibirsk.
A serious problem common to all interval algorithms is that they suffer from wrapping effects, i.e. unnecessary growth of approximations during a computation. This is essentially connected to functional dependencies inside vectors of data computed from the same inputs. Reducing these effects is an important issue in interval arithmetic, where the most successful approach uses Taylor models.
In TTE Taylor models have not been considered ...

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Post-edited  Macroscopic fluctuation theory. Lecture 1: Particle systems, scaling limits and large deviations Gabrielli, Davide (Auteur de la Conférence) | CIRM (Editeur )

In this first lecture I will introduce a class of stochastic microscopic models very useful as toy models in non equilibrium statistical mechanics. These are multi-component stochastic particle systems like the exclusion process, the zero range process and the KMP model. I will discuss their scaling limits and the corresponding large deviations principles. Problems of interest are the computation of the current flowing across a system and the understanding of the structure of the stationary non equilibrium states. I will discuss these problems in specific examples and from two different perspectives. The stochastic microscopic and combinatorial point of view and the macroscopic variational approach where the microscopic details of the models are encoded just by the transport coefficients.
In this first lecture I will introduce a class of stochastic microscopic models very useful as toy models in non equilibrium statistical mechanics. These are multi-component stochastic particle systems like the exclusion process, the zero range process and the KMP model. I will discuss their scaling limits and the corresponding large deviations principles. Problems of interest are the computation of the current flowing across a system and the ...

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