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Nombre de programmes trouvés : 2544
Conférences

le (1h6m42s)

MESURER LA DISTANCE DES ÉTOILES : DE L'ANTIQUITÉ AU XXIe SIÈCLE

Le sous-titre de la conférence proposée pourrait être : histoire de la découverte de notre place dans l'Univers. Dès les débuts de l'humanité les hommes se sont posés la question de la forme de la Terre, de sa dimension, de la distance à laquelle se trouvent le Soleil, la Lune, puis les planètes. Mais il faudra attendre le XVIIe siècle, après la révolution initiée par Copernic et confirmée par les observations de Galilée avec sa lunette, mettant la Terre à sa vraie place comme satellite du Soleil, pour parvenir à un bon ordre de grandeur de la distance qui ...
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Conférences

le (53m0s)

C.Fougeron - Diffusion rate for windtree models

Recent results on windtree models with polygonal obstacles have linked their diffusion rate with Lyapunov exponents in stata of quadratic differentials.  The proves of these theorems follow from the numerous symmetries of the studied examples.  In this talk I will present a general method for this purpose in a more general setting using the lattest advances on the structure of the orbit closure oftranslation surfaces and their Hodge bundle.
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Conférences

le (56m7s)

V. Gadre - Effective convergence of ergodic averages and cusp excursions of geodesics

Effective convergence of ergodic averages and cusp excursions of geodesics on moduli spacesWe survey some applications of effective convergence of ergodic averages to the analysis of cusp ex-cursions of typical geodesics on moduli spaces. This will cover Teichmuller geodesics, Weil-Peterssongeodesics and geodesics typical for harmonic measures arising from random walks on mapping class groups.
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Conférences

le (53m9s)

D. Davis - Periodic paths on the pentagon

Mathematicians have long understood periodic trajectories on the square billiard table. In the present work, we describe periodic trajectories on the regular pentagon – their geometry, symbolic dynamics, and  group  structure.   Some  of  the  periodic  trajectories  exhibit  a  surprising  "dense  but  not  equidistributed" behavior.  I will show pictures of periodic trajectories, which are very beautiful.  This is joint work with Samuel Lelièvre and Barak Weiss.
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Conférences

le (57m17s)

R. Santharoubane - Quantum representations of surface groups

I will show how we can produce exotic representations of surface groups from the Witten-Reshetikhin-Turaev TQFT. These representations have infinite images and give points on character varieties that are fixed by the action of the mapping. Moreover we can approximate these representations by representations into finite groups in order to build exotic regular finite covers of surfaces. These covers have the following property: the integral homology is not generated by pullbacks of simple closed curves on the base. This is joint work with Thomas Koberda.
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Conférences

le (54m22s)

I. Pasquinelli - Deligne-Mostow lattices and cone metrics on the sphere

Finding lattices in PU(n,1) has been one of the major challenges of the last decades.  One way of constructing a lattice is to give a fundamental domain for its action on the complex hyperbolic space.One approach, successful for some lattices, consists of seeing the complex hyperbolic space as the configuration space of cone metrics on the sphere and of studying the action of some maps exchanging the cone points with same cone angle.In this talk we will see how this construction can be used to build fundamental polyhedra for all Deligne-Mostow lattices in PU(2,1).
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Conférences

le (47m25s)

Knowledge transfer and human-machine collaboration for training object class detector

Object class detection is a central area of computer vision. It requires recognizing and localizing all objects of predefined set of classes in an image. Detectors are usually trained under full supervision, which requires manually drawing object bounding-boxes in a large number of training images. This is tedious and very time consuming.  In this talk I will present two recent techniques for reducing this effort. In the first part I will explore a knowledge transfer scenario: training object detectors for target classes with only image-level labels, helped by a set of source classes with bounding-box annotations. I will present a unified ...
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Conférences

le (58m5s)

P. Apisa - Marked points in genus two and beyond

In the principal stratum in genus two, McMullen observed that something odd happens - there is only one nonarithmetic Teichmuller curve - the one generated by the decagon.  This strange phenomenon begets another - a primitive translation surface in genus two admits a periodic point that is not a Weierstrass point or zero only if it belongs to the golden eigenform locus. In this talk, we will explain how to leverage results of Mirzakhani-Wright to study the orbit closures of translation surfaces with marked points and sketch a proof of the previously mentioned result in genus two. We will also ...
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Conférences

le (1h3m20s)

S.Schleimer - An introduction to veering triangulations

Singular euclidean structures on surfaces are a key tool in the study of the mapping class group,of Teichmüller space, and of kleinian three-manifolds.  François Guéritaud, while studying work ofIan Agol, gave a powerful technique for turning a singular euclidean structure (on a surface) into atriangulation (of a three-manifold).  We will give an exposition of some of this work from the pointof  view  of  Delaunay  triangulations  for  theL∞-metric.   We  will  review  the  definitions  in  a  relaxedfashion,  discuss  the  technique,  and  then  present  applications  to  the  study  of  strata  in  the  space  ofsingular euclidean structures. If time permits, we will also discuss ...
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