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Nombre de programmes trouvés : 757
Conférences

le (1h9m28s)

Numbers, computers and dynamical systems

A discrete dynamical system is defined as a set of states on which a transformation acts, considered as an evolution rule. The terminology discrete refers to the time that is discretized: at time n corresponds the nth iteration of this transformation. Dynamical systems are widely studied, for their modelling as well as for their computation power. We will focus here more specifically on trajectories of chaotic dynamical system from a computer science viewpoint (finite or periodic trajectories). A classical example is provided by the ...
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Entretiens

le (23m55s)

De l’idée de race - Entretien avec Hervé Le Bras

De l'idée de race   Entretien avec Hervé Le Bras Dans cet entretien, le démographe et historien Hervé LeBras évoque l’apparition de la notion de « races humaines » d’abord en biologie, puis en sciences humaines et sociales. Au 18ème siècle, le naturaliste suédois Carl Von Linné propose une classification des espèces encore utilisée de nos jours en zoologie. Cette conception servira de base à des classifications des êtres humains eux-mêmes. La théorie darwinienne de l’évolution des espèces, qui en elle-même n’est nullement raciste ...
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Conférences

le (32m58s)

B. Berndtsson - The curvature of (higher) direct images

I will first discuss some earlier work on the curvature of direct images of adjoint line bundles under a smooth proper fibration, or more generally a surjective map and (maybe) some of its applications. Then I will present a general formula for the curvature of higher direct images. This contains as a special case (part of) the earlier work, and also generalizes results of Siu and Schumacher. (The second part is based on joint work with Mihai Paun and Xu Wang.)
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Conférences

le (50m52s)

D. Brotbek - On the hyperbolicity of general hypersurfaces

A smooth projective variety over the complex numbers is said to be (Brody) hyperbolic if it doesn’t contain any entire curve. Kobayashi conjectured in the 70’s that general hypersurfaces of sufficiently large degree in PN are hyperbolic. This conjecture was only recently proved by Siu. The purpose of this talk is to present a new proof of this conjecture. The main idea of the proof, based on the theory of jet differential equations, is to establish that a stronger property, open in the Zariski topology, ...
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Conférences

le (52m41s)

F. Campana - Birational stability of the orbifold cotangent bundle

We show that a foliation on a projective complex manifold is algebraic with rationally connected (closure of) leaves exactly when its minimal slope with respect to some movable class is positive. This extends and strengthens former classical results by Y. Miyaoka and Bogomolov-McQuillan. Applications to foliations, hyperbolicity (a converse to a result of JP. Demailly) and moduli will be mentioned.This is a joint work with Mihai Paun, partly based on a former joint work with T.
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Conférences

le (45m22s)

R. Berman - Canonical metrics, random point processes and tropicalization

In this talk I will present a survey of the connections between canonical metrics and random point processes on a complex algebraic variety X. When the variety X has positive Kodaira dimension, this leads to a probabilistic construction of the canonical metric on X introduced by Tsuji and Song-Tian (coinciding with the Kähler-Einstien metric when X is of general type). In the opposite setting of Fano varieties this suggests a probalistic analog of the Yau-Tian-Donaldson conjecture. The probabilistic version of the ...
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Conférences

le (1h3s)

T. Darvas - Complex Monge-Ampère equations with prescribed singularity type

Given a Kahler manifold (X, ω), finding smooth solutions to the equation (ø +i∂̄∂u)n=føn goes back to Yau’s solution of the Calabi conjecture in the seventies. In joint work with E. Di Nezza and C.H. Lu, we proposed to solve this same equation with the added constraint that u ∈ PSH(X, ω) has prescribed singularity type. As it turns out, this problem is well posed only ...
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Conférences

le (51m42s)

S. Donaldson - Boundary value problems for $G_2$ structures

In the lecture we consider the existence of G2 structures on 7-manifolds with boundary, with prescribed data on the boundary. In the first part we will review general background and theory, including Hitchin’s variational approach. We will then discuss in more detail reductions of the problem in the presence of symmetry and in ”adiabatic limits”, and connections with real and complex Monge-Ampère equations.
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