Le prochain séminaire quimpériodique aura lieu les 9 et 10 octobre prochain. Les inscriptions sont déjà ouvertes ici :
https://www.lebesgue.fr/fr/QMPoctobre2025/inscription
In this talk, I will explain how to relate the Novikov ring and microlocal sheaf theory based on the works of Tamarkin and Vaintrob. This relation has been successfully applied to the irregular Riemann-Hilbert correspondence and symplectic geometry, and recently, Scholze revealed certain potential applications of the relation in analytic geometry. Surprisingly, we notice that the almost ring theory invented by Faltings for p-adic Hodge theory plays a central role in the related construction. After that, I will explain some applications of the idea in symplectic geometry.
This talk is based on a joint work with Tatsuki Kuwagaki.
We consider a system of N Brownian particles interacting through a long-range smooth potential. It is known that "propagation of chaos" holds in the mean-field scaling. Assume indeed that the initial distribution of the particles is chaotic, i.e. that the particles are independent and identically distributed. Then, for any given time, and as N becomes large, the distribution of particles remains chaotic. Moreover, the distribution of a typical particle is given by the solution of a Vlasov-Fokker-Planck equation.
In this talk, we will investigate the creation of chaos phenomenon. Starting from an initial distribution of particles which is only exchangeable, we prove that in some weak norm, propagation of chaos holds up to an error stemming from initial correlations, exponentially damped over time. This is a joint work with Armand Bernou and Mitia Duerinckx.
In this talk, we discuss the effects of perturbations on the topology and geometry of nodal sets/zero sets of Laplace eigenfunctions. A conjecture by Payne states that the nodal set of the second Dirichlet eigenfunction on a bounded planar domain intersects the boundary at exactly two points. We will look into certain stability properties of the nodal sets and discuss some recent results concerning the conjecture. Then, utilising the stability properties, we will observe the prescription of nodal data on Riemannian surfaces, focusing on the following two aspects: the construction of eigenfunctions with a prescribed number of nodal intersections at the boundary, and the realisation of Courant-sharp eigenfunctions at arbitrarily high levels.
Applicants must have obtained a Ph.D. or equivalent degree before starting the postdoc position and should be within 3 years after their PhD defense when starting the postdoc position. The successful applicant must have strong background in one or several of the following topics related to this project: spectral theory, microlocal or semiclassical analysis, dynamical systems, probability, mathematical quantum chaos. Moreover some experience in sub-Riemannian geometry will be most appreciated. In particular, the goal of this short term position is to study an approximation scheme that is taylored to a general sub-Riemannian structure and we aim for instance at describing joint asymptotic expansions for the heat kernel. He/She will have facilities to travel and he/she will be able to interact with members of the research project throughout France.
Une conférence Symplectic Geometry and Dynamics en l'honneur de François Laudenbach est organisée au Laboratoire de mathématiques Jean Leray. Elle aura lieu du 13 au 15 octobre 2025.
Les soutenances de M2 MF ont lieu en salle des séminaires.
Programme :
9h00 - 9h35 : Ony Aubril : Representations of Crossed Modules of Finite Groups, an Approach via Categories of Modules over Hopf Algebras (encadrant: Friedrich Wagemann)
9h45 - 10h20 : Jean Mousseau : Borne fewnomiale pour la multiplicité locale (encadrant: Frédéric Bihan — absent)
10h30 - 11h05 : Célestin Kleitz : Unicité des solutions faibles aux équations de Vlasov-Poisson (encadrant: Daniel Han-Kwan)
11h15 - 11h50 : Salim Chahin : Analyse Spectrale des Opérateurs Non Bornés : Pseudo-Spectre, Semigroupes Fortement Continues et Applications à l'Oscillateur Harmonique (encadrant: Dorian Le Peutrec)
12h05 - 12h40 : Hanaë Vandanjon : Autour de la transformée de Hilbert bilinéaire (encadrante: Cristina Benea)
13h45 - 14h20 : Julies Bonafé : Local Well-Posedness of the Randomized Cauchy Problem for Supercritical non-linear Wave Equation (encadrant: Gabriel Rivière)
14h30 - 15h05 : Killian Sylvestre : FI-modules and their homology (encadrant: Geoffrey Powell)
15h15 - 15h50 : Thomas Despres : Analyse microlocale des faisceaux et noeuds Legendriens (encadrant: Stéphane Guillermou)
16h00 - 16h35 : Maël Guillon Étude d'un système de Lotka-Volterra contrôlé en dimension 3. (Peut-on jouer indéfiniment à Poule-Renard-Vipère ?) (encadrant: Jérémy Rouot — absent)
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