Institut de Mathématiques de Toulouse

Les événements de la journée


5 événements


  • Séminaire MIP

    Mardi 15 mai 09:45-10:45 - Tony Lelièvre - CERMICS, l'Ecole des Ponts ParisTech

    Metastability : a journey from stochastic processes to semiclassical analysis

    Résumé : A stochastic process is metastable if it stays for a very long period of time in a region of the phase space (called a metastable region) before going to another metastable region, where it again remains trapped. Such processes naturally appear in many applications, metastability being related to a two time scale mechanism : the small time scale corresponds to the vibration period within the metastable regions and the large time scale is associated with the transitions between metastable states. For example, in molecular dynamics, the metastable regions are typically associated with the atomic conformations of a molecule (or an ensemble of molecules), and one is actually interested in simulating and studying the transitions between these conformations.
    In this talk, I will explain how the exit events from a metastable state can be studied using an eigenvalue problem for a differential operator. This point of view is useful to build very efficient algorithms to simulate metastable stochastic processes (using in particular parallel architectures). It also gives a new way to prove the Eyring-Kramers laws and to justify the parametrization of an underlying Markov chain (Markov state model), using techniques form semiclassical analysis.
    Reference : https://arxiv.org/abs/1706.08728

    Lieu : Amphi L. Schwartz

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  • Séminaire de Probabilités

    Mardi 15 mai 09:45-10:45 - Tony Lelievre - ENPC

    Metastability : a journey from stochastic processes to semiclassical analysis

    Résumé : A stochastic process is metastable if it stays for a very long period of time in a region of the phase space (called a metastable region) before going to another metastable region, where it again remains trapped. Such processes naturally appear in many applications, metastability being related to a two time scale mechanism : the small time scale corresponds to the vibration period within the metastable regions and the large time scale is associated with the transitions between metastable states. For example, in molecular dynamics, the metastable regions are typically associated with the atomic conformations of a molecule (or an ensemble of molecules), and one is actually interested in simulating and studying the transitions between these conformations.
    In this talk, I will explain how the exit events from a metastable state can be studied using an eigenvalue problem for a differential operator. This point of view is useful to build very efficient algorithms to simulate metastable stochastic processes (using in particular parallel architectures). It also gives a new way to prove the Eyring-Kramers laws and to justify the parametrization of an underlying Markov chain (Markov state model), using techniques form semiclassical analysis.
    Reference : https://arxiv.org/abs/1706.08728
    Seminaire commun avec MIP

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  • Séminaire de Statistique

    Mardi 15 mai 11:00-12:00 - Pedro Alvarez - Universidad de Valladolid

    Trajectory clustering based on directional functional data : a case study

    Résumé : This talk is based on the work we are carrying out in the framework of a
    research contract with Boeing Research and Technology Europe. The main goal of
    this research contract is to build a prototype of bigdata platform designed to
    improve flight efficiency based on the trajectory flown. In this context, and for
    different reasons, it is interesting to detect the main modes of movement
    between two points (origin and destination airports), i.e, to look for
    homogeneous groups of trajectories and choose within each of these groups a
    trajectory that is a good representative of the way of moving that describes
    the trajectories of that group.
    First, I will briefly describe the project and then, I will describe and
    compare several alternative methods to perform trajectory clustering when one
    of the magnitudes used to characterize trajectories is the aerodynamic
    bearing, which is naturally a functional and directional data.

    Lieu : Salle 106, Bat 1R1

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  • Homotopie en Géométrie Algébrique

    Mardi 15 mai 14:00-15:00 - Grégory Ginot - IMJ, Paris 13

    Limite N large de la théorie de Chern-Simons et quantification de la topologie des cordes.

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  • Homotopie en Géométrie Algébrique

    Mardi 15 mai 15:30-16:30 - J. Tapia - IMT

    L’infinie-catégories des spèctres

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