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Accueil > Agenda scientifique

31 janvier 2023: 2 événements

  • Planning des séminaires 2022-2023

    Mardi 31 janvier 13:30-14:30 - Estelle Medous - Toulouse School of Economics, Univ Toulouse 1, LMB, La Poste

    Optimality of the double Generalized Weight Share Method and alternatives

    Résumé : In probabilistic surveys, when it is not possible to draw a sample from the target population, sampling can be done indirectly through a frame population related to the target population. Estimation of the parameters of interest is achieved using the Generalized Weight Share Method (GWSM). Under some conditions, this method can be used to minimize the variance of the resulting estimator. However, it may require to observe a large number of links. To reduce observation time and cost, an intermediate population and double indirect sampling can be introduced. Estimation is then performed by using a double GWSM. This method is easier to apply than the GWSM but deteriorates the precision of the resulting estimator. In this presentation, we will show that, under conditions, the variance of the double GWSM estimator can be minimized such that no precision is lost compared to the GWSM while maintaining the easier implementation of the double GWSM. Moreover, when the minimum cannot be reached, it is possible to limit the loss of precision of the double GWSM estimator compared to the GWSM.

    En savoir plus : Planning des séminaires 2022-2023
  • Séminaire d’Analyse Fonctionnelle

    Mardi 31 janvier 13:45-14:45 - Mizanur Rahaman - ENS Lyon

    Non-local games and factorizable Markov maps

    Résumé : For some games played by two cooperating but non-communicating players, the players can use entanglement as a resource to improve their outcomes beyond what is possible classically. Graph colouring game, graph homomorphism game and graph isomorphism game are a few examples of these games. Over the last few years, a remarkable progress has taken place in the theory of these non-local games. One significant aspect of this development is its connection with many challenging problems in operator algebras. In this talk, I will review the theory of these games and explain the relevant connection with operator algebras. In particular, I will introduce a new class of games which is called bisynchronous and will show a close connection between bisynchronous games and the theory of quantum permutation groups. Moreover, when the number of inputs is equal to the number of outputs, each bisynchronous correlation gives rise to a completely positive map (Markov map) which will be shown to be factorizable in the sense of Haagerup and Musat. I will also discuss a new type of factorizable maps in this talk.
    This is a joint work with Vern Paulsen and Jeremy Levick

    Lieu : 316Bbis

    En savoir plus : Séminaire d’Analyse Fonctionnelle