Institut de Mathématiques de Marseille, UMR 7373




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11 septembre 2017: 1 événement

Séminaire

  • Séminaire Géométrie, Dynamique et Topologie (GDT)

    Lundi 11 septembre 14:00-15:00 - Natalia VIANA - I2M, Marseille

    Branched covering over the sphere

    Résumé : A branched covering of degree d over the sphere determines a finite collection D of partitions of d, called the branch datum. The converse of this assertion is not true. In 1984, A. Edmonds, R. Kulkarni and R. Stong exhibit, for any non-prime integer d, an exceptional collection, i.e. a collection of partitions satisfying the necessary conditions but that is not realizable as a branch datum of any branched covering over S^2.
    This realization problem is still open. It was completely solved just for collections involving a "short" partition like :
    1. [d], by R. Thom in 1965, via complex polynomials ;
    2. [d-1,1], by A. Edmonds, R. Kulkarni and R. Stong in 1984, via permutation groups ;
    3. [d-2,2], by E. Pervova and C. Petronio in 2008, via minimal checker-board graphs.
    For other collections are known, at most, partial results.
    In this talk, I would like to introduce the problem and some of the techniques used to study it.

    Lieu : CMI, salle de séminaire R164 (1er étage) - I2M - Château-Gombert
    39 rue Frédéric Joliot-Curie
    13453 Marseille cedex 13

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En savoir plus : Séminaire Géométrie, Dynamique et Topologie (GDT)

11 septembre 2017: 1 événement

groupe de travail

  • Agenda ERC IChaos

    Du 5 au 25 septembre - Alexander BUFETOV

    Scientific collaboration with Andrey DYMOV

    Lieu : Stecklov Math. Institute of RAS - Moscou

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En savoir plus : Agenda ERC IChaos