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Vorträge

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Vorträge 2017

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9 Einträge gefunden

  • Mai
  • 11. Mai
    17:00 - 18:00
    Ort: 48-436
    Algebra, Geometrie und Computer Algebra

    Andreas Bächle, University Brussels: Rationality of groups and centers of integral group rings

    A finite group is called rational if all entries of its character table are rational integers. Being rational has significant implications for the structure of the group, e.g. it is a classical result of R. Gow that the only primes dividing the order of such a group are 2, 3 and 5, if the group is solvable. The concept of rationality was generalized in 2010 by D. Chillag and S. Dolfi by introducing the term (inverse) semi-rational group. It turned out that being an inverse semi-rational group has quite some impact in the study of integral group rings. We will discuss this connection and recent results.

  • 04. Mai
    17:00 - 18:00
    Ort: 48-436
    Algebra, Geometrie und Computer Algebra

    Emil Norton, MPI Bonn: The sl_∞-crystal combinatorics of higher level Fock spaces

  • April
  • 27. April
    17:00 - 18:00
    Ort: 48-436
    Algebra, Geometry and Computer Algebra

    Kivanv Ersoy, TU Kaiserslautern: Locally finite groups with small centralizers

    In this talk we will present recent results about fixed points of automorphisms in locally finite groups. Let pbe a prime and  G a locally fi nite group containing an elementary abelian p-subgroup A of rank at least 3 such that CG (A) is Chernikov and CG (a) involves no infi nite simple groups for any a ∈ A#. We show that G is almost locally soluble. To prove this result, we first give a characterization of PSLp (k). Theorem. [1] An infi nite simple locally fi nite group G admits an elementary abelian p-group of automorphisms A such that CG (A) is Chernikov and CG (a) involves no in finite simple groups for any a ∈ A# if and only if G is isomorphic to PSLp (k) for some locally finite field k of characteristic diff erent from p and A  has order <nobr> p2. This is a joint work with Mahmut Kuzucuoglu and Pavel Shumyatsky.
    [1] Ersoy, K., Kuzucuoglu, M., Shumyatsky, P., Locally finite groups and their subgroups with small centralizers, J. Algebra, Vol. 481, 1 July 2017, p.1-11. ρ

  • März
  • 08. März
    17:00 - 18:00
    Ort: 48-436
    AG Algebra, Geometrie und Computer Algebra

    Michael Geline, Northern Illinois University: Some quantitative and qualitative aspects of Knörr lattices

    These lattices are the <nobr></nobr> p-adic representations of finite groups whose invertible endomorphisms can be distinguished by the trace function. They include the absolutely irreducible lattices as well as the indecomposable lattices of rank not divisible by p. Knörr introduced them in a 1988 paper in connection with Brauer's height zero conjecture. They are now known also to be connected with Alperin's weight conjecture. I will explain this in the talk, and, time permitting, also give a quantitative result: Knörr lattices for the elementary abelian group of order 8, over an dvr unramified over the 2-adics, do not exist.

  • Februar
  • 23. Februar
    16:00 - 17:00
    Ort: 48-436
    AG Algebra, Geometrie und Computer Algebra

    Prof. Dr. Eugenii Shustin, Tel Aviv University; Real morsifications of plane curve singularities.

    A real morsification of a real plane curve singularity is a real deformation with the maximal possible number of hyperbolic nodes (i.e., equivalent to x2-y2=0 over R). We prove that any real plane curve singularity admits a real morsification. This was known before only in the case of all local branches being real (A'Campo, Gussein-Zade). We also discuss a relation between real morsifications and the topology of singularities and extend to arbitrary real morsifications the Balke-Kaenders theorem stating that the A'Campo--Gussein-Zade diagram associated to the morsification uniquely determines the real topological type of the initial curve singularity. Joint work with Piter Leviant.

  • 09. Februar
    17:00 - 18:00
    Ort: 48-436
    AG Algebra, Geometrie und Computer Algebra

    Charles Eaton, University of Manchester: Loewy length of blocks

    I will give a brief survey on results and conjectures about the Loewy length of a block of a finite group. This includes work with Michael Livesey giving precise upper and lower bounds for 2-blocks with abelian defect groups.

  • 06. Februar
    15:30 - 17:00
    Ort: 48-438
    AG Algebra, Geometrie und Computer Algebra

    Magdalena Boos, Ruhr-Universität Bochum: Using quiver representations to prove finiteness criteria

  • Januar
  • 26. Januar
    16:00 - 17:00
    Ort: 48-436
    AG Algebra, Geometrie und Computer Algebra

    Prof. Dr. Alexander Tikhomirov, HSE Moscow, z.Z. MPIM Bonn: On the moduli spaces of stable rank two coherent sheaves on projecti

    Vortrag zum jetzigen Kenntnisstand über Modulräume
    von Vektorbündeln und Garben auf dem projektiven Raum.

  • 19. Januar
    17:00 - 18:00
    Ort: 48-436
    AG Algebra, Geometrie und Computer Algebra

    Iris Köster, Universität Stuttgart: Sylow Numbers in Character Tables and Integral Group Rings

    The Sylow p-number of a finite group is defined as the number of Sylow p-subgroups of the given group. In this talk we want to consider a question of G. Navarro whether character tables determine the Sylow numbers of the underlying group. In the second part of the talk we analyze the question whether the integral group rings determines the Sylow numbers.