Amitsur Algebra

  • 2016 Jun 16

    Amitsur Algebra: Gili Golan, "The generation problem in Thompson group F"

    12:00pm to 1:15pm

    Location: 

    Manchester Building (room 209), Jerusalem, Israel
    We show that the generation problem in Thompson group F is decidable, i.e., there is an algorithm which decides if a finite set of elements of F generates the whole F. The algorithm makes use of the Stallings 2-core of subgroups of F, which can be defined in an analogue way to the Stallings core of subgroups of a free group. An application of the algorithm shows that F is a cyclic extension of a group K which has a maximal elementary amenable subgroup B. The group B is a copy of a subgroup of F constructed by Brin.
  • 2016 Jun 09

    Joint Amitsur Algebra&NT Seminar: Shai Haran (Technion), "New foundations for geometry"

    12:00pm to 1:15pm

    Location: 

    Manchester Building (Ross 63), Jerusalem, Israel
    *** Please note the LOCATION ***
    We shall give a simple generalization of commutative rings. The
    category GR of such generalized rings contains ordinary commutative
    rings (fully, faithfully), but also the "integers" and the "residue
    field" at a real or complex place of a number field ; the "field with
    one element" F1 (the initial object of GR) ; the "Arithmetical
    Surface" (the categorical sum of the integers Z with them self). We
    shall show this geometry sees the real and complex places of a number
  • 2016 Apr 21

    Amitsur Algebra: Konstantin Golubev (HU)

    12:00pm to 1:15pm

    Location: 

    Manchester Building (room 209), Jerusalem, Israel
    Title: Spectral approach to the chromatic number of a simplicial complex
    Abstract: In this talk, we'll summarize results obtained in recent years in a pursuit for spectral bounds for the chromatic number of a simplicial complex. As the principal application, we'll show that Ramanujan complexes serve as family of explicitly constructed complexes with large girth and large chromatic number. We'll also present other results, such as a bound on the expansion and a bound on the mixing of a complex, and refer to open questions.
  • 2016 Apr 07

    Amitsur Algebra: Ayala Byron (HUJI), "Definable fields in the free group"

    12:00pm to 1:15pm

    Location: 

    Manchester Building (room 209), Jerusalem, Israel
    Abstract: In the early 2000s Sela proved that all non-abelian free groups share a common first-order theory. Together with R. Sklinos, we use tools developed in his work to show that no infinite field is definable in this theory. In this talk we will survey the line of proof for a formal solution theorem for a simple sort of definable sets, that have a structure of a hyperbolic tower, and use it to characterize definable sets that do not carry a definable structure of an abelian group.
  • 2015 Dec 24

    Amitsur Algebra: Michael Larsen (Indiana U)

    12:00pm to 1:15pm

    Location: 

    Manchester Building (room 209), Jerusalem, Israel
    Title: Character values on compact simple Lie groups
    Abstract: This work is part of a joint project with Aner and others to find upper bounds for values of irreducible characters in two related settings: compact simple Lie groups and finite groups of Lie type. I will discuss the first case, presenting bounds of the form
    $$|\chi(g)| = O(\chi(1)^\alpha),$$
  • 2015 Dec 03

    Amitsur Algebra: Boris Plotkin (Hebrew U)

    12:00pm to 1:15pm

    Location: 

    Manchester Building (room 209), Jerusalem, Israel
    Title: Algebraic Geometry in an arbitrary variety of algebras and Algebraic Logic
    Abstract: I will speak about a system of notions which lead to interesting new problems for groups and algebras as well as to reinterpretation of some old ones.

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