Amitsur Algebra

  • 2020 Mar 26

    POSTPONED! Be'eri Greenfeld (BIU): How do algebras grow?

    12:00pm to 1:00pm

    Location: 

    Seminar room 209, Manchester Building, Jerusalem, Israel.
    How do algebras grow?




    The question of `how do algebras grow?', or, which functions can be realized as growth functions of algebras (associative/Lie, or algebras having certain additional algebraic properties) is a major problem in the meeting point of several mathematical fields including algebra, combinatorics, symbolic dynamics and more.


  • 2020 Jan 16

    Lev Glebsky (UASLP): Residually finite by residually finite extensions are weakly sofic

    12:00pm to 1:00pm

    Location: 

    Manchester Building, Room 209
    January 16, 12:00-13:00, Seminar room 209, Manchester building.

    Abstract: I plan to show a proof of the statement  "residually-finite-by-residually-finite extensions are weakly sofic". The proof is based on characterization of weakly sofic groups 
    by solvability of equations over groups. It looks different from other proofs of soficity and weak soficity. I plan to discuss relations of equations on and over groups with soficity in some details.

  • 2020 Jan 02

    Tamar Bar-On (BIU): Profinite completion of free profinite groups

    12:00pm to 1:00pm

    Location: 

    Seminar room 209, Manchester Building, Givat ram

    Abstract: The profinite completion of a free profinite group on an infinite set of generators is a profinite group of greater rank. However, it is still unknown whether it is a free profinite group as well. I am going to present some partial results regarding this question.
  • 2018 Jun 27

    Amitsur Symposium: Yael Algom-Kfir - "The metric completion of an asymmetric metric space"

    4:30pm to 5:30pm

    Location: 

    Manchester House, Lecture Hall 2
    The Teichmuller space with the Thurston metric and Outer Space with the Lipschitz metric are two examples of spaces with an asymmetric metric i.e. d(x,y)
    eq d(y,x). The latter case is also incomplete: There exist Cauchy sequences that do not have a limit. We develop the theory of the completion of an asymmetric space and give lots of examples. Time permitting we will describe the case of Outer Space.
  • 2018 Jun 27

    Amitsur Symposium: Tsachik Gelander - "Local rigidity of uniform lattices"

    3:00pm to 4:00pm

    Location: 

    Manchester House, Lecture Hall 2
    We establish topological local rigidity for uniform lattices in compactly generated groups, extending the result of Weil from the realm of Lie groups. We generalize the classical local rigidity theorem of Selberg, Calabi and Weil to irreducible uniform lattices in Isom(X) where X is a proper CAT(0) space with no Euclidian factors, not isometric to the hyperbolic plane. We deduce an analog of Wang’s finiteness theorem for certain non-positively curved metric spaces.
    This is a joint work with Arie Levit.
  • 2018 Jun 27

    Amitsur Symposium: Chloe Perin - "Forking independence in the free group"

    2:00pm to 3:00pm

    Location: 

    Manchester House, Lecture Hall 2
    Model theorists define, in structures whose first-order theory is "stable" (i.e. suitably nice), a notion of independence between elements. This notion coincides for example with linear independence when the structure considered is a vector space, and with algebraic independence when it is an algebraically closed field. Sela showed that the theory of the free group is stable. In a joint work with Rizos Sklinos, we give an interpretation of this model theoretic notion of independence in the free group using Grushko and JSJ decompositions.
  • 2018 Jun 27

    Amitsur Symposium: Amiram Braun - "The polynomial question in modular invariant theory, old and new"

    11:30am to 12:30pm

    Location: 

    Manchester House, Lecture Hall 2
    Let G be a finite group, V a finite dimensional G- module over a field F, and S(V) the symmetric algebra of V. The above problem seeks to determine when is the ring of invariants S(V)^G , a polynomial ring. In the non-modular case (i.e. char(F) being prime to order(G)), this was settled in the Shephard-Todd-Chevalley theorem. The modular case (i.e. char(F) divides order (G) ), is still wide open. I shall discuss some older results due to Serre, Nakajima , Kemper-Malle and explain some new results, mostly in dimension 3.

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