Colloquium

  • 2016 Dec 08

    Colloquium: Gordon Slade (UBC) "Critical phenomena in statistical mechanics"

    2:30pm to 3:30pm

    Location: 

    Manchester Building (Hall 2), Hebrew University Jerusalem
    The subject of phase transitions and critical phenomena in statistical mechanics is a rich source of interesting and difficult mathematical problems. There has been considerable success in solving such problems for systems in spatial dimension 2, or in high dimensions, but not in dimension 3. This lecture is intended to provide an introduction to recent work that employs a renormalisation group method to study spin systems and self-avoiding walk in dimension 4 (joint with Bauerschmidt and Brydges), as well as long-range versions of these models in dimensions 1,2,3 via an "epsilon expansion."
  • 2016 Dec 01

    Colloquium: Shaul Zemel (Hebrew University) "Actions of Groups on Compact Riemann Surfaces"

    2:30pm to 3:30pm

    Location: 

    Manchester Building (Hall 2), Hebrew University Jerusalem
    A compact Riemann surface gives rise to several families of vector spaces, associated to divisors on the Riemann surface. A finite group G of automorphisms acts on the spaces associated with invariant divisors, and a natural question is to characterize the resulting representations of G. We show how a very simple normalization for the invariant divisors can help in answering this question in a very direct manner, and if time permits present some applications.
  • 2016 Nov 24

    Colloquium: Dan Freed (University of Texas) "Bordism and topological phases of matter"

    2:00pm to 3:00pm

    Location: 

    Manchester Building (Hall 2), Hebrew University Jerusalem
    Topological ideas have at various times played an important role in condensed matter physics. This year's Nobel Prize recognized the origins of a particular application of great current interest: the classification of phases of a quantum mechanical system. Mathematically, we would like describe them as path components of a moduli space, but that is not rigorously defined as of now. In joint work with Mike Hopkins we apply
    stable homotopy theory (Adams spectral sequence) to compute the group of
    topological phases of "invertible" systems. We posit a continuum field
  • 2016 Nov 24

    Zabrodsky Lectures: Bordism and topological phases of matter

    Lecturer: 

    Dan Freed, University of Texas at Austin
    2:00pm

    Location: 

    Lecture Hall 2
    Topological ideas have at various times played an important role in condensed matter physics. This year's Nobel Prize recognized the origins of a particular application of great current interest: the classification of phases of a quantum mechanical system. Mathematically, we would like describe them as path components of a moduli space, but that is not rigorously defined as of now. In joint work with Mike Hopkins we apply stable homotopy theory (Adams spectral sequence) to compute the group of topological phases of "invertible" systems.
  • 2016 Nov 17

    Colloquium: Boris Zilber (Oxford) " A model-theoretic semantics of algebraic quantum mechanics"

    2:30pm to 3:30pm

    Location: 

    Manchester Building (Hall 2), Hebrew University Jerusalem
    We approach the formalism of quantum mechanics from the logician point of view and treat the canonical commutation relations and the conventional calculus based on it as an algebraic syntax of quantum mechanics. We then aim to establish a geometric semantics of this syntax. This leads us to a geometric model, the space of states with the action of time evolution operators, which is a limit of finite models. The finitary nature of the space allows us to give a precise meaning and calculate various classical quantum mechanical quantities.
  • 2016 Nov 03

    Monodromy groups & Arithmetics groups

    Lecturer: 

    V.N. Venkataramana
    2:30pm

    Location: 

    Lecture Hall 2
    To a linear differential equation on the projective line with finitely many points of singularities, is associated a monodromy group; when the singularities are "reguar singular", then the monodromy group gives more or less complete information about the (asymptotics of the ) solutions. 

    The cases of interest are the hypergeometric differential equations, and there is much recent work in this area, centred around a question of Peter Sarnak on the arithmeticity/thin-ness of these monodromy groups. I give a survey of these recent results.
  • 2016 Nov 03

    Colloquium: T.N.Venkataramana (Tata Institute) "Monodromy Groups and Arithmetic Groups"

    2:30pm to 3:30pm

    Location: 

    Manchester Building (Hall 2), Hebrew University Jerusalem
    To a linear differential equation on the projective line with finitely many points of singularities, is associated a monodromy group; when the singularities are "reguar singular", then the monodromy group gives more or less complete information about the (asymptotics of the ) solutions.
    The cases of interest are the hypergeometric differential equations, and there is much recent work in this area, centred around a question of Peter Sarnak on the arithmeticity/thin-ness of these monodromy groups. I give a survey of these recent results.
  • 2016 May 26

    Colloquium: John Lott (Berkeley) "3D Ricci flow since Perelman"

    2:30pm to 3:30pm

    Location: 

    Manchester Building (Hall 2), Hebrew University Jerusalem
    I’ll talk about the advances and open questions in three dimensional
    Ricci flow. Topics include the finiteness of the number of surgeries,
    the long-time behavior and flowing through singularities. No prior
    knowledge of Ricci flow will be assumed.
  • 2016 May 19

    Colloquium: Aner Shalev (Hebrew University) "Probability, growth and complexity in groups"

    2:30pm to 3:30pm

    Location: 

    Manchester Building (Hall 2), Hebrew University Jerusalem
    I will describe some recent advances in the study of
    infinite and finite groups, related to probability,
    growth and complexity.
    I will start with the celebrated Tits alternative
    for linear groups, and present extensions and variations,
    including a joint work with Larsen on a probabilistic Tits alternative. This is related to the notion of probabilistic
    identities, and related results and open problems will be
    mentioned.
    I will then discuss approximate subgroups, an important
    result by Breuillard-Green-Tao and Pyber-Szabo, and

Pages