2020 Jan 02

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

12:00pm to 1:00pm


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.
2020 Jan 02

Groups & Dynamics Seminar. Maria Gerasimova (BIU) : “Isoperimetry, Littlewood functions, and unitarisability of group”

10:00am to 11:00am


Ross 70 a
Let Γ be a discrete group. A group Γ is called unitarisable if for any Hilbert space H and
any uniformly bounded representation π : Γ → B(H) of Γ on H there exists a bounded operator
S : H → H such that S^{−1}π(g)S is a unitary representation for any g ∈ Γ. It is well known that
amenable groups are unitarisable. It has been open ever since whether amenability characterises unitarisability of groups.
Dixmier: Are all unitarisable groups amenable?
One of the approaches to study unitarisability is related to the space of the Littlewood functions
2019 Dec 25

Special dynamics seminar: Asaf Katz (Chicago) - Measure rigidity of Anosov flows via the factorization method

1:30pm to 3:30pm


Ross 70
Title - Measure rigidity of Anosov flows via the factorization method.

Abstract: Anosov flows are central objects in dynamics, generalizing the basic example of a geodesic flow over a Riemann surface.

In the talk we will introduce those flows and their dynamical behavior.
Moreover, we show how the factorization method, pioneered by Eskin and Mirzakhani in their groundbreaking work about measure rigidity for the moduli space of translation surfaces, can be adapted to smooth ergodic theory and in particular towards the study of Anosov flows.
2019 Dec 18

Logic Seminar - Jouko Vaananen

11:00am to 1:00pm


Ross building - Room 63

Jouko Vaananen will speak about some new infinitary logics.

On some new infinitary logics

2019 Dec 18

Special Analysis and Mathematical Physics Seminar: Eliran Subag (Courant) "Spherical spin glass models"

2:30pm to 3:30pm



Title: Spherical spin glass models


Abstract: In the 70s, physicists proposed several models fordisordered magnetic alloys called spin glass models. Mathematically, thespherical models are random functions on the sphere in high-dimensions, andmany of the questions physicists are interested in can be phrased aspurely mathematical questions about geometric properties, extreme values,critical points, and Gibbs measures of random functions and the interplaybetween them.


2019 Dec 31

Mike Hochman (HUJI) Equidistribution for toral endomorphisms

2:00pm to 3:00pm


Ross 70

Abstract: Host proved a strengthening of Rudolph and Johnson's measure rigidity theorem: if a probability measure is invariant, ergodic and has positive entropy for the map x2 mod 1, then a.e. point equidisitrbutes under x3 mod 1. Host also proved a version for toral endomorphisms, but its hypotheses are in some ways too strong, e.g. it requires one of the maps to be expanding, so it does not apply to pairs of  automorphisms. In this talk I will present an extension of Host's result (almost) to its natural generality.
2020 Mar 23


Repeats every week every Monday until Mon Jun 29 2020 except Mon Apr 06 2020.
11:00am to 1:00pm


Manchester 110

Speaker: TBA

Title: TBA

Abstract: TBA