Seminars

2017 Mar 28

Dynamics lunch: Ariel Rapaport

12:00pm to 1:00pm

Location: 

Manchester building, Hebrew University of Jerusalem, (Coffee lounge)
A dimension gap for continued fractions with independent digits (after Kifer, Peres and Weiss)
2017 Mar 07

Dynamics lunch: Eli Glasner (Tel Aviv):Some recent applications of Lovasz's Local Lemma to problems in topological dynamics

12:00pm to 1:00pm

Location: 

Manchester building, Hebrew University of Jerusalem, (Coffee lounge)
I'll report on recent applications of the LLL to two problems in the dynamics of general countable groups. The first concerns the existence of free symbolic minimal actions; the second asks about realizations of URS's (uniformly recurrent subgroups) as stability systems. I'll then concentrate on a solution of Gabor Elek to the second problem in the case of finitely generated groups.
2016 Nov 29

Dynamics lunch: Benjy Weiss (HUJI): On minimally almost periodic amenable groups

12:00pm to 1:00pm

Location: 

Manchester building, Hebrew University of Jerusalem, (Coffee lounge)
I'll report on recent applications of the LLL to two problems in the dynamics of general countable groups. The first concerns the existence of free symbolic minimal actions; the second asks about realizations of URS's (uniformly recurrent subgroups) as stability systems. I'll then concentrate on a solution of Gabor Elek to the second problem in the case of finitely generated groups.
2016 Dec 20

Dynamics lunch: Uri Gabor (HUJI)

12:00pm to 1:00pm

Location: 

Manchester building, Hebrew University of Jerusalem, (Coffee lounge)
I'll report on recent applications of the LLL to two problems in the dynamics of general countable groups. The first concerns the existence of free symbolic minimal actions; the second asks about realizations of URS's (uniformly recurrent subgroups) as stability systems. I'll then concentrate on a solution of Gabor Elek to the second problem in the case of finitely generated groups.
2017 Jan 03

Dynamics & probability: Alon Nishry (U. Michigan): Gaussian complex zeros on the hole event: the emergence of a forbidden region

2:00pm to 3:00pm

Location: 

Manchester building, Hebrew University of Jerusalem, (Room 209)
Consider the Gaussian Entire Function (GEF) whose Taylor coefficients are independent complex-valued Gaussian variables, and the variance of the k-th coefficient is 1/k!. This random Taylor series is distinguished by the invariance of its zero set with respect to the isometries of the complex plane.
2017 Jun 20

Dynamics seminar:Naomi Feldheim (Stanford): Persistence of Gaussian Stationary Processes

2:00pm to 3:00pm

Consider a real Gaussian stationary process, either on Z or on R. That is, a stochastic process, invariant under translations, whose finite marginals are centered multi-variate Gaussians. The persistence of such a process on [0,N] is the probability that it remains positive throughout this interval. The relation between the decay of the persistence as N tends to infinity and the covariance function of the process has been investigated since the 1950s with motivations stemming from probability, engineering and mathematical physics. Nonetheless, until recently, good estimates were
2017 Jan 17

Dynamics & probability: Genadi Levin (HUJI): Monotonicity of entropy for families of interval maps.

2:00pm to 3:00pm

Location: 

Manchester building, Hebrew University of Jerusalem, (Room 209)
I describe a language and set-up for proving monotonicity of entropy for families of interval maps which are defined locally. This can be seen as a local version of Thurston's algorithm. We apply this approach to prove the monotonicity and related results for families that are not covered by other methods (with flat critical point, piecewise linear, Lorenz-type, Arnold family and others) . Joint work with Weixiao Shen and Sebastian van Strien.
2017 Mar 21

Dynamics seminar: Nadav Yesha (Kings College): Pair correlation for quadratic polynomials mod 1

2:00pm to 3:00pm

It is an open question whether the fractional parts of nonlinear polynomials at integers have the same fine-scale statistics as a Poisson point process. We provide explicit Diophantine conditions on the coefficients of degree 2 polynomials under which the limit of an averaged pair correlation density is consistent with the Poisson distribution, using a recent effective Ratner equidistribution result on the space of affine lattices due to Strömbergsson. This is joint work with Jens Marklof.
2016 Nov 29

Dynamics & probability: Ofir David (HUJI), Equidistribution of finite continued fractions.

2:00pm to 3:00pm

Location: 

Manchester building, Hebrew University of Jerusalem, (Room 209)
It is well known that for almost every x in (0,1) its orbit under the Gauss map, namely T(x)=1/x-[1/x], equidistributes with respect to the Gauss-Kuzmin measure. This claim is not true for all x, and in particular it is not true for rational numbers which have finite "orbits" which terminate in 0. In order to still have some equidistribution, we instead group together the orbits corresponding to p/q when q is fixed and (p,q)=1 and ask whether these finite sets equidistribute as q goes to infinity. 
2016 Dec 20

Dynamics & probability: Mike Hochman (HUJI), Dimension of Furstenberg measure of SL_2(R) random matrix products

2:00pm to 3:00pm

Location: 

Manchester building, Hebrew University of Jerusalem, (Room 209)
Given a probability measure mu on the space of 2x2 matrices, there is, under mild conditions, a unique measure nu on the space of lines which is stationary for mu. This measure is called the Furstenberg measure of mu, and is important in many contexts, from the study of random matrix products to recent work on self-affine sets and measures. Of particular importance are the smoothness and dimension of the Furstenberg measure. In this talk I will discuss joint work with Boris Solomyak in which we adapt methods from

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