Events & Seminars

2016 Dec 06

Dynamics & probability: Lucia Simonelli - Absolutely Continuous Spectrum for Parabolic Flows/Maps

2:00pm to 3:00pm

Location: 

Manchester building, Hebrew University of Jerusalem, (Room 209)
This talk will discuss some recent developments in the study of the spectral
properties of parabolic flows and maps. More specifically, it will focus on
the techniques used to determine the spectrum of the time-changes of the
horocycle flow and and the effort to generalize these methods to create conditions
under which a general parabolic flow/map would be expected to have absolutely continuous
spectrum.
2017 May 16

Dynamics seminar: Karoly Simon (Budepest): Singularity of self-similar measures (Joint with Lajos Vago)

2:00pm to 3:00pm

We consider self-similar  Iterated Function System (IFS) on the
line constructed with overlapping cylinders. Recently there have been a
number of outstanding results which have suggested that the overlap has
dramatic change in the most important properties of the IFS only if there is
an exact overlap between some of the cylinders.
In this talk, we point out that this is not always the case, at least as far
as the absolute continuity of self-similar measures is concerned.
Namely, we present some one-parameter families of homogeneous self-
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
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.
2017 Dec 26

Dynamics Seminar: Yuval Peres (Microsoft), "Gravitational allocation to uniform points on the sphere"

2:15pm to 3:15pm

Location: 

Ross 70
Given n uniform points on the surface of a two-dimensional sphere, how can we partition the sphere fairly among them ?    "Fairly" means that each region has the same area.   It turns out that if the given points apply a two-dimensional gravity force to the rest of the sphere, then the basins of attraction for the resulting gradient flow yield such a partition—with exactly equal areas, no matter how the points are distributed. (See the

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