2019 Mar 19

Dynamics lunch: Jing Zhou "“escaping orbit of some piecewise smooth Fermi acceleration model”

12:00pm to 1:00pm

Location:

Manchester faculty club
Following "Dynamics of some piecewise smooth Fermi-Ulam Models” by De Simoi and Dolgopyat.
2019 Mar 12

Dynamics Seminar: Terry Soo (KU) Finitary isomorphism of Bernoulli flows

2:15pm to 3:15pm

Location:

Ross 70
A powerful theory due to Ornstein and his collaborators has been successfully applied to many random systems to show that they are isomorphic to independent and identically distributed systems. The isomorphisms provided by Ornstein's theory may not be finitary, that is, effectively realizable in practice. Despite the large number of systems known to be Bernoulli, there are only a handful of cases where explicit finitary isomorphisms have been constructed. In this talk, we will discuss classical and recent constructions, and some long standing open problems.
2019 Apr 10

Special Analysis Seminar: Dirk Hundertmark (Karlsruhe) "Cwikel's bound reloaded"

2:30pm to 3:30pm

Location:

Sprinzak 24
Abstract: There are a couple of proofs by now for the famous Cwikel--Lieb--Rozenblum (CLR) bound, which is a semiclassical bound on the number of bound states for a Schr\"odinger operator, proven in the 1970s.
2019 Jun 19

Analysis Seminar: Daniel Ofner (HUJI) "Mesoscopic universality for orthogonal polynomial ensembles on the unit circle"

12:00pm to 1:00pm

Location:

Ross 70
Title: Mesoscopic universality for orthogonal polynomial ensembles on the unit circle
2019 May 22

Analysis seminar: Yoel Grinshpon "Fluctuations of linear statistics for Schroedinger operators with a random decaying potential"

12:00pm to 1:00pm

Location:

Ross 70
Title:
Fluctuations of linear statistics for Schroedinger operators with a random
decaying potential
Abstract:
Linear statistics provide a tool for the analysis of fluctuations of random
measures and have been extensively studied for various models in random
matrix theory. In this talk we discuss the application of the same
philosophy to the analysis of the finite volume eigenvalue counting measure
of one dimensional Schroedinger operators and demonstrate it with some
interesting results in the case of a random decaying potential.
2019 Mar 13

Analysis Seminar: Yehuda Pinchover (Technion) "How large can Hardy-weight be?"

12:00pm to 1:00pm

Location:

Ross 70
Title: How large can Hardy-weight be?
Abstract: In the first part of the talk we will discuss the existence of optimal Hardy-type inequalities with 'as large as possible' Hardy-weight for a general second-order elliptic operator defined
on a noncompact Riemannian manifold, while the second part of the talk will be devoted to a sharp answer to the question: "How large can Hardy-weight be?"
2019 Feb 07

Special group actions seminar. On Tame Subgroups of Finitely Presented Groups: Prof. Rita Gitik, University of Michigan, Ann Arbor.

10:00am to 11:00am

Location:

Ross 70
We describe several examples of tame subgroups of finitely
presented groups and prove that the fundamental groups of certain finite
graphs of groups are locally tame.
2019 Jan 23

T&G: Sylvain Cappell (NYU), Atiyah-Bott classes and extending representations of fundamental groups of 3-manifolds from part of the boundary

1:00pm to 2:00pm

Location:

Room 70, Ross Building, Jerusalem, Israel
We consider the problem of extending a representation of the fundamental group of 3-manifolds from part of the boundary surfaces. Applications to links will be discussed. Combining this with some cohomology classes of Atiyah and Bott leads to new multivariable polynomial invariants of 3-manifolds with boundary.
This is joint work with Edward Miller.
No background in 3-dimensional topology will be assumed in this survey and research talk.
2019 Mar 19

Dynamics Seminar: Elon Lindenstrauss (HUJI) - Double variational principle for mean dimension

2:15pm to 3:15pm

Mean dimension is a topological invariant of dynamical systems introduced by Gromov that measures the number of parameters per iteration needed to describe a trajectory in the system. We characterize this invariant (at least for dynamical systems with the marker property, such as infinite minimal systems) using a min-max principle, where choices of both a metric on the topological space and an invariant probability measure on the system are varied.
The work I will report on is joint work with M. Tsukamoto.
2019 Jan 15

T&G: Michael Khanevsky (Technion), Geometry of sets of Hamiltonian isotopic curves in a symplectic surface

2:00pm to 3:30pm

Location:

Room 209, Manchester Building, Jerusalem, Israel

Given two Hamiltonian isotopic curves in a surface, one would like to tell whether they are "close" or "far apart". A natural way to do that is to consider Hofer's metric which computes mechanical energy needed to deform one curve into the other. However due to lack of tools the large-scale Hofer geometry is only partially understood. On some surfaces (e.g. S^2) literally nothing is known.
2019 May 15

Analysis Seminar: Matthias Keller (Potsdam) "Path integral representations for magnetic Schroedinger operators on graphs"

12:00pm to 1:00pm

Location:

Ross 70

Title:
Path integral representations for magnetic Schroedinger operators on graphs
Abstract:
We consider the semigroup and the unitary group of magnetic Schrödinger operators on graphs. Using the ideas of the Feynman Kac formula, we develop a representation of the semigroup and the unitary group in terms of the stochastic process associated with the free Laplacian. As a consequence we derive Kato-Simon estimates for the unitary group. This is joint work with Batu Güneysu (Bonn).
2019 Apr 02

Dynamics Seminar : Yonatan Gutman (IMPAN). On Almost Lossless Compression

2:15pm to 3:15pm

Location:

Ross 70
Abstract: We answer the following questions:
1. Consider a Borel set $X \subset \R^N$ equipped with a probability measure $\mu$. For fixed \$k 2. Can one prove a probabilistic version of Takens delay-embedding theorem with less observations?
3. Is metric mean dimension related to analog compression?
Based on joint works with Krzysztof Barański and Adam Śpiewak.
2019 Jan 09

Set Theory Seminar - Ur Yaar (Set Theory Seminar - Ur Yaar Set Theory Seminar - Ur Yaar Set Theory Seminar - Ur Yaar Set Theory Seminar - Ur Yaar Set Theory Seminar - Ur Yaar )Set Theory Seminar - Ur Yaar Set Theory Seminar - Ur Yaar

2:00pm to 3:30pm

Location:

Ross 73
Title: The Modal Logic of Forcing (Part III)
Abstract: Modal logic is used to study various modalities, i.e. various ways in which statements can be true, the most notable of which are the modalities of necessity and possibility. In set-theory, a natural interpretation is to consider a statement as necessary if it holds in any forcing extension of the world, and possible if it holds in some forcing extension. One can now ask what are the modal principles which captures this interpretation, or in other words - what is the "Modal Logic of Forcing"?
2019 Apr 30

Dynamics Lunch: Nishant Chandgotia "Generic properties of Lebesgue measure preserving transformations of the 2-torus."

12:00pm to 1:00pm

Abstract: In this talk we will discuss some recent work by Guihéneuf and Lefeuvre who prove that shadowing is generic for Lebesgue measure preserving transformations of the 2-torus. We will spend most of our time motivating the problem, discussing the history of such questions- specifically touching upon earlier work of Oxtoby, Ulam, Alpern and Prasad and some general techniques used in the area. Time permitting, we will discuss the recent proof given by Guihéneuf and Lefeuvre.
2019 Mar 27

Eshnav: Prof. Benjamin Weiss : What is a Sofic group?

6:00pm to 7:15pm

Location:

Manchester House, Lecture Hall 2