2017
Nov
07

# Eventss

2017
Nov
28

# Dynamics lunch: Benjy Weiss "Rigidity sequences for weakly mixing transformations"

12:00pm to 1:00pm

Here is a title and abstract for the lunch seminar:
Rigidity sequences for weakly mixing transformations
Abstract: I will present a recent result of Bassam Fayad
and Jean-Paul Thouvenot that shows that any rigidty
sequence for an irrational rotation is also a rigidity
sequence for some weakly mixing transformation.

2015
Nov
10

# Dynamics lunch: Lei Yang (HUJI) "Proper affine actions and geodesic flows of hyperbolic surfaces"

12:00pm to 1:00pm

## Location:

Manchester building, Hebrew University of Jerusalem, (Coffee Lounge)

Title: Proper affine actions and geodesic flows of hyperbolic surfaces

2018
Jan
09

# Dynamics Lunch: Raimundo Briceno (TAU) "A Breiman type theorem for Gibbs measures"

12:00pm to 1:00pm

We will review a Breiman type theorem for Gibbs measures due to Gurevich and Tempelman. For a translation invariant Gibbs measure on a suitable translation invariant configuration set X \subset S^G, where G is an amenable group and S is a finite set, we will prove the convergence of the Shannon-McMillan-Breiman ratio on a specific subset of "generic" configurations. Provided that the above Gibbs measure exists, we also prove the convergence in the definition of pressure and the fact that this Gibbs measure is an equilibrium state.

2015
Dec
15

2018
Jan
02

# Dynamics Lunch: Ohad Feldheim (HUJI) "Finitely dependent proper colouring of Z"

12:00pm to 1:00pm

An M-dependent process X(n) on the integers, is a process for which every event concerning with X(-1),X(-2),... is independent from every event concerning with X(M),X(M+1),...
Such processes play an important role both as scaling limits of physical systems and as a tool in approximating other processes.
A question that has risen independently in several contexts is:
"is there an M dependent proper colouring of the integer lattice for some finite M?"

2017
Jun
06

# Dynamics lunch: Tsviqa Lekrec - On Kalikow's T, T^{-1} theorem.

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
Dec
05

# Dynamics Lunch: Jon Aaronson (TA) "Title: "Classical probability theory" for processes generated by expanding C^2 interval maps via quasicompactness."

12:00pm to 1:00pm

Abstract: It was noticed in the 30's by Doeblin & Forte that Markov
operators with "chains with complete connections"
act quasi-compactly on the Lipschitz functions. These are operators
like the transfer operators of certain expanding
C^2 interval maps (e.g. the square of Gauss map).
It is folklore that stochastic processes generated by smooth
observables under these maps satisfy many of the results
of "classical probability theory" (e.g. CLT, Chernoff inequality).
I'll try to explain some of this in a "lunchtime" mode.

2017
Nov
21

2018
Jan
04

# Basic Notions Seminar: Zlil Sela (HUJI) - "Projection complexes, actions on quasi-trees, and applications to mapping class groups of surfaces" (after Bestvina-Bromberg-Fujiwara).

4:00pm to 5:15pm

## Location:

Ross 70

Projection complexes, actions on quasi-trees, and applications to mapping class groups of surfaces (after Bestvina-Bromberg-Fujiwara).

2017
Mar
02

# Basic Notions: Ori Gurel Gurevich (HUJI) - On Smirnov's proof of conformal invariance of critical percolation

4:00pm to 5:00pm

## Location:

Manchester Building, Lecture Hall 2

Abstract:

Let G be an infinite connected graph. For each vertex of G we decide

randomly and independently: with probability p we paint it blue and

with probability 1-p we paint it yellow. Now, consider the subgraph of

blue vertices: does it contain an infinite connected component?

There is a critical probability p_c(G), such that if p>p_c then almost

surely there is a blue infinite connected component and if p

We will focus on planar graphs, specifically on the triangular

Let G be an infinite connected graph. For each vertex of G we decide

randomly and independently: with probability p we paint it blue and

with probability 1-p we paint it yellow. Now, consider the subgraph of

blue vertices: does it contain an infinite connected component?

There is a critical probability p_c(G), such that if p>p_c then almost

surely there is a blue infinite connected component and if p

__p_c or p<p_c.__We will focus on planar graphs, specifically on the triangular

2018
Jan
11

# Basic Notions: Michael Hopkins (Harvard) - Homotopy theory and algebraic vector bundles

4:00pm to 5:15pm

## Location:

Einstein 2

Abstract: This talk will describe joint work with Aravind Asok
and Jean Fasel using the methods of homotopy theory to construct new
examples of
algebraic vector bundles. I will describe a natural conjecture
which, if
true, implies that over the complex numbers the classification
of algebraic
vector bundles over smooth affine varieties admitting an
algebraic cell
decomposition coincides with the classification of topological
complex vector bundles.

2017
Apr
27

# Basic notions: Raz Kupferman

4:00pm to 5:15pm

Abstract:
The “geometrization" of mechanics (whether classical, relativistic or quantum) is almost as old as modern differential geometry, and it nowadays textbook material.
The formulation of a mathematically-sound theory for the mechanics of continuum media is still a subject of ongoing research. In this lecture I will present a geometric formulation of continuum mechanics, starting with the definition of the fundamental physical observables, e.g., force, deformation, stress and traction. The outcome of this formulation is a generalization of Newton’s "F=ma” equation for continuous media.

2018
Jan
14

# Kazhdan Sunday seminars: Tomer Schlank (HUJI) "Topics in algebraic topology".

11:00am to 1:00pm

## Location:

Ross buildings, Room 70A.

10:00-11:00 We will have a special lecture on string diagrams by Shaul Barkan
11:00-13:00 Asaf Horev will continue his talk about ambidexterity and duality

2018
Jan
14

# Kazhdan Sunday seminars: Leonid Polterovich (TAU) "Algebraic methods in symplectic topology"

3:00pm to 5:00pm

## Location:

Ross buildings, Room 70A.

Nick Rozenblyum (Chicago) will talk about Tamarkin's category.