2018
Jun
05

# Seminars

2018
May
08

# Dynamics Seminar: Tsviqa Lakrec (Huji)

12:00pm to 1:00pm

## Location:

Manchester 209

Consider a simple random walk on $\mathbb{Z}$ with a random coloring of $\mathbb{Z}$.
Look at the sequence of the first $N$ steps taken and colors of the visited locations.
From it, you can deduce the coloring of approximately $\sqrt{N}$ integers.
Suppose an adversary may change $\delta N$ entries in that sequence. What can be deduced now?
We show that for any $\theta<0.5,p>0$, there are $N_{0},\delta_{0}$
such that if $N>N_{0}$ and $\delta<\delta_{0}$ then with probability $>1-p$ we can reconstruct
the coloring of $>N^{\theta}$ integers.

2018
Jun
19

# Tomasz Rzepecki (Uniwersytet Wrocławski): Topological dynamics and Galois groups in model theory

2:15pm to 3:15pm

## Location:

Ross 70

In recent years, topological dynamics have become an important tool in model theory. I will talk about some topological dynamical results from my PhD thesis about the so-called group-like equivalence relations. I plan to give a glimpse of the motivations in model theory (mostly related to the model-theoretic Galois groups and connected components of definable groups) and to show some ideas of the proofs.
I will briefly recall the required notions from topological dynamics. Some knowledge of model theory will help to understand the motivations, but otherwise, it will not be necessary.

2018
Apr
26

# Basic Notions: Alex Lubotzky "From expander graphs to high dimensional expanders: a road map"

4:00pm to 5:30pm

## Location:

Math Hall 2

Expander graphs have been a topic of great interest in the last 50 years for mathematicians and computer scientists. In recent years a high dimensional theory is emerging. We will describe some of its main directions and questions.

2018
May
16

# Analysis Seminar: Nadav Dym (WIS) "Linear algorithms for computing conformal mappings"

12:00pm to 1:00pm

## Location:

Ross Building

Abstract:
(joint with Noam Aigerman, Raz Sluzky and Yaron Lipman)

2018
May
29

# Dynamics Lunch: Matan Seidel (Huji) - "The Mass Transport Principle in Percolation Theory"

12:00pm to 1:00pm

## Location:

Manchester lounge

The Mass Transport Principle is a useful technique that was introduced to the study of automorphism-invariant percolations by Häggström in 1997. The technique is a sort of mass conservation principle, that allows us to relate random properties (such as the random degree of a vertex) to geometric properties of the graph.
I will introduce the principle and the class of unimodular graphs on which it holds, as well as a few of its applications.

2018
May
15

2:15pm to 3:15pm

2018
Jun
27

# Analysis Seminar: Barry Simon (Caltech) "Heinävarra’s Proof of the Dobsch–Donoghue Theorem"

12:00pm to 1:00pm

## Location:

Ross Building, Room 70

Abstract:
In 1934, Loewner proved a remarkable and deep theorem about matrix monotone functions. Recently, the young Finnish mathematician, Otte Heinävarra settled a 10 year old conjecture and found a 2 page proof of a theorem in Loewner theory whose only prior proof was 35 pages. I will describe his proof and use that as an excuse to discuss matrix monotone and matrix convex functions including, if time allows, my own recent proof of Loewner’s original theorem.

2018
May
29

# Yuri Lima (Paris 11): Symbolic dynamics for non-uniformly hyperbolic systems with singularities

2:15pm to 3:15pm

## Location:

Ross 70

Symbolic dynamics is a tool that simplifies the study of dynamical systems in various aspects. It is known for almost fifty years that uniformly hyperbolic systems have ``good'' codings. For non-uniformly hyperbolic systems, Sarig constructed in 2013 ``good'' codings for surface diffeomorphisms. In this talk we will discuss some recent developments on Sarig's theory, when the map has discountinuities and/or critical points, such as multimodal maps of the interval and Bunimovich billiards.

2018
May
08

# Dynamics Seminar: Yinon Spinka (TAU): Finitary codings of Markov random fields

2:15pm to 4:15pm

## Location:

Ross 70

Let X be a stationary Z^d-process. We say that X is a factor of an i.i.d. process if there is a (deterministic and translation-invariant) way to construct a realization of X from i.i.d. variables associated to the sites of Z^d. That is, if there is an i.i.d. process Y and a measurable map F from the underlying space of Y to that of X, which commutes with translations of Z^d and satisfies that F(Y)=X in distribution. Such a factor is called finitary if, in order to determine the value of X at a given site, one only needs to look at a finite (but random) region of Y.

2018
Apr
16

2018
Apr
11

2018
Apr
15

2018
May
22

2018
May
22

# Logic Seminar - Assaf Hasson - "Zilber's trichotomy for strongly minimal groups interpretable in o-minimal structures"

1:30pm to 3:00pm

## Location:

Ross 63

Abstract: We will discuss the main steps in the proof of the theorem stating that if (G,+, ...) is a strongly minimal expansion of a group interpretable in an o-minimal expansion of a field, and \dim(G)=2 then G is a pure algebraic group.
Joint work with P. Eleftheriou and Y. Peterzil.