2018 Jun 18

# Combinatorics -- Erdos lecture cancelled; instead (NOTE THE TIME!) :

10:30am to 12:30pm

## Location:

IIAS, Eilat hall, Feldman bldg (top floor), Givat Ram
Speaker: Ilan Newman and Yuri Rabinovich, U.Haifa Title: Sparsifiers - Part I (Part II from 2pm to 4pm, same day and place) Abstract: Time permitting, we plan to discuss the following topics (in this order): 1. * Additive Sparsification and VC dimension * Multiplicative Sparsification * Examples: cut weights, cut-dimension of L_1 metrics, general metrics, and their high-dimensional analogues 2. * Multiplicative Sparsification and Triangular Rank; * Karger-Benczur sparsification of cuts weights 3. * Batson-Spielman-Srivastava sparsification
2018 May 28

# Combinatorics: Daniel Jerison (TAU) "Random walks on sandpile groups"

11:00am to 12:30pm

## Location:

IIAS, Eilat hall, Feldman bldg, Givat Ram
Speaker: Daniel Jarison,  TAU

Title: Random walks on sandpile groups

Abstract:
2018 Jun 25

# Combinatorics: Roman Glebov (HU) "Perfect Matchings in Random Subgraphs of Regular Bipartite Graphs"

11:00am to 12:30pm

## Location:

IIAS, room 130, Feldman bldg, Givat Ram
Speaker: Roman Glebov (HU) Title: Perfect Matchings in Random Subgraphs of Regular Bipartite Graphs Abstract: Consider the random process in which the edges of a graph $G$ are added one by one in a random order. A classical result states that if $G$ is the complete graph $K_{2n}$ or the complete bipartite graph $K_{n,n}$, then typically a perfect matching appears at the moment at which the last isolated vertex disappears. We extend this result to arbitrary $k$-regular bipartite graphs $G$ on $2n$ vertices for all $k=\Omega(n)$.
2018 Jun 12

# Dynamics Lunch: No semimar

12:00pm to 1:00pm

## Location:

Manchester lounge
2018 Apr 30

# High-Dim Combinatorics: Stefan Glock, "Designs via iterative absorption"

9:00am to 10:45am

Speaker: Stefan Glock (U. Birmingham)
Title: Designs via iterative absorption
2018 May 28

# NT&AG: Max Gurevich (University of Singapore), "Branching laws for non-generic representations"

2:00pm to 3:00pm

## Location:

Room 70A, Ross Building, Jerusalem, Israel
The celebrated Gan-Gross-Prasad conjectures aim to describe the branching behavior of representations of classical groups, i.e., the decomposition of irreducible representations when restricted to a lower rank subgroup.
2018 Apr 29

# GAME THEORY AND MATHEMATICAL ECONOMICS RESEARCH SEMINAR:Michal Feldman, Tel Aviv University "Interdependent Values without Single-Crossing (Joint work with Alon Eden, Amos Fiat and Kira Goldner)"

1:30pm to 2:30pm

## Location:

Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus

Abstract:

We consider a setting where an auctioneer sells a single item to n potential agents with {\em interdependent values}. That is, each agent has her own private signal, and the valuation of each agent is a function of all n private signals. This captures settings such as valuations for oil fields, broadcast rights, art, etc.

2018 Apr 25

# Special Talk : Justin Noel (University of Regensburg) - "Blue-shift and thick tensor ideals"

## Lecturer:

Justin Noel (University of Regensburg)
2:30pm to 3:30pm

## Location:

Shprinzak 27

Abstract:

I will discuss a recent generalization of Kuhn's Blue-shift theorem about Tate cohomology. Combining this result with work of Arone, Dwyer, and Lesh we resolve a conjecture of Balmer and Sanders and classify the thick tensor ideals of compact genuine $A$-spectra, where $A$ is a finite abelian group. This is joint work with Tobias Barthel, Markus Hausmann, Niko Naumann, Thomas Nikolaus, and Nathaniel Stapleton.

2018 Jun 05

# Dynamics Lunch: Hagai Lavner (Huji)

12:00pm to 1:00pm

## Location:

Manchester lounge
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.