2018
Jan
24

# Events & Seminars

2017
Dec
05

# T&G: Michael Farber (IIAS), Robot motion planning and Bredon equivariant cohomology

12:00pm to 1:30pm

## Location:

Room 70A, Ross Building, Jerusalem, Israel

I will describe a topological approach to the robot motion planning problem focusing mainly on the case of aspherical configuration spaces.

2018
Jan
29

# HD-Combinatorics Special day: Pseudo-randomness (organised by Uli Wagner)

10:00am to 5:00pm

## Location:

IIAS, Feldman Building, Givat Ram

10:00-11:00

11:30-12:30

13:45- 14:45

15:00-16:00

16:30-17:30

**Anna Gundert**/**Uli Wagner**- Quasirandomness and expansion for graphs11:30-12:30

**Anna Gundert**/**Uli Wagner**- Quasirandomness for hypergraphs13:45- 14:45

**Uli Wagner**- Szemeredi's regularity lemma for dense graphs15:00-16:00

**Tamar Ziegler**- Gowers uniformity norms16:30-17:30

**Anna Gundert**/**Uli Wagner**- Hypergraph regularity
2018
Feb
12

2017
Dec
24

# Game Theory & Math Economics: Yonatan Aumann (Bar - Ilan) - "On Time Discounting, Impatience and Risk Aversion"

4:00pm to 4:30pm

## Location:

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

Time discounting is a ubiquitous assumption in economic literature. We (re)explore the foundations of such time preferences. "Impatience" is defined as a preferences for experiencing the better states sooner rather than later, even when there is no uncertainty associated with the future. We show that, assuming consistency and some weak stationarity assumptions, impatience is incompatible with a meaningful notion of a risk-attitude (risk aversion/love/neutrality).On the other hand, if there is uncertainty associated with the future then discounting necessarily emerges.

2017
Dec
10

# Game Theory & Math Economics: Sergiu Hart (HUJI)

4:00pm to 4:30pm

## Location:

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

A unified integral approach to all the calibration results in the literature -- from regular probabilistic calibration to smooth deterministic calibration -- using simple "hairy" fixed point and minimax results.

2018
Jan
14

# Game Theory & Math Economics: Harry Dankowicz (UIUC) "Emergent Task Differentiation on Network Filters"

4:00pm to 4:30pm

## Location:

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

Inspired by empirical observations on honey bee colonies, we analyze the emergence of task differentiation in a model complex system, characterized by an absence of hierarchical control, yet able to exhibit coordinated behavior and collective function. The analysis considers the steady-state response of a mechanical interaction network to exogenous resonant excitation.

2018
Jan
21

2018
Jan
21

2017
May
04

# Colloquium: Jozsef Solymozi (UBC) Erdos Lecture Series, "The sum-product problem"

2:30pm to 3:30pm

## Location:

Manchester Building (Hall 2), Hebrew University Jerusalem

The incompatibility of multiplicative and additive structures in various fields and rings is an important phenomena. In this talk I will talk about a special case of it. Let us consider a finite subset of integers, A. The sum set of A is the set of pairwise sums of elements of A and the product set is the set of pairwise products. Erdős and Szemeredi conjectured that either the sum set or the product set should be large, almost quadratic in size of A. The conjecture is still open. Similar questions can be asked over any ring or field.

2017
Apr
20

# Colloquium - Avraham (Rami) Aizenbud (Weizmann), "Representation count as a Meeting Point for Analysis, Arithmetic, Geometry and Algebra"

2:30pm to 3:30pm

## Location:

Manchester Building (Hall 2), Hebrew University Jerusalem

Consider the following questions:

1. How does the volume of the set f(x_1,...,x_d) < epsilon behaves when epsilon goes to 0?

2. How does the number of solutions of the equation f(x_1,...,x_d) = 0 (mod n) behaves when n goes to infinity.

I will present these and other questions which looks as if they are taken from different areas of mathematics. I'll explain the relation between those questions. Then I'll explain how this relation is used in order to show the following theorem answering a question of Larsen and Lubotzky:

1. How does the volume of the set f(x_1,...,x_d) < epsilon behaves when epsilon goes to 0?

2. How does the number of solutions of the equation f(x_1,...,x_d) = 0 (mod n) behaves when n goes to infinity.

I will present these and other questions which looks as if they are taken from different areas of mathematics. I'll explain the relation between those questions. Then I'll explain how this relation is used in order to show the following theorem answering a question of Larsen and Lubotzky:

2018
May
03

# Colloquium - Dvoretzki lecture 1: Alexei Borodin (MIT) - 'Integrable probability'

2:30pm to 3:30pm

## Location:

Manchester Building (Hall 2), Hebrew University Jerusalem

The goal of the talk is to survey the emerging field of integrable probability, whose goal is to identify and analyze exactly solvable probabilistic models. The models and results are often easy to describe, yet difficult to find, and they carry essential information about broad universality classes of stochastic processes.

2017
Mar
16

# Colloquium: Oren Becker (HUJI) Tzafriri Prize Lecture "Equations in permutations and group theoretic local testability"

2:30pm to 3:30pm

## Location:

Manchester Building (Hall 2), Hebrew University Jerusalem

Abstract: Given two permutations A and B which "almost" commute, are they "close" to permutations A' and B' which really commute? This can be seen as a question about a property the equation XY=YX.

Studying analogous problems for more general equations (or sets of equations) leads to the notion of "locally testable groups" (aka "stable groups").

Studying analogous problems for more general equations (or sets of equations) leads to the notion of "locally testable groups" (aka "stable groups").

2017
Jun
08

# Colloquium: Vadim Kaloshin (Maryland) - "Birkhoff Conjecture for convex planar billiards and deformational spectral rigidity of planar domains"

2:30pm to 3:30pm

## Location:

Manchester Building (Hall 2), Hebrew University Jerusalem

G.D.Birkhoff introduced a mathematical billiard inside of a convex domain as the motion

of a massless particle with elastic reflection at the boundary. A theorem of Poncelet says

that the billiard inside an ellipse is integrable, in the sense that the neighborhood of the

boundary is foliated by smooth closed curves and each billiard orbit near the boundary

is tangent to one and only one such curve (in this particular case, a confocal ellipse).

A famous conjecture by Birkhoff claims that ellipses are the only domains with this

of a massless particle with elastic reflection at the boundary. A theorem of Poncelet says

that the billiard inside an ellipse is integrable, in the sense that the neighborhood of the

boundary is foliated by smooth closed curves and each billiard orbit near the boundary

is tangent to one and only one such curve (in this particular case, a confocal ellipse).

A famous conjecture by Birkhoff claims that ellipses are the only domains with this

2017
Mar
02

# Colloquium - Joram seminar: Hugo Duminil-Copin (Universite de Geneve, IHES), "Proving conformal invariance using discrete holomorphicity"

2:30pm to 3:30pm

## Location:

Manchester Building (Hall 2), Hebrew University Jerusalem

Title: Proving conformal invariance using discrete holomorphicity

Abstract:

Abstract: