Events & Seminars

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     Anna Gundert Uli Wagner - Quasirandomness and expansion for graphs

11:30-12:30     Anna Gundert Uli Wagner - Quasirandomness for hypergraphs

13:45- 14:45    Uli Wagner - Szemeredi's regularity lemma for dense graphs

15:00-16:00     Tamar Ziegler - Gowers uniformity norms

16:30-17:30     Anna Gundert Uli Wagner - Hypergraph regularity 
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.
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:
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").
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
2017 May 18

Colloquium: Alex Eskin (Chicago) Dvoretzky Lecure Series, "Polygonal Billiards and Dynamics on Moduli Spaces."

2:30pm to 3:30pm

Location: 

Manchester Building (Hall 2), Hebrew University Jerusalem
Billiards in polygons can exhibit some bizarre behavior, some of which can be explained by deep connections to several seemingly unrelated branches of mathematics. These include algebraic geometry (and in particular Hodge theory), Teichmuller theory and ergodic theory on homogeneous spaces. I will attempt to give a gentle introduction to the subject. A large part of this talk will be accessible to undergraduates.
2017 Apr 27

Colloquium: Gal Binyamini (Weizmann), " Differential equations and algebraic points on transcendental varieties"

2:30pm to 3:30pm

Location: 

Manchester Building (Hall 2), Hebrew University Jerusalem
The problem of bounding the number of rational or algebraic points of a given height in a transcendental set has a long history. In 2006 Pila and Wilkie made fundamental progress in this area by establishing a sub-polynomial asymptotic estimate for a very wide class of transcendental sets. This result plays a key role in Pila-Zannier's proof of the Manin-Mumford conjecture, Pila's proof of the Andre-Oort conjecture for modular curves, Masser-Zannier's work on torsion anomalous points in elliptic families, and many more recent developments.

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