2018
Jan
17

# Events & Seminars

2018
Jan
24

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
Feb
12

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
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
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
21

2018
Jan
21

2018
May
17

2017
Mar
23

# Colloquium: Asaf Shapira (Tel Aviv) - "Removal Lemmas with Polynomial Bounds"

2:30pm to 3:30pm

## Location:

Manchester Building (Hall 2), Hebrew University Jerusalem

A common theme in many extremal problems in graph theory is the
relation between local and global properties of graphs. We will
consider the following variant of this theme: suppose a graph G
is far (in some well defined sense) from satisfying property P.
Must G contain a small proof of this fact? We will show that
for many natural graph properties the answer is Yes. In particular,
we will show that the answer is Yes whenever P is a semi-algebraic
graph property, thus conforming a conjecture of Alon.
Joint work with L. Gishboliner

2017
Jun
22

# Colloquium: Zohovitzki prize lecture - Ariel Rapaport, "Self-affine measures with equal Hausdorff and Lyapunov dimensions"

2:30pm to 3:30pm

## Location:

Manchester Building (Hall 2), Hebrew University Jerusalem

A measure on the plane is called self-affine if it is stationary with respect to a finitely supported measure on the affine group of R^2. Under certain randomization, it is known that the Hausdorff dimension of these measures is almost surely equal to the Lyapunov dimension, which is a quantity defined in terms of the linear parts of the affine maps. I will present a result which provides conditions for equality between these two dimensions, and connects the theory of random matrix products with the dimension of self-affine measures.

2017
Mar
09

# Colloquium: Yael Karshon (Toronto) - "Classification results in equivariant symplectic geometry"

2:30pm to 3:30pm

## Location:

Manchester Building (Hall 2), Hebrew University Jerusalem

Abstract: I will report on some old and new classification results
in equivariant symplectic geometry,
expanding on my classification, joint with Sue Tolman,
of Hamiltonian torus actions with two dimensional quotients.

2017
Jun
15

# Colloquium: Alexander Logunov (Tel Aviv), "0,01% Improvement of the Liouville property for discrete harmonic functions on Z^2"

2:30pm to 3:30pm

## Location:

Manchester Building (Hall 2), Hebrew University Jerusalem

Let u be a harmonic function on the plane.
The Liouville theorem claims that if |u| is bounded on the whole plane, then u is identically constant.
It appears that if u is a harmonic function on a lattice Z^2, and |u| < 1 on 99,99% of Z^2,
then u is a constant function.
Based on a joint work(in progress) with L.Buhovsky, Eu.Malinnikova and M.Sodin.