2016
Mar
08

# Dynamics & probability: Elon Lindenstrauss (Mean dimension and embedding of Z^d actions)

2:00pm to 3:00pm

## Location:

Manchester building, Hebrew University of Jerusalem, (Room 209)

2016
Mar
08

2:00pm to 3:00pm

Manchester building, Hebrew University of Jerusalem, (Room 209)

2016
Mar
29

2:00pm to 3:00pm

Manchester building, Hebrew University of Jerusalem, (Room 209)

Abstract:
There are by now several celebrated measure classification results to the effect that a measure is uniform provided it possesses sufficient "invariance" as quantified by stabilizer, entropy, or recurrence. In some applications, part of the challenge is to identify or construct measures to which these hypotheses apply.

2018
Jan
15

9:00am to 11:00am

IIAS, Feldman Building, Givat Ram

Abstract: The motion planning problem of robotics leads to an interesting invariant of topological spaces, TC(X), depending on the homotopy type of X = the configuration space of the system. TC(X) is an integer reflecting the complexity of motion planning algorithms for all systems (robots) having X as their configuration space. Methods of algebraic topology allow to compute or to estimate TC(X) in many examples of practical interest. In the case when the space X is aspherical the number TC(X) depends only on the fundamental group of X. Read more about Michael Farber: "Robot motion planning and equivariant Bredon cohomology"

2018
Mar
05

(All day)

Room 130, IIAS, Feldman Building, Givat Ram

All talks will be given by

10:00-11:00 - The sampling problem and some equivalent formulations

11:30-12:30 - A basic "combinatorial" construction

14:00-14:45 - Algebraic constructions of randomness condensers

15:15-16:00 - Structured sampling

Program:

1. 10:00-11:00 - The sampling problem and some equivalent formulations.

We will first define Samplers, and the parameters that

one usually tries to optimize: accuracy, confidence, query complexity

2018
Jan
22

2018
Mar
12

2018
Mar
22

3:30pm to 4:30pm

Manchester Building (Hall 2), Hebrew University Jerusalem

Additive combinatorics enable one to characterize subsets S of elements in a group such that S+S has small cardinality. We are interested in linear analogues of these results, namely characterizing subspaces S in some algebras (mostly extension fields) such that the linear span of the set S^2 of products st, for s,t in S, has small dimension. We shall present a linear analogue of a theorem of Vosper which says that under the right conditions, a sufficiently small dimension for S^2 implies that S has a basis of elements in geometric progression.

2017
Nov
21

12:00pm to 1:30pm

Room 70A, Ross Building, Jerusalem, Israel

Real and complex Monge-Ampere equations play a central role in several
branches of geometry and analysis. We introduce a quaternionic version
of a Monge-Ampere equation which is an analogue of the famous Calabi
problem in the complex case. It is a non-linear elliptic equation of second
order on so called HyperKahler with Torsion (HKT) manifolds (the latter
manifolds were introduced by physicists in 1990's). While in full generality
it is still unsolved, we will describe its solution in a special case and some

2016
Jan
10

4:00pm to 5:00pm

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

This paper analyzes the optimal assignment of objects which arrive sequentially to agents organized in a waiting list. Applications include the assignment of social housing and organs for transplants. We analyze the optimal design of probabilistic queuing disciplines, punishment schemes, the optimal timing of applications and information releases. We consider three efficiency criteria: the vector of values of agents in the queue, the probability of misallocation and the expected waste.

2016
May
08

4:00pm to 5:00pm

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

Topic: Endogenous Financial Networks: Efficient Modularity and Why Shareholders Prevent It (joint work with Jonathon Hazell) We consider systemic risk in financial networks, by examining the conflict of interest between debt- and equity-holders. Through trading, banks can diversify their idiosyncratic risks and avoid failures following small shocks. However, the resulting interdependencies can cause multiple failures after large shocks.

2015
Nov
15

3:30pm to 4:30pm

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

We study the simplest form of two-sided markets: one seller, one buyer and a single item for sale. It is well known that there is no fully-efficient mechanism for this problem that maintains a balanced budget. We characterize the quality of the most efficient mechanisms that are budget balanced, and design simple and robust mechanisms with these properties. We also show how minimal use of statistical data can yield good results. Finally, we demonstrate how solutions for this simple bilateral-trade problem can be used as a "black-box" for constructing mechanisms in more general environments.

2016
May
29

4:00pm to 5:00pm

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

I will present a new solution concept for multiplayer stochastic games, namely, acceptable strategy profiles. For each player \(i\) and state \(s\) in a stochastic game, let \(w_i(s)\) be a real number.

2015
Nov
29

4:00pm to 5:00pm

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

A common justification for boundedly rational expectations is that agents receive partial feedback about the equilibrium distribution. I formalize this idea in the context of the "Bayesian network" representation of boundedly rational expectations, presented in Spiegler (2015). According to this representation, the decision maker forms his beliefs as if he Öts a subjective causal model - captured by a directed acyclic graph (DAG) over the set of variables - to the objective distribution.

2015
Dec
27

4:00pm to 5:00pm

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

We study the strategic advantages of following rules of thumb that bundle different games together (called rule rationality) when this may be observed by one’s opponent. We present a model in which the strategic environment determines which kind of rule rationality is adopted by the players. We apply the model to characterize the induced rules and outcomes in various interesting environments. Finally, we show the close relations between act rationality and “Stackelberg stability” (no player can earn from playing first). Refreshments available at 3:30 p.m.

2016
Mar
20

4:00pm to 5:00pm

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

Peretz (2013) showed that, perhaps surprisingly, players whose recall is bounded can correlate in a long repeated game against a player of greater recall capacity. We show that correlation is already impossible against an opponent whose recall capacity is only linearly larger. This result closes a gap in the characterisation of min-max levels, and hence also equilibrium payoffs, of repeated games with bounded recall.