2016 Mar 29

Dynamics & probability: Paul Nelson (ETH) - Microlocal lifts and quantum unique ergodicity on GL(2,Q_p)

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

Michael Farber: "Robot motion planning and equivariant Bredon cohomology"

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.

2018 Mar 05

HD-Combinatorics Special Day: Samplers in Computer Science (organized by Amnon Ta-Shma)

(All day)


Room 130, IIAS, Feldman Building, Givat Ram

All talks will be given by Amnon Ta-Shma.
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


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
2017 Nov 21

T&G: Semyon Alesker (Tel Aviv University), Calabi type problem for Monge-Ampere equations on HKT manifolds

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
2015 Nov 22

Game Theory & Math Economics: Sergiu Hart (HUJI) - "Calibrated Forecasts, Leaks, and Game Equilibria" (joint work with Dean P. Foster)

4:00pm to 5:00pm


Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus
How good is a forecaster? Assume for concreteness that every day the forecaster issues a forecast of the type "the chance of rain tomorrow is 30%." A simple test one may conduct is to calculate the proportion of rainy days out of those days that the forecast was 30%, and compare it to 30%; and do the same for all other forecasts. A forecaster is said to be _calibrated_ if, in the long run, the differences between the actual proportions of rainy days and the forecasts are small—no matter what the weather really was.
2016 Jan 10

Game Theory & Math Economics: Francis Bloch (Paris School of Economics) - "Dynamic assignment of objects to queuing agents"

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

Game Theory & Math Economics: Matthew Elliott (Caltech) - "Endogenous Financial Networks: Efficient Modularity and Why Shareholders Prevent It" (joint work with Jonathon Hazell)

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

Game Theory & Math Economics: Liad Blumrosen (HUJI) - "(Almost) Efficient Mechanisms for Bilateral Trading" (joint work with Shahar Dobzinski)

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.
2015 Nov 29

Game Theory & Math Economics: Ran Spiegler (Tel Aviv University and University College London) - "On the "Limited Feedback" Foundation of Boundedly Rational Expectations"

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.