2018 Mar 05

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

(All day)

## Location:

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

Program:

1. 10:00-11:00 - The sampling problem and some equivalent formulations.
Abstract:
We will first define Samplers, and the parameters that
one usually tries to optimize: accuracy, confidence, query complexity
2018 Jan 22

# HD-Combinatorics: Frank Calegari, "Methods for computing homology and cohomology"

9:00am to 11:00am

## Location:

IIAS, Feldman Building, Givat Ram
2018 Mar 22

# Colloquium: Gilles Zemor (Université de Bordeaux) - "Additive Combinatorics in Field Extensions"

3:30pm to 4:30pm

## Location:

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

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

12:00pm to 1:30pm

## Location:

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 01

# Game Theory & Math Economics: Abraham Neyman (HUJI) - "Additive valuations of streams of payoffs that obey the time-value of money principle: Characterization and robust optimization"

4:00pm to 5:00pm

## Location:

Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus
This paper characterizes the ordinal utilities over the bounded infinite streams of payoffs that satisfy the time-value of money principle and an additivity property, and those that in addition are impatient. Building on this characterization, the paper introduces the concept of optimization that is robust to small imprecision in the specification of the preference, and proves that the set of feasible streams of payoffs of a finite Markov Decision Process admits such a robust optimization.
2016 May 15

# Game Theory & Math Economics: Talia Einhorn (Tel Aviv University & Ariel University) - "Israel's Legal Infrastructure – walking on thin ice"

4:00pm to 5:00pm

## Location:

Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus
A sound legal infrastructure is critical to the development of the Israeli economy. In its absence, business people and private persons alike face difficulties in planning their actions. All too often they are obliged to turn to the courts of law. However, in the absence of a proper infrastructure, those do not themselves have the necessary tools to resolve the disputes. The matters at issue are not marginal. They have long-lasting consequences for the economy. The number of publicly-traded companies listed in Tel-Aviv Stock Exchange sank from 657 in 2008 to 461 in March 2016.
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

## Location:

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 Jun 19

# Game Theory & Math Economics: Jacob (Kobi) Glazer (Tel Aviv University) - "Has the National Health Insurance Law Run its Course?"

4:00pm to 5:00pm

## Location:

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

The National Health Insurance Law is operated through several economic mechanisms that are meant to implement its vision. In this lecture we will present the main flaws of some of these mechanisms and propose ways to fix them. The lecture will be in hebrew.

2015 Dec 20

# Game theory & economics: Ariel Porat (Tel-Aviv University) - "Personalizing Negligence Law" (joint work with Omri Ben-Shahar)

4:00pm to 5:00pm

## Location:

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

## Location:

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

## Location:

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

## Location:

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

# Game Theory & Math Economics: Eilon Solan (Tel Aviv University) - "Acceptable Strategy Profiles in Stochastic Games"

4:00pm to 5:00pm

## Location:

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

# 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

## Location:

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

# Game Theory & Math Economics: Eyal Winter (HUJI) - "Rule Rationality" (Joint work with Yuval Heller)

4:00pm to 5:00pm

## Location:

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.