Seminars

2015 May 17

Game Theory & Math Economics: Yonatan Aumann (Bar-Ilan University) - "A Conceptual Foundation for the Theory of Risk Aversion"

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
Classically, risk aversion is equated with concavity of the utility function.  In this work we explore the conceptual foundations of this  definition.  In accordance with neo-classical economics, we seek a  definition that is based solely on the decisions maker's preference  order, independent of numerical values. We present two such definitions, based on simple, conceptually appealing interpretations  of the notion of risk-aversion.
2015 May 31

Game Theory & Math Economics: Ben Brooks (University of Chicago) - "An algorithm for two-player stochastic games with perfect monitoring"

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We study the subgame perfect equilibria of two-player stochastic  games with perfect monitoring for a fixed discount factor. We develop a novel algorithm that, starting from larger  correspondences, spirals inwards towards the state-dependent equilibrium payoff correspondence. At each iteration, starting from  a vector of pivot points that are on the boundaries of each state's candidate equilibrium payoff set, we shave off part of each state's  set of payoffs in a carefully chosen direction. The pivots are then advanced in this direction.
2015 Jun 07

Game Theory & Math Economics: Yuval Peres (Microsoft Research) - "Towards Optimal Algorithms for Prediction with Expert Advice"

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We study the classical problem of prediction with expert advice in the adversarial setting with a geometric stopping time. Cover (1965) gave the optimal algorithm that minimizes worst-case regret for the case of 2 experts. In this talk, I will describe the optimal algorithm, adversary and regret for the case of 3 experts. We will see that optimal algorithm for 2 and 3 experts is a probability matching algorithm (analogous to Thompson sampling) against a particular randomized adversary.
2015 Oct 25

Game Theory & Math Economics: Sergiu Hart (HUJI) - "Evidence Games: Truth and Commitment" (joint work with Ilan Kremer, and Motty Perry)

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
An evidence game is a strategic disclosure game in which an agent who has different pieces of verifiable evidence decides which ones to disclose and which ones to conceal, and a principal chooses an action (a "reward"). The agent's preference is the same regardless of his information (his "type")—he always prefers the reward to be as high as possible—whereas the principal prefers the reward to fit the agent's type.
2016 Jan 03

Game Theory & Math Economics: Ilan Kremer (HUJI) - "Voluntary Tests and Disclosure: Benefits of Minimum Standards"

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We analyze a model of voluntary information disclosure and acquisition. An agent chooses among different certification options, may privately obtain verifiable results, and decides whether to disclose them before selling an asset. We show that equilibria are informationally inefficient and that agents choose certifications that are too easy to pass. Self-regulation or a monopolist certifier do not help resolve the inefficiency.
2016 Mar 13

Game Theory & Math Economics: Amir Ban (Tel-Aviv University) - "When should an expert make a prediction?" (joint work with Yossi Azar, Yishay Mansour)

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We consider a setting where in a future known time, a certain continuous variable will be realized.There is a public prediction that converges to its value, and an expert has access to a more accurate prediction.Our goal is to study when should the expert reveal his information, assuming that his reward is based on a logarithmic market scoring rule (i.e., his reward is proportional to the gain in log likelihood of the realized value).Our contributions are: (1) we show that the optimal expert policy is threshold based.
2018 Feb 07

Game Theory & Math Economics: Noam Nisan (HUJI) - "Pricing Complexity"

6:45pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
As economic systems "move" to the Internet, they can become much more complex and this new complexity often becomes their defining characteristic.  We will consider a very simple scenario of this form: a single seller that is selling multiple items to a single buyer.  We will discuss the question of how  *complex* must the pricing scheme be in order for the seller to maximize (approximately, at least) his revenue.Based on joint works with Sergiu Hart, with Shaddin Duhgmi and Li Han and with Moshe Babioff and Yannai Gonczarowski. 
2016 May 22

Game Theory & Math Economics: Christian C. Opp (University of Pennsylvania) - "Can Decentralized Markets be More Efficient?" (joint work with Vincent Glode)

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
Decentralized markets are often characterized as opaque and prone to trade delays, leading to the perception that they are less efficient  than standard centralized limit order markets. We show that in the presence of information  asymmetries decentralized markets can promote higher trade efficiency  than centralized limit order markets through at least two channels.
2016 Nov 13

Game Theory & Math Economics: Rasmus Ibsen-Jensen (IST Austria) - "Complexity of Good Strategies in Stochastic Games"

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
he talk will attempt to characterize good strategies for some special cases of stochastic games. For instance, the talk will argue that there might always be a good strategy with a certain property for all games in a special case of stochastic games or that no good strategy exists that have some property for some game.
2016 Nov 27

Game Theory & Math Economics: Alex Gershkov - "The Dimensions of Consensus" (joint with B. Moldovanu and X. Shi)

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We study a multi-dimensional collective decision under incomplete information. With votes taken by simple majority in each dimension, the outcome is the coordinate-wise median. But, judicious rotations of the orthogonal axes - the dimensions, or issues that are voted upon - lead to welfare improvements. Such rotations cover the entire set of anonymous, Pareto efficient and dominant strategy incentive compatible mechanisms in our environment (Kim and Rousch (1984) and Peters et. al (1992)).
2016 Dec 04

Game Theory & Math Economics: Phil Reny (University of Chicago) - "Broad Sequential Equilibria of Multi-Stage Games with Infinite Sets of Signals and Actions"

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We extend Kreps and Wilson's 1982 definition of sequential equilibrium to multi-stage games with infinite sets of signals and actions. We define “broad sequential epsilon-equilibria” by properties of “sequential epsilon-rationality” and “broad consistency.” Given beliefs, a player's strategy is sequentially epsilon-rational if, at every date t, at every possible signal outside a uniformly unlikely set, the player cannot expect to gain more than epsilon by any feasible deviation.
2016 Dec 18

Game Theory & Math Economics: Eran Shmaya (Northwestern University) - "Recursive Utility and Structural Uncertainty" (joint with Nabil Al-Najjar)

4:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We consider a decision maker with recursive utility, as formalized by Epstein and Zin (1989). We show that, as this decision maker  becomes more patient, his ranking of conditionally i.i.d. processes is approximately that of an expected utility decision maker.
2017 Jan 01

Game Theory & Math Economics: Galit Ashkenazi-Golan (HUJI) - "What You Get is What You See: Cooperation in Repeated Games with Observable Payoffs" (joint with Ehud Lehrer)

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We consider two-player repeated games, where the players observe their own payoffs with a positive probability. Typically, a player observes neither the other's actions nor her payoff.  We show that knowing her own payoff is sufficient to obtain any strictly efficient payoff  by sequential equilibrium, when costly communication is available and the players are  sufficiently patient.

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