Seminars

2017 Jun 13

Topology and Geometry Seminar: Alexander Caviedes Castro (Tel-Aviv University), "Symplectic capacities and Cayley graphs"

1:00pm to 1:50pm

Location: 

Ross 70A
Abstract: The Gromov non-squeezing theorem in symplectic geometry states that is not possible to embed symplectically a ball into a cylinder of smaller radius, although this can be done with a volume preserving embedding. Hence, the biggest radius of a ball that can be symplectically embedded into a symplectic manifold can be used as a way to measure the "symplectic size'' of the manifold. We call the square of this radius times the number \pi the Gromov width of the symplectic manifold. The Gromov width as a symplectic invariant is extended through the notion of "Symplectic Capacity".
2016 Feb 28

Game theory & economics: Itzhak Gilboa (Tel Aviv, HEC Paris)

3:30pm to 4:30pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus
Topic: Weighted Utilitarianism, Edgeworth, and the Market (joint work with Rossella Argenziano) Place: Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus Time: Sunday, March 6, 2016 at 4:00 p.m. Refreshments available at 3:30 p.m. YOU ARE CORDIALLY INVITED
2015 Jan 11

Game Theory & Math Economics: Gaëtan FOURNIER (Paris-Sorbonne University) - "Efficiency of Equilibria in Hotelling Games" (joint with Marco Scarsini)

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We consider a Hotelling game where a finite number of retailers choose a location, given that their potential customers are distributed on a network. Retailers do not compete on price but only on location. We show that when the number of retailers is large enough, the game admits a pure Nash equilibrium and we construct it. We then compare the equilibrium cost bore by the consumers with the cost that could be achieved if the retailers followed the dictate of a benevolent planner. We look at this efficiency of equilibrium asymptotically in the number of retailers.
2015 Jan 18

Game Theory & Math Economics: Itai Arieli (Technion) - "Social Learning and the Vanishing Value of Private Information"

4:00pm to 5:00pm

Location: 

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

This paper considers a sequential social learning game with a general utility function, state and action space. We establish that the value of private information converges to zero almost surely in every Perfect Bayesian equilibrium of any sequential social learning game.We use this result to show that totally unbounded signals are necessary and sufficient for asymptotic learning to hold in every sequential social learning game. Finally, we assume that the utility function of each agent is a private random draw and establish robustness of our results. (Joint with M. Mueller-Frank).

2015 Mar 01

Game Theory & Math Economics: Hans Peters (Maastricht University) - "An axiomatic characterization of the Owen-Shapley spatial power index"

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We present an axiomatic characterization of the Owen-Shapley spatial power index for the case where issues are elements of two-dimensional space.This characterization employs a version of the transfer condition, which enables us to unravel a spatial game into spatial games connected to unanimity games. The other axioms are spatial versions of anonymity and dummy, and two conditions concerned particularly with the spatial positions of the players. We show that these axioms are logically independent.
2015 Mar 08

Game Theory & Math Economics: Nabil Al-Najjar (Northwestern University) - "Aggregative Utility in Large Populations" (joint with Luciano Pomatto)

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We Savage's theory to model large populations. Specifically, the notion of aggregative utility capture sensitivity to aggregate uncertainty in a large population. This utility characterizes planners who evaluate lotteries over population profiles according to their expected utility, and whose preferences over deterministic profiles satisfy the Savage postulates. Idiosyncratic risks are ranked separably across the population.
2015 May 03

Game Theory & Math Economics: Philip J. Reny (University of Chicago) - "Sequential Equilibrium in Multi-Stage Games with Infinite Sets of Types and Actions"

4:00pm to 5:00pm

Location: 

Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We consider the question of how to define sequential equilibria for multi-stage games with infinite type sets and infinite action sets. The definition should be a natural extension of Kreps and Wilson's 1982 definition for finite games, should yield intuitively appropriate solutions for various examples, and should exist for a broad class of economically interesting games
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.

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