D Monderer - Academia.edu (original) (raw)

Papers by D Monderer

Every game in strategic form can be extended by adding a correlation device. Any Equilibrium in s... more Every game in strategic form can be extended by adding a correlation device. Any Equilibrium in such an extended game is called a correlated equilibrium (Aumann 1974). Aumann showed that there exist games, where the agents surplus in a correlated equilibrium is greater than their surplus in every equilibrium. This suggests the study of two major measures for the value of correlation: 1. The ratio between the maximal surplus obtained in an correlated equilibrium to the maximal surplus obtained in equilibrium. We refer to this ratio as the mediation value. 2. The ratio between the optimal surplus to the maximal surplus obtained in correlated equilibrium. We refer to this ratio as the enforcement value. In this work we initiate the study of the mediation value and of the enforcement value, providing several general results on the value of correlation as captured by these concepts. We also present a set of results for the more specialized case of congestion games, a class of games that ...

We consider a resource selection game with incomplete in- formation about the resource-cost funct... more We consider a resource selection game with incomplete in- formation about the resource-cost functions. All the players know is the set of players, an upper bound on the possible costs, and that the cost functions are positive and nondecreas- ing. The game is played repeatedly and after every stage each player observes her cost, and the actions of all play- ers. For every > 0 we prove the existence of a learning -equilibrium, which is a profile of algorithms, one for each player such that a unilateral deviation of a player is, up to not beneficial for her regardless of the actual cost functions. Furthermore, the learning equilibrium yields an optimal so- cial cost.

We investigate the paths of pure strategy profiles induced by the fictitious play process. We pre... more We investigate the paths of pure strategy profiles induced by the fictitious play process. We present rules that such paths must follow. Using these rules we prove that every non-degenerate 2*3 game has the continuous fictitious play property, that is, every continuous fictitious play process, independent of initial actions and beliefs, approaches equilibrium in such games.

The model of a non-Bayesian agent who faces a repeated game with incomplete information against N... more The model of a non-Bayesian agent who faces a repeated game with incomplete information against Nature is an appropriate tool for modeling general agent-environment interactions. In such a model the environment state (controlled by Nature) may change arbitrarily, and the feedback/reward function is initially unknown. The agent is not Bayesian, that is he does not form a prior probability neither on the state selection strategy of Nature, nor on his reward function. A policy for the agent is a function which assigns an action to every history of observations and actions. Two basic feedback structures are considered. In one of them -- the perfect monitoring case -- the agent is able to observe the previous environment state as part of his feedback, while in the other -- the imperfect monitoring case -- all that is available to the agent is the reward obtained. Both of these settings refer to partially observable processes, where the current environment state is unknown. Our main resul...

Journal of Artificial Intelligence Research

Correlated equilibrium generalizes Nash equilibrium to allow correlation devices. Correlated equi... more Correlated equilibrium generalizes Nash equilibrium to allow correlation devices. Correlated equilibrium captures the idea that in many systems there exists a trusted administrator who can recommend behavior to a set of agents, but can not enforce such behavior. This makes this solution concept most appropriate to the study of multi-agent systems in AI. Aumann showed an example of a game, and of a correlated equilibrium in this game in which the agents' welfare (expected sum of players' utilities) is greater than their welfare in all mixed-strategy equilibria. Following the idea initiated by the price of anarchy literature this suggests the study of two major measures for the value of correlation in a game with nonnegative payoffs: 1. The ratio between the maximal welfare obtained in a correlated equilibrium to the maximal welfare obtained in a mixed-strategy equilibrium. We refer to this ratio as the mediation value. 2. The ratio between the maximal welfare to the maximal w...

Proceedings Fourth International Conference on MultiAgent Systems, 2000

Proceedings of the 4th ACM conference on Electronic commerce - EC '03, 2003

This paper discusses an interested party who wishes to influence the behavior of agents in a game... more This paper discusses an interested party who wishes to influence the behavior of agents in a game (multi-agent interaction), which is not under his control. The interested party cannot design a new game, cannot enforce agents' behavior, cannot enforce payments by the agents, and cannot prohibit strategies available to the agents. However, he can influence the outcome of the game by committing to non-negative monetary transfers for the different strategy profiles that may be selected by the agents. The interested party assumes that agents are rational in the commonly agreed sense that they do not use dominated strategies. Hence, a certain subset of outcomes is implemented in a given game if by adding nonnegative payments, rational players will necessarily produce an outcome in this subset. Obviously, by making sufficiently big payments one can implement any desirable outcome. The question is what is the cost of implementation? In this paper we introduce the notion of k-implementation of a desired set of strategy profiles, where k stands for the amount of payment that need to be actually made in order to implement desirable outcomes. A major point in k-implementation is that monetary offers need not necessarily materialize when following desired behaviors. We define and study k-implementation in the contexts of games with complete and incomplete information. In the latter case we mainly focus on the VCG games. Our setting is later extended to deal with mixed strategies using correlation devices. Together, the paper introduces and studies the implementation of desirable outcomes by a reliable party who cannot modify game rules (i.e. provide protocols), complementing previous work in mechanism design, while making it more applicable to many realistic CS settings.

Algorithmic Game Theory, 2009

Consider a model with a finite number of alternatives, and buyers with private values and quasi-l... more Consider a model with a finite number of alternatives, and buyers with private values and quasi-linear utility functions. A domain of valuations for a buyer is a monotonicity domain if every finite-valued monotone randomized allocation rule defined on it is implementable, in the sense that there exists a randomized truth-telling direct mechanism, which implements this allocation rule. The domain is a weak monotonicity domain if every deterministic monotone allocation rule defined on it is implementable. I discuss the literature on (weak) monotonicity domain, which includes the early mathematical literature as well as the recent CS/Economics literature.

Proceedings of the 6th international joint conference on Autonomous agents and multiagent systems - AAMAS '07, 2007