nep-gth New Economics Papers
on Game Theory
Issue of 2009‒05‒09
ten papers chosen by
Laszlo A. Koczy
Budapest Tech and Maastricht University

  1. Non-cooperative Bargaining and the Incomplete Information Core By Okada, Akira
  2. A Characterization of the Shapley Value for Cooperative Games By Hsiao, Chih-Ru; Chiou, Wen-Lin
  3. Dynamic Unawareness and Rationalizable Behavior By Heifetz, Aviad; Meier, Martin; Schipper, Burkhard C
  4. Stochastically Stable Equilibria in Coordination Games with Multiple Populations By Maruta, Toshimasa; Okada, Akira
  5. The Evolution of Fairness under an Assortative Matching Rule in the Ultimatum Game By Shirata, Yasuhiro
  6. On the Consumer Problem under an Informational Externality By Marc Santugini
  7. Collaborating By Alessandro Bonatti; Johannes Horner
  8. Downsian Model with Asymmetric Information: Possibility of Policy Divergence By Kikuchi, Kazuya
  9. On the Existence of Bayesian Cournot Equilibrium By Einy, Ezra; Haimanko, Ori; Moreno, Diego; Shitovitz, Benyamin
  10. The Role of Social Networks on Regulation in the Telecommunication Industry By Rodrigo Harrison; Gonzalo Hernández; Roberto Muñoz.

  1. By: Okada, Akira
    Abstract: We consider information transmission in the core of an exchange economy with incomplete information by non-cooperative bargaining theory. Reformulating the coalitional voting game by Serrano and Vohra [Information transmission in coalitional voting games, J. of Economic Theory (2007), 117-137] so that an informed agent proposes an allocation, we define a notion of the informational core. A coalition has an informational objection to the status-quo allocation if and only if there exists an equilibrium rejection in the coalitional voting game. We present a non-cooperative sequential bargaining game in which coalitional voting games are repeated, and prove that a refinement of a sequential equilibrium of the bargaining game necessarily yields an allocation in the informational core.
    Keywords: core, exchange economy, incomplete information, information transmission, non-cooperative bargaining
    JEL: C71 C72 D51 D82
    Date: 2009–02
  2. By: Hsiao, Chih-Ru; Chiou, Wen-Lin
    Abstract: Motivated by a case of discrimination against some particular players happened in the real world, we define the partially consistent property of the solutions for cooperative games and use the property to characterize the Shapley value. This is different from the characterization of the Shapley value by applying the consistency property proposed by Hart and Mas-Colell.
    Keywords: Shapley value; Reduced Game; Partialy Consistent
    JEL: C7
    Date: 2009–03–30
  3. By: Heifetz, Aviad; Meier, Martin; Schipper, Burkhard C
    Abstract: We define generalized extensive-form games which allow for mutual unawareness of actions. We extend Pearce's (1984) notion of extensive-form (correlated) rationalizability to this setting, explore its properties and prove existence. We define also a new variant of this solution concept, prudent rationalizability, which refines the set of outcomes induced by extensive-form rationalizable strategies. Finally, we define the normal form of a generalized extensive-form game, and characterize in it extensive-form rationalizability by iterative conditional dominance.
    Keywords: Unawareness; extensive-form games; extensive-form rationalizability; prudent rationalizability; iterative conditional dominance
    JEL: C70 D82 D80 C72
    Date: 2009–05–04
  4. By: Maruta, Toshimasa; Okada, Akira
    Abstract: We investigate the equilibrium selection problem in n-person binary coordination games by means of adaptive play with mistakes (Young 1993). The size and the depth of a particular type of basins of attraction are found to be the main factors in determining the selection outcome. The main result shows that if a strategy has the larger basin of attraction, and if it is deep enough, then the strategy constitutes a stochastically stable equilibrium. The existence of games with multiple stochastically stable equilibria is an immediate consequence of the result. We explicitly address the qualitative difference between selection results in multi-dimensional stochastic evolution models and those in single dimensional models, and shed some light on the source of the difference.
    Keywords: Equilibrium selection, stochastic stability, unanimity game, coordination game
    JEL: C70 C72 D70
    Date: 2009–01
  5. By: Shirata, Yasuhiro
    Abstract: This paper studies how a matching rule affects the evolution of fairness in an ultimatum mini game. Gale et al. [1995] show that only selfish behaviour survives in the deterministic replicator dynamics under the random matching rule. In contrast, this paper shows that, under an assortative matching rule, the fair behaviour may survive at an asymptotically stable state.
    Date: 2008–12
  6. By: Marc Santugini (IEA, HEC Montréal)
    Abstract: We use the Hendricks and Kovenock (1989) framework to study the consumer problem under an informational externality. The informational externality arises when each consumer of a social network is endowed with private information regarding the quality of a good. In such situations, the past purchasing decisions of the consumers are informative and, thus, are used as partially revealing signals of private information. Asymmetric information and the observability of actions render the consumer problem dynamic and strategic because the purchasing decision of a consumer affects the other consumers' future payoffs through the learning process. We show that there exists a unique symmetric Bayesian Nash equilibrium. The informational externality increases the likelihood for a consumer to refrain from purchasing the good immediately in order to make a more informed decision in the future.
    Keywords: consumer problem; dynamic game; informational externality, learning
    JEL: D0 D8
    Date: 2009–04
  7. By: Alessandro Bonatti (Dept. of Economics, Yale University); Johannes Horner (Cowles Foundation, Yale University)
    Abstract: This paper examines moral hazard in teams over time. Agents are collectively engaged in an uncertain project, and their individual efforts are unobserved. Free-riding leads not only to a reduction in effort, but also to procrastination. The collaboration dwindles over time, but never ceases as long as the project has not succeeded. In fact, the delay until the project succeeds, if it ever does, increases with the number of agents. We show why deadlines, but not necessarily better monitoring, help to mitigate moral hazard.
    Keywords: Moral hazard, Teams, Experimentation, Collaboration, Public goods, Learning
    JEL: C72 C73 D83
    Date: 2009–04
  8. By: Kikuchi, Kazuya
    Abstract: This paper presents a model of Downsian political competition in which voters are imperfectly informed about economic fundamentals. In this setting, parties' choices of platforms influence voters' behavior not only through voters' preferences over policies, but also through formation of their expectation on the unknown fundamentals. We show that there exist pure-strategy equilibria in this political game with asymmetric information at which the two parties' policies diverge with positive probability. This result is in contrast with the well-known median voter theorem in the classical model of Downsian competition. We also study refinement of equilibria, and identify the perfect equilibria (Selten, 1975) and the strictly perfect equilibria (Okada, 1981). The Nash equilibria with the strongest asymmetry in the parties' strategies are proved to be strictly perfect.
    Date: 2008–09
  9. By: Einy, Ezra; Haimanko, Ori; Moreno, Diego; Shitovitz, Benyamin
    Abstract: We show that when firms have incomplete information about the market demand and their costs, a (Bayesian) Cournot equilibrium in pure strategies may not exist, or be unique. In fact, we are able to construct surprisingly simple and robust examples of duopolies with these features. However, we also find some sufficient conditions for existence, and for uniqueness, of Cournot equilibrium in a certain class of industries. More general results arise when negative prices are possible.
    Keywords: Oligopoly, Incomplete Information, Bayesian, Cournot, Equilibrium, Existence, Uniqueness
    JEL: C72 D43 L13
    Date: 2008–10
  10. By: Rodrigo Harrison (Instituto de Economía. Pontificia Universidad Católica de Chile.); Gonzalo Hernández; Roberto Muñoz.
    Abstract: This paper studies the welfare implications of equilibrium behavior in a market characterized by competition between two interconnected telecommunication ?rms, subject to constraints: the customers belong to a social network. It also shows that social networks matter because equilibrium prices and welfare critically depend on how people are socially related. Next, the model is used to study e¤ectiveness of alternative regulatory schemes. The standard regulated environement, in which the authority de?nes interconnection ac cess charges as being equal to marginal costs and ?nal prices are left to the market, is considered as a benchmark . Then, we focus on the performance of two di¤erent regulatory interventions. First, access prices are set below marginal costs to foster competition. Second, switching costs are reduced to intensify competition. The results show that the second strategy is more efective to obtain equilibrium prices closer to Ramsey?s level.
    Keywords: Access charges, social networks, random regular graphs.
    JEL: C70 D43 D60
    Date: 2009

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