nep-gth New Economics Papers
on Game Theory
Issue of 2008‒06‒21
twelve papers chosen by
Laszlo A. Koczy
University of Maastricht

  1. Bayesian games: games of incomplete information By Shmuel Zamir
  2. Cooperative games in Strategic Form By Sergiu Hart; Andreu Mas-Colell
  3. Some Characterizations of Convex Interval Games By Branzei, R.; Tijs, S.H.; Alparslan-Gok, S.Z.
  4. A Value for Directed Communication Situations By Enrique González-Arangüena; Conrado Manuel; Daniel Gomez; René van den Brink
  5. Simultaneous Pooled Auctions with Multiple Bids and Preference Lists By Maarten C.W. Janssen; Vladimir A. Karamychev; Emiel Maasland
  6. An Ascending Multi-Item Auction with Financially Constrained Bidders By Gerard van der Laan; Zaifu Yang
  7. Naked Exclusion: An Experimental Study of Contracts with Externalities By Landeo, Claudia M.; Spier, Kathryn E.
  8. Determinants of In-group Bias: Group Affiliation or Guilt-aversion? By Werner Güth; Matteo Ploner; Tobias Regner
  9. A Model-to-Model Analysis of The Repeated Prisoners' Dilemma: Genetic Algorithms vs. Evolutionary Dynamics By Xavier Vilà
  10. Robust Implementation in General Mechanisms By Dirk Bergemann; Stephen Morris
  11. Social Effects in a Multi-Agent Investment Game. An Experimental Analysis By Luigi Mittone; Matteo Ploner
  12. From Overt to Tacit Collusion By Jeroen Hinloopen; Adriaan Soetevent

  1. By: Shmuel Zamir
    Date: 2008–06–09
  2. By: Sergiu Hart; Andreu Mas-Colell
    Date: 2008–06–09
  3. By: Branzei, R.; Tijs, S.H.; Alparslan-Gok, S.Z. (Tilburg University, Center for Economic Research)
    Abstract: This paper focuses on new characterizations of convex interval games using the notions of exactness and superadditivity. We also relate big boss interval games with concave interval games and obtain characterizations of big boss interval games in terms of exactness and subadditivity.
    Keywords: cooperative interval games;convex games;big boss games;superadditive games;marginal games;exact games
    JEL: C71
    Date: 2008
  4. By: Enrique González-Arangüena (Universidad Complutense de Madrid); Conrado Manuel (Universidad Complutense de Madrid); Daniel Gomez (Universidad Complutense de Madrid); René van den Brink (VU University Rotterdam)
    Abstract: In this paper we introduce an extension of the model of restricted communication in cooperative games as introduced in Myerson (1977) by allowing communication links to be directed and the worth of a coalition to depend on the order in which the players enter the coalition. Therefore, we model the communication network by a directed graph and the cooperative game by a generalized characteristic function as introduced in Nowak and Radzik (1994). We generalize the Myerson value for undirected (or standard) communication situations to the context of directed communication and provide two axiomatizations of this digraph Myerson value using component efficiency and either fairness or the balanced contributions property.
    Keywords: Myerson value; Digraph communication situations
    JEL: C71
    Date: 2008–01–17
  5. By: Maarten C.W. Janssen (Erasmus University Rotterdam); Vladimir A. Karamychev (Erasmus University Rotterdam); Emiel Maasland (Erasmus University Rotterdam)
    Abstract: A simultaneous pooled auction with multiple bids and preference lists is a way to auction multiple objects, in which bidders simultaneously express a bid for each object and a preference ordering over which object they would like to get in case they have the highest bid on more than one object. This type of auction has been used in the Netherlands and in Ireland to auction available spectrum. We show that this type of auction does not satisfy elementary desirable properties such as the existence of an efficient equilibrium.
    Keywords: Simultaneous pooled auctions; Multi-object sealed-bid auctions; Multiple bids; Single-object demand; Preference lists
    JEL: C72 D44
    Date: 2008–03–28
  6. By: Gerard van der Laan (VU University Amsterdam); Zaifu Yang (Yokohama National University)
    Abstract: A number of heterogeneous items are to be sold to a group of potential bidders. Every bidder knows his own values over the items and his own budget privately. Due to budget constraint, bidders may not be able to pay up to their values. In such a market, a Walrasian equilibrium usually fails to exist and also the existing auctions might fail to allocate the items among the bidders. In this paper we first introduce a rationed equilibrium for a market situation with financially constrained bidders. Succeedingly we propose an ascending auction mechanism that always results in an equilibrium allocation and price system. By starting with the reservation price of each item, the auctioneer announces the current prices of the items in each step and the bidders respond with their demand sets at these prices. As long as there is overdemand, the auctioneer adjusts prices upwards for overdemanded items until a price system is reached at which either there is an underdemanded set, or there is neither overdemand nor underdemand anymore. In the latter case the auction stops. In the former case, precisely one item will be sold, the bidder buying the item leaves the auction and the auction continues with the remaining items and the remaining bidders. We prove that the auction finds a rationed equilibrium in a finite number of steps. In addition, we derive various properties of the allocation and price system obtained by the auction.
    Keywords: Ascending auction; multi-item auction; financial constraint
    JEL: D44
    Date: 2008–02–15
  7. By: Landeo, Claudia M.; Spier, Kathryn E.
    Abstract: This paper reports the results of an experiment designed to assess the ability of an incumbent seller to profitably foreclose a market with exclusive contracts. We use the strategic environment described by Rasmusen, Ramseyer, and Wiley (1991) and Segal and Whinston (2000) where entry is unprofitable when sufficiently many downstream buyers sign exclusive contracts with the incumbent. When discrimination is impossible, the game resembles a stag-hunt (coordination) game in which the buyers' payoffs are endogenously chosen by the incumbent seller. Exclusion occurs when the buyers fail to coordinate on their preferred equilibrium. Two-way non-binding pre-play communication among the buyers lowers the power of exclusive contracts and induces more generous contract terms from the seller. When discrimination and communication are possible, the exclusion rate rises. Divide-and-conquer strategies are observed more frequently when buyers can communicate with each other. Exclusion rates are significantly higher when the buyers' payoffs are endogenously chosen rather than exogenously given. Finally, secret offers are shown to decrease the incumbent's power to profitably exclude.
    Keywords: Bargaining with Externalities; Contracting with Externalities; Experiments; Exclusive Dealing; Antitrust; Discrimination; Endogenous Payoffs; Communication; Coordination Games; Equilibrium Selection
    JEL: D86 C9 L0 K0 K21 D4 L1 L4 C72
    Date: 2007–12–11
  8. By: Werner Güth (Max Planck Institute of Economics, Strategic Interaction Group, Jena, Germany); Matteo Ploner (Max Planck Institute of Economics, Strategic Interaction Group, Jena, Germany); Tobias Regner (Friedrich Schiller University, Jena, Germany)
    Abstract: In-group favoritism in social dilemma situations is one of the main findings of studies in Social Identity Theory. We investigate what causes the in-group bias: is it due to mere group affiliation or, alternatively, is guilt-aversion a possible explanation? We induce group membership in a minimal group setting, observe in-/out-group transfers and elicit re- spective beliefs. We ?nd that mere group affiliation affects beliefs and explains a substantial part of the bias, but we also ?nd evidence in favor of guilt-aversion as a source of motivation.
    Keywords: social preferences, experiments, social dilemma, group identity, guilt aversion
    JEL: C72 D01 C91 C92 D84
    Date: 2008–06–10
  9. By: Xavier Vilà
    Abstract: We study the properties of the well known Replicator Dynamics when applied to a finitely repeated version of the Prisoners' Dilemma game. We characterize the behavior of such dynamics under strongly simplifying assumptions (i.e. only 3 strategies are available) and show that the basin of attraction of defection shrinks as the number of repetitions increases. After discussing the difficulties involved in trying to relax the 'strongly simplifying assumptions' above, we approach the same model by means of simulations based on genetic algorithms. The resulting simulations describe a behavior of the system very close to the one predicted by the replicator dynamics without imposing any of the assumptions of the analytical model. Our main conclusion is that analytical and computational models are good complements for research in social sciences. Indeed, while on the one hand computational models are extremely useful to extend the scope of the analysis to complex scenar
    Keywords: Agent-Based Computational Economics, Evolutionary Game Theory, Replicator Dynamics, Model-to-Model Analysis, Repeated Prisoners' Dilemma
    JEL: C63 C72 D82
    Date: 2008–06–11
  10. By: Dirk Bergemann (Cowles Foundation, Yale University); Stephen Morris (Dept. of Economics, Princeton University)
    Abstract: A social choice function is robustly implemented if every equilibrium on every type space achieves outcomes consistent with it. We identify a robust monotonicity condition that is necessary and (with mild extra assumptions) sufficient for robust implementation. Robust monotonicity is strictly stronger than both Maskin monotonicity (necessary and almost sufficient for complete information implementation) and ex post monotonicity (necessary and almost sufficient for ex post implementation). It is equivalent to Bayesian monotonicity on all type spaces.
    Keywords: Mechanism design, Implementation, Robustness, Common knowledge, Interim equilibrium, Dominant strategies
    JEL: C79 D82
    Date: 2008–06
  11. By: Luigi Mittone; Matteo Ploner
    Abstract: We experimentally investigate social effects in a principal-agent setting with incomplete contracts. The strategic interaction scheme is based on the Investment Game (Berg et al., 1995). In our setting four trustees and one trustor are interacting and the access to choices of peers in the group of trustees is experimentally manipulated. We find that when the trust- worthiness of some participants is made available to peers, the high levels of trustworthiness displayed by those being observed tend to negatively impact on the trustworthiness of those observing them.
    Date: 2008
  12. By: Jeroen Hinloopen (University of Amsterdam); Adriaan Soetevent (University of Amsterdam)
    Abstract: Recent laboratory experiments support the popular view that the introduction of corporate leniency programs has significantly decreased cartel activity. The design of these repeated game experiments however is such that engaging in illegal price discussions is the only way for subjects to avoid the one-shot competitive equilibrium. Subjects in the experiment of this paper have multiple feasible Nash equilibrium strategies to avoid the competitive equilibrium. These strategies differ in the difficulty of the coordination problem they have to solve. The experimental results show that if the efforts of the antitrust authority and the leniency program are directed exclusively to the most straightforward collusive scheme, subjects manage to switch to a more intricate form of coordination. This shift from overt collusion to tacit collusion questions the acclaimed success of corporate leniency programs.
    Keywords: overt collusion; tacit collusion; corporate leniency program; antitrust policy
    JEL: C72 C92 L41
    Date: 2008–06–09

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