
on Game Theory 
By:  Flesch János; Schoenmakers Gijs; Vrieze Koos (METEOR) 
Abstract:  We examine productgames, which are nplayer stochastic games satisfying: (1) the state space is a product S(1)×…×S(n); (2) the action space of any player i only depends of the ith coordinate of the state; (3) the transition probability of moving from s(i) ∈ S(i) to t(i) ∈S(i), on the ith coordinate S(i) of the state space, only depends on the action chosen by player i. So, as far as the actions and the transitions are concerned, every player i can play on the ith coordinate of the productgame without interference of the other players. No condition is imposed on the payoff structure of the game. We focus on productgames with an aperiodic transition structure, for which we present an approach based on socalled communicating states. For the general nplayer case, we establish the existence of 0equilibria, which makes productgames one of the first classes within nplayer stochastic games with such a result. In addition, for the special case of twoplayer zerosum games of this type, we show that both players have stationary 0optimal strategies. Both proofs are constructive by nature. 
Keywords:  Economics (Jel: A) 
Date:  2007 
URL:  http://d.repec.org/n?u=RePEc:dgr:umamet:2007010&r=gth 
By:  Predtetchinski Arkadi (METEOR) 
Abstract:  The paper examines bargaining over a onedimensional set of social states, with a unanimity acceptance rule. We consider a class of deltaequilibria, i.e. subgame perfect equilibria in stationary strategies that are free of coordination failures in the response stage.We show that along any sequence of deltaequilibria, as delta converges to one, the proposal of each player converges to the same limit. The limit, called the bargaining outcome, is uniquely determined by the set of players, the recognition probabilities, and the utility functions, and it is independent of the choice of the sequence. We characterize the bargaining outcome as a unique solution of a characteristic equation. 
Keywords:  mathematical economics; 
Date:  2007 
URL:  http://d.repec.org/n?u=RePEc:dgr:umamet:2007011&r=gth 
By:  Agnieszka Rusinowska (GATE  Groupe d'analyse et de théorie économique  [CNRS : UMR5824]  [Université Lumière  Lyon II]  [Ecole Normale Supérieure Lettres et Sciences Humaines]) 
Abstract:  The paper concerns a certain modification of the generalized HoedeBakker index  a notion defined for a social network of players. In the original HoedeBakker set up, preferences of players are involved. It is assumed that a player has an inclination either to accept or to reject a proposal, but due to the influence of others, his final decision may be different from his original inclination. In this paper, we propose the notpreferencebased (NPB) generalized HoedeBakker index, where feasible strategies instead of players' inclinations are considered. We show that if all feasible strategy profiles are equally probable, then the NPB generalized HoedeBakker index is a ‘net' Success, i.e., ‘Success  Failure', where Success and Failure of a player is defined as the probability that the player is successful and fails, respectively. Moreover, under the assumption of equal probabilities of all feasible strategy profiles, we show that the probability that a player is lucky (Luck) equals the probability that he fails (Failure). Since Success  Luck = Decisiveness, it follows that, under the same assumption, the NPB generalized HoedeBakker index is equal to the probability that a player is decisive. 
Keywords:  decisiveness ; failure ; feasible strategy ; HoedeBakker index ; success 
Date:  2007–04–19 
URL:  http://d.repec.org/n?u=RePEc:hal:papers:halshs00142482_v1&r=gth 
By:  Agnieszka Rusinowska (GATE  Groupe d'analyse et de théorie économique  [CNRS : UMR5824]  [Université Lumière  Lyon II]  [Ecole Normale Supérieure Lettres et Sciences Humaines]); Michel Grabisch (CRMSEM  Centre de recherches de mathématiques, statistiques et économie mathématique  [CNRS : UMR8095]  [Université PanthéonSorbonne  Paris I]) 
Abstract:  In the paper, we investigate the HoedeBakker index  the notion which computes the overall decisional ‘power' of a player in a social network. It is assumed that each player has an inclination (original decision) to say ‘yes' or ‘no' which, due to influence of other players, may be different from the final decision of the player. The main drawback of the HoedeBakker index is that it hides the actual role of the influence function, analyzing only the final decision in terms of success and failure. In this paper, we further investigate the HoedeBakker index, proposing an improvement which fully takes into account the mutual influence among players. A global index which distinguishes an influence degree from a ‘power' index is analyzed. We define weighted influence indices, in particular, a possibility influence index which takes into account any possibility of influence, and a certainty influence index which expresses certainty of influence. We consider different influence functions and study their properties. 
Keywords:  HoedeBakker index ; influence function ; influence indices 
Date:  2007–04–19 
URL:  http://d.repec.org/n?u=RePEc:hal:papers:halshs00142479_v1&r=gth 
By:  Klaus Bettina; Klijn Flip; Walzl Markus (METEOR) 
Abstract:  In this note we extend Jackson and WattsJET2002''s result on the coincidence of Sstochastically stable and core stable networks from the marriage problem to the solvable roommate problem. In particular, we show that the polarization structure of the marriage problem on which the proof of Jackson and WattsJET2002 hinges, is not crucial for their result. 
Keywords:  microeconomics ; 
Date:  2007 
URL:  http://d.repec.org/n?u=RePEc:dgr:umamet:2007012&r=gth 
By:  AlcaldeUnzu Jorge; Vorsatz Marc (METEOR) 
Abstract:  We propose a new class of voting rules, called Size Approval Voting. According to this rule, the effective weight of a vote from a given individual depends on how many other alternatives the very same individual votes for. In particular, weights are assumed to be nonnegative and weakly decreasing in the number of approved alternatives. Then, for a given profile of individual votes, all those alternatives with the maximal sum of weighted votes are elected. We show in our axiomatic analysis that the family of all Size Approval Voting is characterized by a set of natural properties. 
Keywords:  Economics (Jel: A) 
Date:  2007 
URL:  http://d.repec.org/n?u=RePEc:dgr:umamet:2007008&r=gth 
By:  Fernando Aguiar; Pablo BranasGarza; Maria Paz Espinosa; Luis M. Miller (Max Planck Institute of Economics Jena, Strategic Interaction Group) 
Abstract:  This paper aims to analize the role of personal identity in decision making. To this end, it starts by reviewing critically the growing literature on economics and identity. Considering the ambiguities that the concept of social identity poses, our proposal focuses on the concept of personal identity. A formal model to study how personal identity enters in individualsâ€™ utility function when facing a Dictator Game decision is then presented. Finally, this "identitybased" utility function is studied experimentally. The experiment allows us to study the main parameters of the model, suggesting that we should move with caution when attributing identities to individuals. 
Keywords:  personal identity, dictator game, game theory, experiments 
JEL:  A13 C72 C91 
Date:  2007–04–20 
URL:  http://d.repec.org/n?u=RePEc:jrp:jrpwrp:2007007&r=gth 
By:  Antoine Terracol (GREMARS et Centre d'Economie de la Sorbonne); Jonathan Vaksmann (Centre d'Economie de la Sorbonne) 
Abstract:  This paper uses experimental data to examine the existence of a teaching strategy among bounded rational players. If players realize that their own actions modify their opponent's beliefs and actions, they might play certain actions to this specific end ; and forego immediate payoffs if the expected payoffs if the expected payoff gain from a teaching strategy is high enough. Our results support the existence of a teaching strategy in several ways : First they show that players update their beliefs in order to take account of the reaction of their opponents to their own action. Second, we examine if players actually use a teaching strategy by playing an action that induces a poor immediate payoff but is likely to modify the opponent's behavior so that a preferable outcome might emerge in the future. We find strong evidence of such a strategy in the data and confirm this finding within a logistic model which suggests that the future expected payoff that could arise from a teaching strategy has indeed a significant impact on choice probabilities. Finally, we investigate the effective impact of a teaching strategy on achieved outcomes and find that efficient teachers can successfully use teaching in order to reach their favorite outcome at the expense of their opponents. 
Keywords:  Game theory, teaching, beliefs, experiment. 
JEL:  C72 C91 D83 
Date:  2007–03 
URL:  http://d.repec.org/n?u=RePEc:mse:cesdoc:bla07017&r=gth 
By:  Jordi Brandts; Christiane Schwieren 
Abstract:  Decisionmakers are sometimes influenced by the way in which choice situations are presented to them or "framed" This can be seen as an important challenge to the social sciences, since strong and pervasive framing effects would make it difficult to study human behavior in a synthetic or theoretic manner. We present results from experiments with dilemma games designed to shed light on the effects of several frame variations. We study, among others, the particular public bad frame used by Andreoni (1995) and two more naturalistic frames involving stories. Our results show that none of the frame manipulations have a significant effect on average behavior, but we do find some effects on extreme behavior. We also find that incentives do matter where frames do not matter. 
Keywords:  Framing, Experiments, Public Goods 
JEL:  C92 H41 
Date:  2007–03–15 
URL:  http://d.repec.org/n?u=RePEc:aub:autbar:695.07&r=gth 
By:  Shingo Ishiguro (Graduate School of Economics, Osaka University) 
Abstract:  This paper investigates the holdup problem in the dynamic search market where buyers and sellers search for their trading partners and specific investments are made after match but before trade. We show that frictionless (competitive) market imposes severe limitations on attainable efficiencies: Markets with small friction make the holdup problem more serious than those with large friction because in any equilibrium, whether stationary or nonstationary, investment must be dropped down to the minimum level and trade must be delayed with positive probability. 
Keywords:  Delay of Trade, Holdup Problem, Search 
JEL:  C72 C78 
Date:  2007–05 
URL:  http://d.repec.org/n?u=RePEc:osk:wpaper:0713&r=gth 