Repeated proximity games

We consider repeated games with complete information and imperfect monitoring, where each player is assigned a fixed subset of players and only observes the moves chosen by the players in this subset. This structure is naturally represented by a directed graph. We prove that a generalized folk theorem holds for any payoff function if and only if the graph is 2-connected, and then extend this result to the context of finitely repeated games. Received June 1997/Revised version March 1998     

A model of far-sighted electoral competition

A model is described in which candidates adopt positions in sequences of election contests against opponents randomly drawn from a large population. Symmetric steady-state equilibria of the model require rational selection of positions by all candidates against the aggregated behavior of the population, taking into account constraints which an individual's current selections impose on his future selections.     

A two-population game in observable double-ended queuing systems

In this study, the existing game theoretical framework is extended to strategic queuing in search of solutions for a two-population game in observable double-ended queuing systems with zero matching times. We show that multiple Nash equilibria and one unique subgame perfect Nash equilibrium exist in this game.     

On Exiting After Voting

We consider the problem of a society whose members must choose from a finite set of alternatives. After knowing the chosen alternative, members may reconsider their membership by either staying or exiting. In turn, and as a consequence of the exit of some of its members, other members might now find undesirable to belong to the society as well. For general exit procedures we analyze the exit behavior of members after knowing the chosen alternative. For the case of monotonic preferences we propose, for each chosen alternative, an unambiguous and meaningful prediction of the subset of members that will exitWe thank Salvador Barberà, Carmen Beviá, David Cantala, Howard Petith, William Thomson, Marc Vorsatz, and Associate Editor, and two anonymous referees for their helpful comments and suggestions. The work of D. Berga is partially supported by Research Grants 9101100 from the Universitat de Girona, and also by AGL2001-2333-C02-01 and SEJ2004-03276 from the Spanish Ministry of Science and Technology and from the Spanish Ministry of Education and Science, respectively. The work of G. Bergantiñ os is partially supported by Research Grants BEC2002-04102-C02-01 from the Spanish Ministry of Science and Technology and PGIDIT03PXIC30002PN from the Xunta de Galicia. The work of J. Massó is partially supported by Research Grants BEC2002-02130 from the Spanish Ministry of Science and Technology and 2001SGR-00162 from the Generalitat de Catalunya. The work of D. Berga and J. Massó is also partially supported by the Barcelona Economics Program (CREA). The work of A. Neme is partially supported by Research Grant 319502 from the Universidad Nacional de San Luis     

Partnership formation based on multiple traits

A model of partnership formation based on two traits, called beauty and character, is presented. There are two classes of individual and partners must be of different classes. Individuals prefer prospective partners with a high beauty measure and of a similar character. This problem may be interpreted as e.g. a job search problem in which the classes are employer and employee, or a mate choice problem in which the classes are male and female. Beauty can be observed instantly. However, a costly date (or interview) is required to observe the character of a prospective partner. On observing the beauty of a prospective partner, an individual decides whether he/she wishes to date. During a date, the participants observe each other’s character and then decide whether to form a pair. Mutual acceptance is required both for a date to occur and pair formation. On finding a partner, an individual stops searching. Beauty has a continuous distribution on a finite interval, while character ‘forms a circle’ and has a uniform distribution. Criteria based on the concept of a subgame perfect Nash equilibrium are used to define a symmetric equilibrium of this game. It is argued that this equilibrium is unique. When dating costs are high, this equilibrium is a block separating equilibrium as in more classical formulations of two-sided job search problems. However, for sufficiently small dating costs the form of this equilibrium is essentially different.     

Forming coalitions and the Shapley NTU value

A simple protocol for coalition formation is presented. First, an order of the players is randomly chosen. Then, a coalition grows by sequentially incorporating new members in this order. The protocol is studied in the context of non-transferable utility (NTU) games in characteristic function form. If (weighted) utility transfers are feasible when everybody cooperates, then the expected subgame perfect equilibrium payoff allocation anticipated before any implemented game is the Shapley NTU value.     

Social norms and choice: a weak folk theorem for repeated matching games

A folk theorem which holds for all repeated matching games is established. The folk theorem holds any time the stage game payoffs of any two players are not affinely equivalent. The result is independent of population size and matching rule—including rules that depend on players choices or the history of play.      

Cournot–Walras equilibrium as a subgame perfect equilibrium

In this paper, we investigate the problem of the strategic foundation of the Cournot–Walras equilibrium approach. To this end, we respecify à la Cournot–Walras the mixed version of a model of simultaneous, noncooperative exchange, originally proposed by Lloyd S. Shapley. We show, through an example, that the set of the Cournot–Walras equilibrium allocations of this respecification does not coincide with the set of the Cournot–Nash equilibrium allocations of the mixed version of the original Shapley’s model. As the nonequivalence, in a one-stage setting, can be explained by the intrinsic two-stage nature of the Cournot–Walras equilibrium concept, we are led to consider a further reformulation of the Shapley’s model as a two-stage game, where the atoms move in the first stage and the atomless sector moves in the second stage. Our main result shows that the set of the Cournot–Walras equilibrium allocations coincides with a specific set of subgame perfect equilibrium allocations of this two-stage game, which we call the set of the Pseudo–Markov perfect equilibrium allocations. We would like to thank Pierpaolo Battigalli, Marcellino Gaudenzi, and an anonymous referee for their comments and suggestions.     

Repeated newsvendor game with transshipments under dual allocations

We study a repeated newsvendor game with transshipments. In every period n retailers face a stochastic demand for an identical product and independently place their inventory orders before demand realization. After observing the actual demand, each retailer decides how much of her leftover inventory or unsatisfied demand she wants to share with the other retailers. Residual inventories are then transshipped in order to meet residual demands, and dual allocations are used to distribute residual profit. Unsold inventories are salvaged at the end of the period. While in a single-shot game retailers in an equilibrium withhold their residuals, we show that it is a subgame-perfect Nash equilibrium for the retailers to share all of the residuals when the discount factor is large enough and the game is repeated infinitely many times. We also study asymptotic behavior of the retailers’ order quantities and discount factors when n is large. Finally, we provide conditions under which a system-optimal solution can be achieved in a game with n retailers, and develop a contract for achieving a system-optimal outcome when these conditions are not satisfied.     

A regular equilibrium solves the extended HJB system

Control problems not admitting the dynamic programming principle are known as time-inconsistent. The game-theoretic approach is to interpret such problems as intrapersonal dynamic games and look for subgame perfect Nash equilibria. A fundamental result of time-inconsistent stochastic control is a verification theorem saying that solving the extended HJB system is a sufficient condition for equilibrium. We show that solving the extended HJB system is a necessary condition for equilibrium, under regularity assumptions. The controlled process is a general Itô diffusion.     

不完备偏好扩展式博弈的序贯均衡

将Kreps和Wilson提出的序贯均衡解概念推广到了存在不完备偏好的情形.首先给出了一个修正的颤抖手完美均衡的概念,然后应用它去证明不完备偏好扩展式博弈序贯均衡的存在性.     

Two-party competition with many constituences

The paper considers a single member district, simple plurality political system with n districts. There are two political parties, each consisting of n candidates. Individual candidates seek to win their district per se, but voters appreciate that final policy outcomes will depend upon: (1) which party wins control of the legislature, and (2) how party policy is derived from the party members' policies. Candidates take account of such voter deliberations in choosing their election strategies. A set of minimal sufficient conditions for an equilibrium to exist in this game is provided and the equilibrium characterized. While party policies are shown to converge in equilibrium, candidate policies in general do not - either across or within parties.     

防范道德风险的博弈分析和契约设计

运用不完全信息动态博弈的理论，建立了一个防范道德风险的博弈模型．给出了该博弈的精炼贝叶斯纳什均衡．在此基础上给出了基于最优博弈策略的契约的具体形式。而这种基于博弈论的契约可以克服有成本的状态验证模型(CSV)及经典激励理论中承诺的可信性问题。     

On time-inconsistent stopping problems and mixed strategy stopping times

A game-theoretic framework for time-inconsistent stopping problems where the time-inconsistency is due to the consideration of a non-linear function of an expected reward is developed. A class of mixed strategy stopping times that allows the agents in the game to jointly choose the intensity function of a Cox process is introduced and motivated. A subgame perfect Nash equilibrium is defined. The equilibrium is characterized and other necessary and sufficient equilibrium conditions including a smooth fit result are proved. Existence and uniqueness are investigated. A mean–variance and a variance problem are studied. The state process is a general one-dimensional Itô diffusion.     

寡头市场的一类动态博弈模型

首先讨论了寡头垄断市场中n批厂商分批(每批至少有两个以上的厂商)先后进入某行业各批厂商依次且每批同时选择其产量的动态博弈模型的子博弈精练解及其相关结论,探讨了此结论与有关问题的比较分析,并给出此问题的几种特殊情况,说明了此模型的广泛性和实用性.     

重复博弈下借款人违约风险研究

通过建立投资人和平台多方均面临借款人违约风险的不完全信息博弈模型,寻找单次博弈的均衡点,再将博弈重复无限次得出了新的均衡.     

含成本因素的出口退税的博弈模型研究

利用博弈论的分析方法进一步考虑成本因素 ,在更为一般的条件下分别建立了税务机关与外贸企业之间的完全信息静态博弈模型和无限阶段重复博弈模型 .得到国家税务机关最优混合策略及其骗税罚款系数公式 ,并且讨论了多种因素对局中人的影响 ,提出了降低企业骗税概率的建议 .     

Flexibility in a Stackelberg leadership with differentiated goods

We study the effects of product differentiation in a Stackelberg model with demand uncertainty for the first mover. We do an ex-ante and ex-post analysis of the profits of the leader and of the follower firms in terms of product differentiation and of the demand uncertainty. We show that even with small uncertainty about the demand, the follower firm can achieve greater profits than the leader, if their products are sufficiently differentiated. We also compute the probability of the second firm having higher profit than the leading firm, subsequently showing the advantages and disadvantages of being either the leader or the follower firm.