不完备偏好下广义强Berge均衡的存在性

本文基于不完备偏好集中元素对应的等价类集是一个偏序集,把不完备偏好问题转化为偏序问题,得到了不完备偏好下的不动点定理,提供一种新的方法证明局中人的决策偏好不满足完备性时,n人非合作博弈中广义强Berge均衡的存在性.     

基于显示、生成偏好的序贯模糊选择函数的研究

本文分别在普通情况以及模糊情况下,对显示偏好、生成偏好合理化的序贯选择函数进行了一定的研究。首先,研究了该序贯合理的选择函数的选择结果与选择顺序无关的条件,其次,研究了选择函数与该序贯合理的选择函数之间的关系。     

医疗服务市场质量竞争博弈模型

以社会福利最大化为目标,建立双寡头垄断下医疗机构质量价格序贯博弈模型,以及在医疗服务价格和财政补偿双重规制下的政府和医疗机构之间的两阶段博弈模型.研究发现:由于医疗服务市场价格竞争削弱了质量竞争效应,序贯博弈的纳什均衡质量低于以社会福利最大化为目标的社会均衡质量.当医疗机构的固定成本控制在某个范围时,政府双重规制下的均衡质量优于医疗机构质量价格序贯博弈下的均衡质量,从而从理论上证明了政府双重规制的有效性.     

多目标决策非凸锥Λ－有效点的存在性与控制性质

本文提出了多目标决策偏好及最优解的一般概念和集诱导偏好的概念．给出了判断ρ－完备集的一系列条件，从而指出了ρ－完备集是十分广泛的集类．得到了集合的Λ－有效点的存在性定理和ρ－下闭集与截面的Λ－有效点的性质．通过引入函数Λ－下半连续的概念，得到了多目标决策一般集诱导偏好最优解的存在性定理．在这些结果的基础上，最后得到了集合Ｙ关于Λ和多目标决策问题的控制性质．     

半连续格的半素极小集与序同态扩张

对完备格引入半素极小集的概念,证明完备格L为半连续格当且仅当L中的每个元在L中存在半素极小集,给出半连续格的两个序同态扩张定理.     

不确定偏好序下的双边匹配博弈

针对带有不确定偏好序的双边匹配问题，现有方法大都仅注重整体收益之和，忽略了参与人的个体收益以及在交互选择中的策略运用.基于最大满意度准则，给出不确定序下的收益（满意度）矩阵的推导过程；然后，从个体理性视角，结合矩阵博弈的思想构建一种兼顾整体和个体收益的博弈匹配优化模型，并证明模型最优解满足纳什均衡.最后，进一步探讨各种策略选择及其优劣分析.     

一种具有不确定偏好序评价信息的群决策方法

针对具有不确定偏好序评价信息的群决策问题,提出了一种决策方法.首先,描述了不确定偏好序的概念,并将它转化为概率向量,同时给出概率向量加权算子;然后,给出了概率向量两两比较的可能度的定义及性质分析;依据概率向量加权算子及可能度,建立了方案两两比较的可能度矩阵;基于可能度矩阵及互补判断矩阵的权重公式,计算方案的优先权重并对方案进行优选;最后,通过一个算例说明了该方法的可行性和有效性.     

不确定偏好序信息下考虑主体心理行为的双边匹配决策方法

针对基于不确定偏好序信息的双边匹配问题,本文提出了一种决策方法。给出了双边匹配和不确定偏好序的相关概念,同时给出了不确定偏好序信息下考虑主体心理行为的双边匹配问题描述;以每个主体给出的临界值作为其参照点,计算了每个主体给出的不确定偏好序相对于参照点的收益或损失;考虑到主体损失规避的心理行为特征,依据TODIM思想计算每个主体对另一方主体的益损值的感知价值;在此基础上,构建了求解该双边匹配问题的双目标优化模型,使用线性加权法将双目标优化模型转化为单目标优化模型,通过求解该单目标优化模型获得匹配结果;最后,通过IT服务外包中的供给方与需求方的双边匹配实例分析说明了所提方法的有效性。     

在消费者偏好不确定下双寡头定位定价博弈

本文通过建立在企业对消费者偏好信息不确定情形下,双寡头企业动态定位、定价博弈模型,研究企业的定位策略、定价策略以及产品差异化问题。证明了该动态博弈存在唯一的子博弈精炼均衡。均衡结果表明,偏好不确定性是一种差异化力量,与消费者偏好信息确定情形相比,企业的不确定性能够提高均衡价格、增加均衡利润。最后,分析了偏好不确定性对社会最优定位和社会最优差异化的影响。     

正则对策的N-M稳定集及其唯一存在定理

研究了有非对称性和负传递性偏好的无限策略对策,提出了N-M稳定集和正则对策的概念,其中N-M稳定集是将合作对策中由Von Neumann 和Morgenstern给出的相应概念引入到策略对策中的.所谓正则对策是指其Nash均衡集中每条链关于一致偏好总有上界的无限策略对策.证明了每个正则对策都有唯一N-M稳定集. 此结果及其应用例子说明正则对策N-M稳定集的概念对于策略对策的纯Nash均衡的精炼起着重要作用.     

Redefinition of Belief Distorted Nash Equilibria for the Environment of Dynamic Games with Probabilistic Beliefs

In this paper, a new concept of equilibrium in dynamic games with incomplete or distorted information is introduced. In the games considered, players have incomplete information about crucial aspects of the game and formulate beliefs about the probabilities of various future scenarios. The concept of belief distorted Nash equilibrium combines optimization based on given beliefs and self-verification of those beliefs. Existence and equivalence theorems are proven, and this concept is compared to existing ones. Theoretical results are illustrated using several examples: extracting a common renewable resource, a large minority game, and a repeated Prisoner’s Dilemma.     

Limit Consistent Solutions in Noncooperative Games

Strong and limit consistency in finite noncooperative games are studied. A solution is called strongly consistent if it is both consistent and conversely consistent (Ref. 1). We provide sufficient conditions on one-person behavior such that a strongly consistent solution is nonempty. We introduce limit consistency for normal form games and extensive form games. Roughly, this means that the solution can be approximated by strongly consistent solutions. We then show that the perfect and proper equilibrium correspondences in normal form games, as well as the weakly perfect and sequential equilibrium correspondences for extensive form games, are limit consistent.     

Sequential Stackelberg equilibria in two-person games

The concept of sequential Stackelberg equilibrium is introduced in the general framework of dynamic, two-person games defined in the Denardo contracting operator formalism. A relationship between this solution concept and the sequential Nash equilibrium for an associated extended game is established. This correspondence result, which can be related to previous results obtained by Baar and Haurie (1984), is then used for studying the existence of such solutions in a class of sequential games. For the zero-sum case, the sequential Stackelberg equilibrium corresponds to a sequential maxmin equilibrium. An algorithm is proposed for the computation of this particular case of equilibrium.This research was supported by SSHRC Grant No. 410-83-1012, NSERC Grant No. A4952, and FCAR Grants Nos. 86-CE-130 and EQ-0428.The authors thank T. R. Bielecki and J. A. Filar, who pointed out some mistakes and helped improving the paper.At the time of this research, this author was with GERMA, Ecole Mohammedia d'Ingénieurs, Rabat, Morocco.     

Cooperative games with imcomplete information

A bargaining solution concept which generalizes the Nash bargaining solution and the Shapley NTU value is defined for cooperative games with incomplete information. These bargaining solutions are efficient and equitable when interpersonal comparisons are made in terms of certainvirtual utility scales. A player's virtual utility differs from his real utility by exaggerating the difference from the preferences of false types that jeopardize his true type. In any incentive-efficient mechanism, the players always maximize their total virtual utility ex post. Conditionally-transferable virtual utility is the strongest possible transferability assumption for games with incomplete information.     

A relation between perfect equilibria in extensive form games and proper equilibria in normal form games

The concept of quasi-perfect equilibria for games in extensive form is introduced. It is shown that a proper equilibrium of a normal form game induces a quasi-perfect equilibrium in every extensive form game having this normal form.     

Nondominated equilibrium solutions of a multiobjective two-person nonzero-sum game in extensive form and corresponding mathematical programming problem

In most of studies on multiobjective noncooperative games, games are represented in normal form and a solution concept of Pareto equilibrium solutions which is an extension of Nash equilibrium solutions has been focused on. However, for analyzing economic situations and modeling real world applications, we often see cases where the extensive form representation of games is more appropriate than the normal form representation. In this paper, in a multiobjective two-person nonzero-sum game in extensive form, we employ the sequence form of strategy representation to define a nondominated equilibrium solution which is an extension of a Pareto equilibrium solution, and provide a necessary and sufficient condition that a pair of realization plans, which are strategies of players in sequence form, is a nondominated equilibrium solution. Using the necessary and sufficient condition, we formulate a mathematical programming problem yielding nondominated equilibrium solutions. Finally, giving a numerical example, we demonstrate that nondominated equilibrium solutions can be obtained by solving the formulated mathematical programming problem.     

Equilibrium selection in multi-leader-follower games with vertical information

We consider two-stage multi-leader-follower games, called multi-leader-follower games with vertical information, where leaders in the first stage and followers in the second stage choose simultaneously an action, but those chosen by any leader are observed by only one “exclusive” follower. This partial unobservability leads to extensive form games that have no proper subgames but may have an infinity of Nash equilibria. So it is not possible to refine using the concept of subgame perfect Nash equilibrium and, moreover, the concept of weak perfect Bayesian equilibrium could be not useful since it does not prescribe limitations on the beliefs out of the equilibrium path. This has motivated the introduction of a selection concept for Nash equilibria based on a specific class of beliefs, called passive beliefs, that each follower has about the actions chosen by the leaders rivals of his own leader. In this paper, we illustrate the effectiveness of this concept and we investigate the existence of such a selection for significant classes of problems satisfying generalized concavity properties and conditions of minimal character on possibly discontinuous data.     

Probabilities of Pure Nash Equilibria in Matrix Games when the Payoff Entries of One Player Are Randomly Selected

The Nash equilibrium in pure strategies represents an important solution concept in nonzero sum matrix games. Existence of Nash equilibria in games with known and with randomly selected payoff entries have been studied extensively. In many real games, however, a player may know his own payoff entries but not the payoff entries of the other player. In this paper, we consider nonzero sum matrix games where the payoff entries of one player are known, but the payoff entries of the other player are assumed to be randomly selected. We are interested in determining the probabilities of existence of pure Nash equilibria in such games. We characterize these probabilities by first determining the finite space of ordinal matrix games that corresponds to the infinite space of matrix games with random entries for only one player. We then partition this space into mutually exclusive spaces that correspond to games with no Nash equilibria and with r Nash equilibria. In order to effectively compute the sizes of these spaces, we introduce the concept of top-rated preferences minimal ordinal games. We then present a theorem which provides a mechanism for computing the number of games in each of these mutually exclusive spaces, which then can be used to determine the probabilities. Finally, we summarize the results by deriving the probabilities of existence of unique, nonunique, and no Nash equilibria, and we present an illustrative example.     

Game theoretic models for climate change negotiations

Negotiations to reduce greenhouse gas accumulation in the atmosphere are modeled as extensive games of perfect information. Various solution concepts, such as Nash equilibrium, reaction function equilibrium, correlated equilibrium and bargaining solutions are applied, analyzed and computed. Special reduction techniques are used when the size of the game tree becomes excessive. A new solution concept, the tree-correlated equilibrium is also introduced. Main features of an Excel add-in designed to compute various solutions are briefly described and a sample policy analysis for a special negotiating scenario is discussed.     

Note Equilibrium payoffs in stochastic games of incomplete information: the general symmetric case

We prove that the existence of equilibrium payoffs for stochastic games of incomplete symmetric information follows from the same result for stochastic games with complete information. Received January 1999/Revised October 2001