Searching Pareto Optimal Solutions for the Problem of Forming and Restructuring Coalitions in Multi-Agent Systems

Coordination is one of the fundamental research issues in distributed artificial intelligence and multi-agent systems. Current multi-agent coalition formation methods present two limits: First, computation must be completely restarted when a change occurs. Second, utility functions of the agents are either global or aggregated. We present a new algorithm to cope with these limits. The first part of this paper presents a coalition formation method for multi-agent systems which finds a Pareto optimal solution without aggregating the preferences of the agents. This protocol is adapted to problems requiring coordination by coalition formation, where it is undesirable, or not possible, to aggregate the preferences of the agents. The second part of this paper proposes an extension of this method enabling dynamic restructuring of coalitions when changes occur in the system.     

The Core of a Production Economy with Asymmetric Information

The paper analyses the core of a production economy with asymmetric information. Due to the incompleteness of information the transactions an agent can make are restricted. However, if the agent joins a coalition, his information changes according to an exogenously given information rule. The production possibilities of a coalition are described by a technology set and information that the coalition can employ in production. This information depends on the information of the coalition members and is also described by an information rule. Given that the technology sets satisfy some regularity conditions, a production economy with asymmetric information generates a well‐defined cooperative game. It is shown that the core of this game and thus the core of the underlying economy is non‐empty provided that the technology sets satisfy a balancedness condition. This result holds independently of the given information rules.     

Coalition Formation and Stability

This paper aims to develop, for any cooperative game, a solution notion that enjoys stability and consists of a coalition structure and an associated payoff vector derived from the Shapley value. To this end, two concepts are combined: those of strong Nash equilibrium and Aumann–Drèze coalitional value. In particular, we are interested in conditions ensuring that the grand coalition is the best preference for all players. Monotonicity, convexity, cohesiveness and other conditions are used to provide several theoretical results that we apply to numerical examples including real-world economic situations.     

一种贪婪的异构多信道并行合作频谱感知方法

为了同时对多个异构信道进行有效地合作频谱感知,并克服现有方法中只考虑检测准确性而忽略感知开销和系统效益,忽略不同认知用户对不同异构信道感知性能的差异以及参与合作感知的认知用户较多等问题,提出了一种贪婪的异构多信道并行合作频谱感知方法。根据对感知开销和传输收益的定义,充分考虑不同认知用户对不同异构信道感知性能的差异,利用贪婪算法在多个认知用户和多个异构信道间最优地进行感知任务分配,使总系统效益最大。仿真结果表明,所提方法与基于迭代匈牙利的并行合作频谱感知方法、改进的基于迭代匈牙利的并行合作频谱感知方法和随机的合作频谱感知方法相比,能够获得较高的总系统效益,且所需的参加合作感知的认知用户数较少。     

互惠性偏好下的供应链金融委托代理模型比较研究

供应链金融是近年来兴起的用于解决中小企业融资难问题的重要金融创新之一,但目前学术界的研究多以经典的委托代理模型为基准,忽略了供应链金融参与方之间存在着互惠性偏好的倾向。文章简要回顾了委托代理理论的发展脉络,结合行为经济学家Rabin提出的互惠性偏好理论,对委托代理模型进行了行为经济学层面的拓展,以当前流行的供应链金融中核心企业与协作企业委托代理关系为研究对象,比较分析了互惠性偏好引入前后各方的收益情况。文章首先构建了经典的Holmstorm和Milgrom模型,研究了核心企业和协作企业均为理性经济主体情形下的博弈收益情况;其次,通过将互惠性偏好引入到Holmstorm和Milgrom模型中,比较分析了各方收益的变化情况;再次,通过参数校准的方法,进行了具体的数值案例分析;最后对模型未来可能的发展方向进行了展望。研究结果表明：通过引入互惠性偏好,在一定的数学条件下,核心企业和协作企业之间的契约制度设计存在着帕累托改进的空间。     

A Multiagent Approach for Collective Decision Making in Knowledge Management

In this paper we propose an argumentative multiagent model based on a mediator agent in order to automate the resolution of conflicts between decision makers for identifying knowledge that need to be capitalized and that we call “crucial knowledge”. We follow both an argumentative approach and a multi-agent system based on a mediator agent. This new approach allows the mediator agent to elicit preference of decision makers which can be different or even contradictory while exploiting and managing their multiple points of view to identify crucial knowledge. Concrete experiments have been conducted on real data from an automotive company and on randomly generated data. We have observed that a non-argumentative approach is more sensitive to the variation of the number of knowledge than an argumentative one. Indeed, the classification results using the multiagent system are consistent with classifications of human decision makers in nearly 80% of studied cases.     

A Multi-Agent Model for Overlapping Negotiations

In the last few years, research on multi-agent systems has addressed different aspects of intelligent negotiations using methods developed in different domains including game theory, decision theory, and economic models. The research proposed in Andersson and Sandholm (1999), Sandholm (1993), Sandholm and Lesser (1995) and Aknine et?al. (2004), Aknine (2002) are significant examples. However, only some of this work focuses on problems related to complex negotiations, particularly those concerning new generation applications. This new research raises fundamental difficulties we have encountered, especially in overlapping negotiations and combined negotiations. This article is interested essentially in overlapping negotiations, which include several agent roles in a same negotiation. One or more agents may play each of these roles. This work shows that the high-level negotiation models are necessary in order to control the execution of overlapping negotiation processes, since, in these negotiations we are facing both classical problems of multi-agent negotiations based on two agents’ roles and the problems concerned with the interdependence of these negotiations. Synchronization of these different processes is thus necessary because of the multiplicity of the roles. Thus, this paper presents a formalized negotiation model, which deals with this problem. It gives a theoretical analysis of the suggested model and discusses the results of the experimental evaluation. To perform this evaluation, we use the application of intelligent service agencies on the Internet.     

Coalition Formation Procedures: The Impact of Issue Saliences and Consensus Estimation

Coalition formation procedures incorporate two properties that are not often found in other coalition formation models: the choice between different formation paths and constrained consensus positions. However, there are two aspects of coalition formation procedures that are often overlooked: issue saliences and consensus estimation. Issue saliences are a measure of the importance that parties can attribute to issue dimensions. Initially, we employ the classical application to implement issue saliences. The classical application combines the Euclidean distance with the center of gravity as a consensus estimate. Secondly, we introduce a consistent distance application where the coalition consensus position is determined by minimizing the sum of salience-weighted Euclidean distances. The impact of these aspects is examined with the help of both numerical and empirical applications. The results indicate that both the consensus estimation method and the inclusion of issue saliences do not only have an impact on the estimated consensus position. They also determine the individual parties’ preferences towards the potential coalition formation procedures.     

Conflict resolution with robustness in international negotiations: A game theoretic approach

A robust game theoretic approach for constructing effective international concords for conflict solving is discussed. Ann-person cooperative game in characteristic function form is used for international conflict solving via formation of coalitions. The nucleolus and the augmented nucleolus as solution concepts of the game are derived on its alternative forms, and robustness of the solutions when the evaluation of the coalition values is varied is examined. For solving this problem, parametric linear programming is used. This approach provides in a resemblant form an-alternative device to solving the fuzzy linear programming based on interval analysis.     

Allocating Profit Among Rational Players in a Fuzzy Coalition: A Game Theoretic Model

In this paper, the problem of allocation of the profit, obtained from a fuzzy coalition, among its players is considered. It is argued that this allocation is influenced by satisfaction of the players in regards to better performance and success within a cooperative endeavour. Our model is based on the real life situations, where possibly one or more players compromise on their payoffs in order to help forming a coalition. We have developed a dynamic approach to obtain a suitable solution to the corresponding cooperative fuzzy game. Further, the notion of a penalty among the bargaining players is introduced. This would inflict them to reasonable demands only.     

A Hierarchical Clustering Approach Based on Three-Dimensional Gray Relational Analysis for Clustering a Large Group of Decision Makers with Double Information

Two types of information, collectively referred to as double information, are usually required in management decision-making. The first is preference information expressed in a judgment matrix. The second is reference information expressed in a multi-attribute decision matrix. In this paper, we investigate large-scale group clustering problems with double information in group decision-making. We first establish a novel three-dimensional gray correlation degree index, which integrates the alternative decision-making vector, index vector and alternative preference vector, to fully excavate the correlation between decision makers with double information. We then develop a new clustering procedure combining three-dimensional gray relational analysis and the concept of hierarchical clustering. Moreover, a model for determining clustering centers is established on the basis of the maximum gray correlation degree within each cluster and minimum gray correlation degree among clusters. A heuristic algorithm for the model to identify the core decision maker in each cluster is proposed. Finally, we illustrate the applications of the developed procedures with a practical case. The rationality of the proposed method is demonstrated by comparing results with results obtained using other methods, including the traditional gray clustering method and hierarchical clustering method with single information; i.e., preference information or reference information.     

基于合作目标与非合作目标的一体化空间配准新算法

针对移动平台雷达同时探测到合作目标与非合作目标怎样进行空间配准的问题,提出了一种一体化的空间配准算法,将基于合作目标的雷达系统偏差估计结果作为附加条件输入到基于非合作目标建立的线性方程组中,一起采用递推最小二乘法（RLS）重新估计两平台的系统偏差大小。仿真结果表明该新方法切实可行,合理地利用了合作目标信息与共同量测的非合作目标信息,提高了雷达量测系统偏差估计的准确性和最终目标航迹的配准精度,相信在多机协同探测领域具有一定的应用价值。     

Class alliances and conflict: An explanation of political transitions in 19th‐century Europe

I develop a model analyzing common interests and conflict among four classes—capitalists, workers, landlords, and peasants in 19th‐century Europe—and show that strong class position, based on a high degree of organization and solidarity, may actually be detrimental to the economic and political advantage of that class. This occurs when a strong class is excluded from a major class coalition via coalition formation processes. The reason is that the weak class, if they enjoy bargaining power over even weaker classes within a coalition, may not want to form a coalition with the strong class. I apply the main results to coalition formation and political transitions in 19th‐century European society.     

基于网络编码的用户协作分集系统性能分析

针对非协作通信和传统协作通信系统不能达到高天线分集增益的问题,提出基于网络 编码的用户协作系统模型。研究了基于网络编码不同协作用户的天线分集增益,并分析非协 作机制、传统用户协作机制和基于网络编码用户协作机制的中断概率。理论分析和系统仿真 表明,基于网络编码的用户协作系统能显著降低系统中断概率,获得更大的分集增益,且协 作用户数越多,系统分集度越好。     

Logrolling Procedure for Multi-Issue Negotiation

In order to better deal with the complexity in multi-issue negotiation, a quantitative method which produces Pareto optimal solutions through jointly improving exchange of issues is proposed. The trade-off process is modelled using logrolling, in which loss in some issues is traded for gain in others, resulting in overall gain for all parties. This mutual gain approach is designed based on the integrative negotiation strategy. The objective of the logrolling method is in negotiation support by providing a structure and systematic analysis for ill-defined multi-issue negotiation problems. This study presents a formal representation of logrolling, the sequential logrolling procedure that is based on the exchange of two issues, and the general properties of the efficient frontier produced by logrolling under a linear preference assumption. The study also includes some discussion on implementation aspects of the logrolling method.     

网络-信道联合编码的DmF协作通信技术

提出了一种采用网络-信道编码的解调前传(DmF)协作通信方案。与译码前传（DF）相比, DmF协作方式在中继处只对信号进行解调而非译码,因此,大大降低了中继节点的复 杂度。在由两个用户、一个中继节点和一个基站组成的通信模型中,采用LDPC信道编码 与网络编码结合的方式,构造了一种DmF协作传输方式。在基站处,通过构造的〖WTHX〗H〖 WTBZ〗矩阵对 来自两用户及中继的信号进行联合译码。仿真结果表明：所给方案的性能优于非协作方 式及无网络编码的协作通信方式,随着信噪比的增加这种优势会更加明显;另外,DmF的性 能与DF的非常接近,但其设备复杂度却大大降低,因此DmF比DF方式更具实用性。 同时,该方案在降低设备复杂度、减少延迟、有效对抗无线信道慢衰落、提高通信性能及频 谱利用率等方面都是非常有效的。     

混合中继转发机制下的资源分配

在基于放大转发（AF）和译码转发（DF）的混合中继转发机制模型下,为了使系统获得最大和速率,提出了相应的资源分配方案,在子载波对混合中继协议的判断选择和最优功率分配算法的基础上讨论了等效信道增益模型和非等效信道增益模型。在非等效信道增益模型中,为了降低计算复杂度提出了一种次优算法。在该机制模型下,系统自适应地选择AF或者DF转发,既克服了两种单一转发模式存在的弊端,又能获得更大的和速率,从而提高了资源利用率。仿真结果表明,当系统功率等因素变化时,该分配方案下的混合中继转发模型与传统的AF和DF模型相比系统和速率分别提高了60%和8%以上,充分说明了该系统的优越性。     

一种基于混合智能算法的协作中继选择新方法

针对多用户多中继场景下协作通信系统的中继选择问题,提出了一种基于混合智能算法的协作中继选择新方法。不同于现有的为每个源节点分配一个中继节点的中继选择方法,新方法建立了为每个源节点分配一个或多个中继节点的优化模型,以最大化多用户多中继协作系统的最小接收信噪比为优化目标,采用结合了模拟退火与遗传算法的混合智能算法来搜寻中继选择问题的最优解。仿真结果表明,所提方法可显著提高目的端的接收信噪比,且算法具有较强的全局搜索和快速寻优能力。     

Coalition formation in international monetary policy games

This paper analyses coalition formation in monetary policy coordination games between n countries. We show that some but not all countries may join if the decision to be a member of the coalition is incentive-compatible for the individual country. Positive spillovers of the coalition formation process and the resulting free-rider problem limit the stable coalition size: since the coalition members are bound by the union’s discipline, an outsider can successfully export inflation without fearing that the insiders will try to do the same. These ‘gains from staying out’ arise even in the case of symmetric shocks.