Effects of strategy switching and network topology on decision-making in multi-agent systems

To study why the altruistic cooperation can emerge and maintain among self-interested individuals, researchers across several disciplines have made contributions for the solutions of this fascinating problem. Among this, a most-often used framework to describe cooperative dilemma is the evolutionary game theory. In traditional settings, an ideal hypothesis that individuals can feasibly obtain related partners' pay-offs for strategy updating is often adopted. However, considering the impracticality in acquiring accurate pay-offs of referential objects at each round of interaction, we propose switching probability which is independent of pay-offs and denotes the willingness of any individual shifts to another strategy. Here we provide results for the evolutionary dynamics driven by the switching probability in a three-strategy game model, played by the fully connected populations. The findings inform the befitting design of switching probabilities which maximally promote cooperation. We also derive general results that characterise the interaction of the three strategies: coexistence of multiple strategies or domination by some strategy.     

Automated contracting in distributed manufacturing among independent companies

So far, most distributed scheduling systems have been designed for cooperative agents, and are inappropriate for self-interested agents, as for example in inter-firm interactions such as virtual enterprises. This paper discusses issues that arise in extending automated contracting to operate among such self-interested agents. We construct a leveled commitment contracting protocol that allows self-interested agents to efficiently accommodate future events by having the possibility of unilaterally decommitting from a contract based on local reasoning. A decommitment penalty is assigned to both agents in a contract to be freed from the contract, an agent only pays this penalty to the other party. It is formally shown that this leveled commitment feature in a contracting protocol increases Pareto efficiency of deals and can enable contracts by making them individually rational when no full commitment contract can. The analysis is nontrivial because self-interested agents decommit manipulatively a Nash equilibrium analysis of the decommitting game is necessary.     

基于演化博弈的P2P网络资源共享机制的研究

根据P2P网络的自组织、动态性、可扩展性等特点,针对当前P2P网络资源共享的微观、静态等研究方法的局限性,运用演化博弈理论方法,建立了一个P2P网络节点资源共享机制的演化博弈模型,分析了网络节点资源共享的动态演变过程。研究结果表明,该系统的演化方向与双方博弈的支付矩阵相关,同时与系统初始状态相关。并得出,共享产生的超额利润、共享的初始成本、节点服务能力的差异及其贴现因子是影响网络资源共享演变的关键因素。     

系统直和博弈模型下的合作演化

演化博弈论是生物进化论与博弈论结合产生的理论,已成为研究合作演化行为的有力工具.本文研究了基于系统直和博弈模型下的合作演化行为.首先,利用复制者方程分析了双人双策略及三策略对称博弈的演化动力学过程.然后,以石头剪刀布模型和雪堆模型为基础,采用矩阵直和构建系统直和博弈模型,并将所构造的直和矩阵转化为含参数的系统总支付矩阵.随后,说明了这种方法可推广到n个博弈的情形.最后,利用MATLAB对系统直和博弈模型进行仿真模拟,从系统整体的角度分析合作演化.仿真结果表明,混合之后的系统直和博弈较单一博弈而言,合作策略的占比明显增加,且整个系统稳定性更好.这种合作演化机制呈现了全局互惠.     

时间尺度与选择倾向性协同作用下的演化博弈模型

针对合作行为的涌现与维持问题，基于演化博弈理论和网络理论，提出了一种促进合作的演化博弈模型。该模型同时将时间尺度、选择倾向性引入到演化博弈中。在初始化阶段，根据持有策略的时间尺度将个体分为两种类型：一种个体在每个时间步都进行策略更新；另一种个体在每一轮博弈后，以某种概率来决定是否进行策略更新。在策略更新阶段，模型用个体对周围邻居的贡献来表征他的声誉，并假设参与博弈的个体倾向于学习具有较好声誉邻居的策略。仿真实验结果表明，所提出的时间尺度与选择倾向性协同作用下的演化博弈模型中，合作行为能够在群体中维持；惰性个体的存在不利于合作的涌现，但是个体的非理性行为反而能够促进合作。     

基于演化博弈的供应网络企业收益与合作行为的关系仿真

利用演化博弈的理论, 探讨了供应网络中处于不同位置的核心企业和非核心企业两个群体间的成员其投入合作的策略根据收益变化而改变的演化过程; 建立了复制动态方程并求得平衡点解, 据此通过复制动态的相位图直观反映了博弈的演化稳定策略; 并通过Netlogo软件对企业行为选择与收益的关系进行了仿真, 其行为选择的演化结果与相位图展示结果具有一致性。研究结论表明, 收益获得及变化是企业合作行为改变以及合作策略选择的重要依据, 企业间演化稳定策略不仅仅局限于参与合作与放弃合作, 长时间观望也是企业可能的策略选择; 最后针对如何提高供应网络企业间合作的稳定性提出了对策建议。     

Promoting cooperation by setting a ceiling payoff for defectors under three-strategy public good games

The puzzle of altruistic behaviours among multi-agent systems poses a dilemma, which has been an overlapping topic that covers many subjects. The public goods game can be regarded as a paradigm for modelling and exploring it. In the traditional definition of public goods game, the equally divided benefit among all participants leads to the dominance of defection. Much effort has been made to explain the evolution of cooperation, including the model in which the payoff ceilings for defectors are introduced. Further, we study a three-strategy evolutionary public goods game by providing the role of being loners. The payoff ceilings will take effect when the number of cooperators exceeds some threshold. Analysis results by following the replicator dynamics indicate that lower values of the payoff ceilings can better promote levels of public cooperation. Importantly, a remarkable cyclic route has been found: when receiving relative lower benefits, loners act as catalysts, helping the population to escape from mutual defection to cooperation. And, the stable equilibrium points from cooperation to isolation can be realised by improving the fixed payoffs of loners. Finally, broader ceilings also for cooperators provide us more hints about how to suppress the spreading of defectors under certain conditions.     

一种改进的企业竞争合作进化博弈模型

结合企业决策风格,提出一种引入企业声誉的竞争合作进化博弈模型。该模型以企业声誉传播半径为基础定义邻居企业,从邻居企业中选择博弈对象企业,根据其决策风格产生连续博弈序列,得到博弈收益和企业声誉,并通过计算企业吸引值选择学习对象企业。实验结果表明,该模型可有效区分不同声誉的企业,并使具有良好声誉的企业表现出较强的生存优势以及较高的存活率。     

考虑市场因素的电力系统供需互动混合博弈强化学习算法

为对电力市场环境下电力系统供需互动问题更精确地建模,使其更好地与未来电力市场环境下需求侧负荷聚合商之间多变的关系和复杂的通信拓扑结构相匹配,本文将电力系统供需互动的Stackelberg博弈与复杂网络上反映需求侧负荷聚合商互动的演化博弈相结合,搭建考虑市场因素的电力系统供需互动混合博弈模型.并提出混合博弈强化学习算法求解相应的非凸非连续优化问题,该算法以Q学习为载体,通过引入博弈论和图论的思想,把分块协同和演化博弈的方法相结合,充分地利用博弈者之间互动博弈关系所形成的知识矩阵信息,高质量地求解考虑复杂网络上多智能体系统的非凸优化问题.基于复杂网络理论搭建的四类3机-6负荷系统和南方某一线城市电网的仿真结果表明:混合博弈强化学习算法的寻优性能比大多数集中式的智能算法好,且在不同网络下均可以保证较好的寻优结果,具有很强的适应性和稳定性.     

EquiCast: Scalable multicast with selfish users

Peer-to-peer (P2P) networks suffer from the problem of “freeloaders”, i.e., users who consume resources without contributing anything in return. In this paper, we tackle this problem taking a game theoretic perspective by modeling the system as a non-cooperative game. We introduce EquiCast, a wide-area P2P multicast protocol for large groups of selfish nodes. EquiCast is the first P2P multicast protocol that is formally proven to enforce cooperation in selfish environments. Additionally, we prove that EquiCast incurs a low constant load on each user.     

The Dynamics of the Electronic Market: An Evolutionary Game Approach

The capabilities afforded by network technologies have facilitated the growth of electronic commerce. However, online frauds pose serious challenges to the further adoption of the electronic market. In order to promote trust and reduce transaction risks, various trusted third parties have emerged and new models have been proposed. Will people use the trusted third parties while conducting online transactions? How will the electronic market evolve? This research attempts to identify the different equilibria of the electronic market using an evolutionary game theoretic approach and to explore the best strategy to do transactions in the electronic market. Also, the work provides a theoretical justification to the emergence and necessity of trusted third parties for electronic transactions.     

(A)Social reputation: Exploring the relationship between online video game involvement and social competence

Affordable and accessible Internet has changed the way video games are played, allowing individuals to connect worldwide in shared gaming spaces. On the surface participation within these environments may seem socially beneficial, as these highly social, playful spaces allow players to connect, interact with, and learn from others. However, there is a growing concern that increased participation within online gaming environments comes with a wide variety of social consequences, contributing to numerous losses in ‘offline’ sociability. While considerable research has examined these claims, consistent relationships between social competence and online video game involvement have yet to be established. The current work (N = 515) aimed to examine the extent to which online video game involvement may support, or undermine, the development and maintenance of traditional social skills. The results indicate that there are unique relationships between social skills and video game involvement within online gaming populations. However, among online video game players, these links were not as negative or broad as hypothesized. The results of this assessment dispute the anecdotal attribution of a global level of social ineptitude amongst online video game players and provide insight into the potential effects of online video game play on skill development and maintenance.     

Best neighbor strategy to enforce cooperation among selfish nodes in wireless ad hoc network

Trust among nodes in a self-organizing network such as a mobile ad hoc network presents a number of problems and paradoxes. One of the challenging characteristics of wireless and mobile ad hoc networks consists in exploring ways to cope up with selfish behavior of neighbors towards network functions such as routing and forwarding. This paper attempts to deal with such mechanisms and as a result it introduces a distinct model to study the behavior of selfish neighbors using strategic, non-cooperative game theory. Many research works have used Tit-For-Tat strategy for analysis when they deploy game theory to stimulate cooperation. A compliant and an adaptable strategy called Best Neighbor Strategy [BNS] is proposed in this paper for the packet forwarding game in a wireless ad hoc environment. The behavior of nodes is probed varying the proportion of selfishness and also the size of the population while forwarding the packets. The investigations have brought out that the proposed cooperation enforcement policy is scalable, is able to converge faster and is robust against selfishness. BNS achieves evolutionary stability even under the invasion of selfish strategy at different proportions. Further, BNS proves to be a pure evolutionary stable strategy as it evolves to dominate the population from whatever the initial frequency it starts with and it totally out-competes the malign behavior shown by selfish strategy, which means that BNS is immune to invaders. The observations and analysis have shown that the ad hoc paradigm can be modeled significantly using an approach, which has been developed for game theory.     

市场竞争下平台与零售商的物流服务决策研究

近年来电商平台自营商品和零售商开辟线上销售渠道已非常普遍。拥有自建物流体系的电商平台不仅为电子零售商提供线上市场和物流服务,同时还建立线上自营店与电子零售商竞争市场,这种处于相互合作竞争关系下双方的物流服务决策行为值得研究。因此,运用委托代理理论,建立电商平台与电子零售商的两阶段动态博弈模型,分析不同情况下双方的最优物流服务决策。研究发现：存在一个市场需求和佣金率阈值,对于市场需求小于此阈值,电商平台收取佣金率高于此阈值的商品,电商平台能为电子零售商提供更高水平的物流服务和收取更低的物流费用,此时电子零售商会使用电商平台提供的物流服务,双方能实现合作共赢。对于市场需求大于此阈值,或者电商平台收取佣金率低于此阈值的商品,由于第三方物流企业能为电子零售商提供更高水平的物流服务和收取更低的物流费用,此时电子零售商会使用第三方物流企业的物流服务,而电商平台会通过调整佣金率提高自身利润。     

跨境物流联盟稳定性研究

为解决跨境物流联盟稳定性不高,效率低下等问题,对跨境物流联盟特征及稳定性因素进行分析,以构建联盟稳定性的演化博弈模型,分析跨境物流联盟内企业的演化稳定策略及稳定路径,并结合系统动力学仿真分析不同影响因素对联盟稳定性的影响。研究表明：联盟利益分配机制、成员企业投入的物流资源规模、组织成本对提升联盟稳定性有显著影响;而联盟运作效率、企业机会主义及合作协同度对提升联盟稳定性影响相对较弱。并据此提出增强跨境物流联盟稳定性的建议。     

二维平面网格上移动成本群体合作行为研究

从移动成本、收益期望与空间博弈的角度,探讨多主体系统的博弈策略演化与系统涌现特征之间的关系。利用空间演化博弈理论,构建了基于个体移动机制的拓扑结构时刻演变的空间演化博弈模型,分析了当主体具有不同的移动成本与收益期望时系统演化的稳定策略,通过分析稳定策略深入探讨系统中合作簇涌现的机理。仿真结果表明,提高移动成本能够最有效地促进系统合作率,同时中等水平的个体收益期望会进一步促进高移动成本的影响效果。     

基于Moran过程的竞争性舆情信息的网络传播博弈模型

新的媒体环境下,在享受不同形式在线社交网络提供便捷信息互动渠道的同时,需要加强对信息传播的管理与引导,防止其发展成为负面舆情信息肆意滋生的温床。结合传统演化博弈论与复杂网络理论,提出了竞争性舆情信息的网络传播博弈模型,并理论分析了正面舆情信息传播占优的收益条件及群体规模;随后,结合实际案例,通过仿真实验对比分析三种博弈环境下网络舆情的演化特征。三种博弈环境下,正面舆情信息传播策略占优条件均与收益有关,弱选择情境对收益参数的要求最为严格;强、弱选择情景下策略占优的条件还与群体规模有关,且强选择情景对群体规模的要求更为严格。     

有限博弈的矩阵半张量积方法

矩阵半张量积被广泛地应用在有限博弈的研究中,例如:1)演化博弈; 2)势博弈; 3)有限博弈的向量空间分解; 4)基于势博弈的优化与控制; 5)合作博弈等.本文的目的,就是对上述各种应用做一个全面的介绍,包括其原理、主要成果、以及尚待解决的问题.     

Cooperation in the evolutionary iterated prisoner’s dilemma game with risk attitude adaptation

The Iterated Prisoner’s Dilemma (IPD) game has been commonly used to investigate the cooperation among competitors. However, most previous studies on the IPD focused solely on maximizing players’ average payoffs without considering their risk preferences. By introducing the concept of income stream risk into the IPD game, this paper presents a novel evolutionary IPD model with agents seeking to balance between average payoffs and risks with respect to their own risk attitudes. We build a new IPD model of multiple agents, in which agents interact with one another in the pair-wise IPD game while adapting their risk attitudes according to their received payoffs. Agents become more risk averse after their payoffs exceed their aspirations, or become more risk seeking after their payoffs fall short of their aspirations. The aspiration levels of agents are determined based on their historical self-payoff information or the payoff information of the agent population. Simulations are conducted to investigate the emergence of cooperation under these two comparison methods. Results indicate that agents can sustain a highly cooperative equilibrium when they consider only their own historical payoffs as aspirations (called historical comparison) in adjusting their risk attitudes. This holds true even for the IPD with a short game encounter, for which cooperation was previously demonstrated difficult. However, when agents evaluate their payoffs in comparison with the population average payoff (called social comparison), those agents with payoffs below the population average tend to be dissatisfied with the game outcomes. This dissatisfaction will induce more risk-seeking behavior of agents in the IPD game, which will constitute a strong deterrent to the emergence of mutual cooperation in the population.