Discreet investors exert greater influence on cooperation in the public goods game

This paper studies the evolutionary process of cooperative behavior in a public goods game model with heterogeneous investment strategies in square lattices.In the proposed model,players are divided into defectors,cooperators and discreet investors.Among these,defectors do not participate in investing,discreet investors make heterogeneous investments based on the investment behavior and cooperation value of their neighbors,and cooperators invest equally in each neighbor.In real life,heterogeneous investment is often accompanied by time or economic costs.The discreet investors in this paper pay a certain price to obtain their neighbors'investment behavior and cooperation value,which quantifies the time and economic costs of the heterogeneous investment process.The results of Monte Carlo simulation experiments in this study show that discreet investors can effectively resist the invasion of the defectors,form a stable cooperative group and expand the cooperative advantage in evolution.However,when discreet investors pay too high a price,they lose their strategic advantage.The results in this paper help us understand the role of heterogeneous investment in promoting and maintaining human social cooperation.

Strategy dominance mechanism of autonomous collaboration in unmanned swarm within the framework of public goods game

The key advantage of unmanned swarm operation is its autonomous cooperation. How to improve the proportion of cooperators is one of the key issues of autonomous collaboration in unmanned swarm operations. This work proposes a strategy dominance mechanism of autonomous collaboration in unmanned swarm within the framework of public goods game. It starts with the requirement analysis of autonomous collaboration in unmanned swarm;and an aspiration-driven multiplayer evolutionary game model is established based on the requirement. Then the average abundance function and strategy dominance condition of the model are constructed by theoretical derivation. Furthermore, the evolutionary mechanism of parameter adjustment in swarm cooperation is revealed via simulation,and the influences of the multiplication factor r, aspiration levelα, threshold m and other parameters on the strategy dominance conditions were simulated for both linear and threshold public goods games(PGGs) to determine the strategy dominance characteristics;Finally, deliberate proposals are suggested to provide a meaningful exploration in the actual control of unmanned swarm cooperation.

Maintenance of cooperation induced by punishment in public goods games

In this paper, we study the public goods games with punishment by adopting the well-known approximate best response dynamics. It shows that the evolution of cooperation is affected by two aspects when other parameters are fixed. One is the punishment mechanism which can avoid the dilemma of lacking investment, and the other is the degree of rationality. Theoretical analysis and numerical results indicate that the existence of punishment mechanism and distribution of rationality are the keys to the enhancement of cooperation level. We also testify that they can heavily influence the payoffs of system as well. The findings in this paper may provide a deeper understanding of some social dilemmas.

Stochastic evolutionary public goods game with first and second order costly punishments in finite populations

We study the stochastic evolutionary public goods game with punishment in a finite size population. Two kinds of costly punishments are considered, i.e., first-order punishment in which only the defectors are punished, and second-order punishment in which both the defectors and the cooperators who do not punish the defective behaviors are punished. We focus on the stochastic stable equilibrium of the system. In the population, the evolutionary process of strategies is described as a finite state Markov process. The evolutionary equilibrium of the system and its stochastic stability are analyzed by the limit distribution of the Markov process. By numerical experiments, our findings are as follows.（i） The first-order costly punishment can change the evolutionary dynamics and equilibrium of the public goods game, and it can promote cooperation only when both the intensity of punishment and the return on investment parameters are large enough.（ii）Under the first-order punishment, the further imposition of the second-order punishment cannot change the evolutionary dynamics of the system dramatically, but can only change the probability of the system to select the equilibrium points in the ＂C＋P＂ states, which refer to the co-existence states of cooperation and punishment. The second-order punishment has limited roles in promoting cooperation, except for some critical combinations of parameters.（iii） When the system chooses＂C＋P＂ states with probability one, the increase of the punishment probability under second-order punishment will further increase the proportion of the ＂P＂ strategy in the ＂C＋P＂ states.

Punishment in optional public goods games

In this work, the optional public goods games with punishment are studied. By adopting the approximate best response dynamics, a micro model is given to explain the evolutionary process. Simultaneously, the magnitude of rationality is also considered. Under the condition of bounded rationality which provides a light to interpret phenomena in human society, the model leads to two types of equilibriums. One is the equilibrium without punishers and the other is the equilibrium including only punishers and cooperators. In addition, the effects of rationality on equilibriums are briefly investigated.

Evolution of Cooperation in Public Goods Games

We investigate the evolution of cooperation with evolutionary public goods games based on finite populations, where four pure strategies： cooperators, defectors, punishers and loners who are unwilling to participate are considered. By adopting approximate best response dynamics, we show that the magnitude of rationality not only quantitatively explains the experiment results in [Nature （London） 425 （2003） 390], but also it will heavily influence the evolution of cooperation. Compared with previous results of infinite populations, which result in two equilibriums, we show that there merely exists a special equilibrium cooperation. In addition, we characterize that loner＇s and the relevant high value of bounded rationality will sustain payoff plays an active role in the maintenance of cooperation, which will only be warranted for the low and moderate values of loner＇s payoff. It thus indicates the effects of rationality and loner＇s payoff will influence the cooperation. Finally, we highlight the important result that the introduction of voluntary participation and punishment will facilitate cooperation greatly.

Fitness of others'evaluation effect promotes cooperation in spatial public goods game

Payoff-driven strategy updating rule has always been adopted as a classic mechanism,but up to now,there have been a great many of researches on considering other forms of strategy updating rules,among which pursuing high fitness is one of the most direct and conventional motivations in the decision-making using game theory.But there are few or no researches on fitness from the perspective of others'evaluation.In view of this,we propose a new model in which the evaluation effect with fitness-driven strategy updating rule is taken into consideration,and introduce an evaluation coefficient to present the degree of others'evaluation on individual's behavior.The cooperative individuals can get positive evaluation,otherwise defective individuals get negative evaluation,and the degree of evaluation is related to the number of neighbors who have the same strategy of individual.Through numerical simulation,we find that the evaluation effect of others can enhance the network reciprocity,thus promoting the cooperation.For a strong dilemma,the higher evaluation coefficient can greatly weaken the cooperation dilemma;for a weak one,the higher evaluation coefficient can make cooperator clusters spread faster,however,there is no significant difference in the level of cooperation in the final stable state among different evaluation coefficients.The cooperation becomes more flourish as the number of fitness-driven individuals increases,when all individuals adopt fitness-driven strategy updating rule,the cooperators can quickly occupy the whole population.Besides,we demonstrate the robustness of the results on the WS small-world network,ER random network,and BA scalefree network.

EVOLUTIONARY PUBLIC GOODS GAMES BASED ON HISTORICAL PAYOFFS

We investigate the evolution of cooperation in public goods game based on individuals' historical payoffs. In particular, the fitness of individuals are characterized by two types of payoffs, which are obtained by acting as cooperators and defectors, respectively. Both of payoffs are the linear combination of the current payoffs and the cumulative historical payoffs. The results show that cooperation is enhanced by an increasing memory effect with a wide range of related factors. To explain this phenomenon, we plot some representative snapshots of the population and scrutinize the mean fitness of cooperators and defectors along the boundary. It is found that increasing memory effect induces a positive feedback mechanism for cooperators to expand their districts. Defectors can just survive through forming narrower clusters to exploit cooperators more widely. The threshold values for cooperators and defectors vanishing under the influence of noise are also investigated.

行政诉讼中公序良俗原则之适用

公序良俗原则在行政诉讼中的适用边界具有模糊性。通过NVivo质性分析可得出,近年来在行政诉讼中适用公序良俗原则的案件数量增加,案件类型的范围显著扩张。对法院、原告与被告就该原则的判断标准或描述性方式及其裁判文书中位置梳理可得出,不同法官对公序良俗原则的判断标准不同,当事人对该原则也有不同的理解。公序良俗原则判断标准的不确定性成因,一是法院对该原则的论述理由不具有说服力,应适当考虑行政诉讼当事人的描述性方式,并对此予以适当回应;二是法官缺乏将原则具体化的思维工具,宜通过“比附”和“还原”方式厘清公序良俗原则的适用边界,进而搭建起适用公序良俗原则及其新规则的路径。

基于网络环境的若干组合优化博弈问题研究

随着互联网技术的飞速发展和社交网络的广泛普及,大量现实问题可以模型化为基于网络环境的组合优化问题,受到学术界和工业界的广泛关注。在这一过程中,参与者通常受到个人利益的驱动,采取策略性行动以实现自身效用的最大化。这种以“自利”为核心的行为模式,不仅对其他参与者产生影响,同时所有参与者的策略选择共同决定了社会福利整体目标的实现。在此背景下,参与者之间的互动呈现出合作与竞争并存的复杂局面,构成了组合优化博弈问题。本文旨在深入分析基于网络环境的三类具有挑战性的组合优化博弈问题:网络上的公共品博弈、网络上的点覆盖博弈以及网络上的路由博弈。这三类问题不仅在组合优化和理论计算机科学领域占据着举足轻重的地位,而且在管理科学与工程、经济学等多个交叉学科领域中也展现出广泛的应用前景。因此,本文将系统性地介绍这三类组合优化博弈问题,并对其最新的研究进展进行详细的梳理和深入的凝练,以期为相关领域的研究者和实践者提供有价值的参考和启示。

在线慈善众筹中匹配捐款的动态影响:理论与实证

在线众筹平台可以利用网络汇聚慈善性捐助以辅助公益性项目融资,近年来得到了长足发展,获得了社会的普遍关注,在基于社会协调机制的“第三次分配”的实践中起到了积极推动作用。在线慈善众筹过程中,平台可以借助企业和基金会的大额捐款对个人捐款进行匹配,即匹配捐款机制。匹配捐款能否有效刺激个人捐款,是一个值得探讨的重要问题。一方面,经典的公共品理论指出,公共品的非排他性导致个人捐助者有“搭便车”的动机,企业的匹配捐款会“挤出”个人捐款。另一方面,动态公共品博弈产生的“跨时策略互补”效应会激发个体多捐助。本文采用一个离散公共品的动态自发供给模型来分析匹配捐款如何影响个人捐款额。模型分析显示,在“搭便车”动机与“跨时策略互补”效应的共同作用下,匹配捐款是否产生“挤出”效应取决于公益项目是否具有较高的内在质量。项目质量较高时,即达成目标筹款金额的内生预期时间较短时,则匹配捐款可以提升个人捐款额。本研究利用慈善众筹网站Kiva的项目捐款微观数据,建立预测模型和构造项目质量的动态测量。实证分析结果支持基于理论模型分析得到的假说。

基于公共品博弈的无人机集群自主协同机制

无人机集群自主协同作战是未来战争的重要作战样式,自主协同机制研究有利于揭示无人机集群协同形成与演化规律,为无人机集群作战应用提供理论支撑。首先构建无人机集群信息交互网络,定义基于拓扑势的无人机交互等级。通过分析无人机集群自主协同与演化博弈的映射关系,建立基于公共品博弈的无人机集群演化博弈模型,设计基于交互等级的无人机集群总体期望收益函数、平均期望收益函数和愿景更新动态策略更新机制。利用马尔可夫链定量描述无人机集群演化过程,并理论推导了表征无人机集群演化博弈平稳分布的平均丰度函数。通过仿真验证基于公共品博弈的无人机集群自主协同机制的可行性和有效性,并分析选择强度、交互收益系数、增益因子与愿景水平等参数变化对无人机集群协同行为的影响,为无人机集群自主协同参数调控设计提供理论支持。研究结果表明:所提自主协同机制相较于提供点机制、惩罚机制能更大程度促进无人机集群合作涌现,为无人机集群自主协同理论向作战应用提供技术支持。

不完全契约下政府实施公共品负担对私人部门行为选择影响机制研究

政府部门往往会承担公共品负担提高社会公共福利和满足社会诉求,私人部门在PPP项目建设运营中会采取机会主义行为损害政府部门利益和降低社会福利。本文运用演化博弈分析私人部门的机会主义行为演化机制。通过模型分析可得,当政府补贴系数低于一定程度时,私人部门采取机会主义行为的概率随着公共品负担强度的增加而增加;当政府实施公共品负担小于一定强度时,私人部门会随着政府补贴程度提高而不采取机会主义行为,而当公共品负担强度大于一定值时,政府补贴政策正相关性就被严重削弱;私人部门占据更多的利益分配比重,更有倾向采取机会主义行为。根据研究结果,政府部门应增强契约精神,公共品负担下,政府补贴并不能有效降低机会主义行为,而应完善监管机制和提升私人部门对项目收益的信心。

带有异质性的国家间合作减排问题研究

基于《巴黎协定》中的自主贡献(intended nationally determined contributions)和全球盘点(global stocktake)机制,建立了带集体风险的多周期公共品博弈模型,应用子博弈精炼纳什均衡方法分析了当不同国家在禀赋、减排成本、气候风险等方面存在异质性时,能否及如何达成合作减排.研究发现,若所有国家气候风险的加权平均达到或者超过减排目标系数,则可以通过构造Grim策略使合作成为子博弈精炼纳什均衡,并且减排周期和国家数量的变化不会影响合作均衡的达成.

基于深度强化学习的无人机集群协同作战决策方法

在无人机(UAV)集群攻击地面目标时,UAV集群将分为两个编队:主攻目标的打击型UAV集群和牵制敌方的辅助型UAV集群。当辅助型UAV集群选择激进进攻或保存实力这两种动作策略时,任务场景类似于公共物品博弈,此时合作者的收益小于背叛者。基于此,提出一种基于深度强化学习的UAV集群协同作战决策方法。首先,通过建立基于公共物品博弈的UAV集群作战模型,模拟智能化UAV集群在合作中个体与集体间的利益冲突问题;其次,利用多智能体深度确定性策略梯度(MADDPG)算法求解辅助UAV集群最合理的作战决策,从而以最小的损耗代价实现集群胜利。在不同数量UAV情况下进行训练并展开实验,实验结果表明,与IDQN(Independent Deep QNetwork)和ID3QN(Imitative Dueling Double Deep Q-Network)这两种算法的训练效果相比,所提算法的收敛性最好,且在4架辅助型UAV情况下胜率可达100%,在其他UAV数情况下也明显优于对比算法。

基于公共物品博弈框架的排斥行为范式开发

已有的排斥者研究范式通常存在诱发效率不高的缺点。本研究结合公共物品博弈框架(PGG),开发了一个能够高效地引发排斥行为的实验范式,并用两个实验对该范式的有效性进行了检验。结果发现,被试对损害团体利益的成员均表现出高度的排斥行为:实验1中实验组被试的排斥诱发率显著高于对照组;实验2增加匿名/公开情境,发现实验组中,匿名条件下被试的排斥行为显著多于公开条件。结果表明,该范式能够稳定有效地诱发排斥行为,是排斥者研究的新方法。

Maintenance of cooperation in a public goods game:A new decision-making criterion with incomplete information

Hardin's "The Tragedy of the Commons" prophesies the inescapable collapse of many human enterprises.The emergence and abundance of cooperation in animal and human societies is a challenging puzzle to evolutionary theory.In this work,we introduce a new decision-making criterion into a voluntary public goods game with incomplete information and choose successful strategies according to previous payoffs for a certain strategy as well as the risk-averse benefit.We find that the interest rate of the common pool and the magnitude of memory have crucial effects on the average welfare of the population.The appropriate sense of individuals' innovation also substantially influences the equilibrium strategies distribution in the long run.

Punishment Mechanism with Self-Adjusting Rules in Spatial Voluntary Public Goods Games

The phenomena of cooperation in animal and human society are ubiquitous, but the selfish outcome that no player contributes to the public good will lead to the "tragedy of the commons". The recent research shows that high punishment can improve the cooperation of the population. In this paper, we introduce a punishment mechanism into spatial voluntary public goods games with every individual only knowing his own payoff in each round. Using the self-adjusting rules, we find that the different cost for punishment can lead to different effects on the voluntary public goods games. Especially, when the cost for punishment is decreased, a higher contribution region will appear in the case of low r value. It means even for the low r value, individuals can form the contributing groups in large quantities to produce a more efficient outcome than that in moderate r value. In addition, we also find the players' memory can have effects on the average outcome of the population.

Emergence of Group Cooperation in Public Goods Game on Regular Small-World Network

The regular small-world network, which contains the properties of small-world network and regular network, has recently received substantial attention and has been applied in researches on 2-person games. However, it is a common phenomenon that cooperation always appears as a group behavior. In order to investigate the mechanism of group cooperation, we propose an evolutionary multi-person game model on a regular small-world network based on public goods game theory. Then, to make a comparison of frequency of cooperation among different networks, we carry out simulations on three kinds of networks with the same configuration of average degree： the square lattice, regular small-world network and random regular network. The results of simulation show that the group cooperation will emerge among these three networks when the enhancement factor r exceeds a threshold. Furthermore, time required for full cooperation on regular small-world network is slightly longer than the other networks, which indicates that the compact interactions and random interactions will promote cooperation, while the longer-range links are the obstacles in the emergence of cooperation. In addition, the cooperation would be promoted further by enhancing the random interactions on regular small-world network.

“乐”于合作:感知社会善念诱导合作行为的情绪机制

基于两个仿真行为实验,考察了互动博弈中行为实施者的社会善念促进接受者合作行为的情绪机制。实验1采用"物品"选择游戏操控实施者的社会善念水平,结果发现:接受高社会善念行为的被试体验到更强的积极情绪和更弱的消极情绪,且愿意在随后的公共物品游戏中贡献更多的资源;其中,积极情绪在感知社会善念与合作行为间发挥着部分中介作用。实验2在实验1的基础上操纵被试在"纸牌"选择游戏中需要对手提供帮助的程度来设置自主性需要水平,进而揭示自主性需要在社会善念增强积极情绪体验中的内在机制,结果发现:除了证实实验1的结论外,积极情绪在感知社会善念与合作行为间发挥着完全中介作用;而自主性需要对感知社会善念—积极情绪关系起调节作用,即相比于低自主性需要,接受者的高自主性需要未得到满足时体验到的积极情绪更低。据此可认为,积极情绪体验是实施者的社会善念促进接受者合作行为的中介机制,而自主性需要的满足是获取积极情绪的根源。