arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1306.1849cs.GTcs.AIcs.MA
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关于战略均衡的新结果

New Results on Equilibria in Strategic Candidacy

Université Paris-Dauphine(巴黎第九大学);Université Pierre et Marie Curie(皮埃尔和玛丽·居里大学);University of Southampton(南安普顿大学)

Jérôme Lang, Nicolas Maudet, Maria Polukarov, Alice Cohen-Hadria

摘要:

我们考虑一种投票设置,候选人对选举结果有偏好,可以自由加入或退出选举。Dutta等人最初研究了相应的候选人资格博弈,其中候选人策略性地选择参与或不参与,他指出,没有一个满足随机性的非独裁投票程序是不受候选人策略影响的,也就是说,所有候选人参加选举的联合行动总是一个纯策略纳什均衡。Dutta等人还表明,对于某些投票树程序,存在没有纯纳什均衡的候选人博弈,并且对于通过连续淘汰输出复杂的投票获胜者的规则,所有博弈都有纯纳什均衡。其他投票规则没有结果。在这里,我们证明了几个这样的结果。对于四个候选人,我们得到的信息大致是,大多数评分规则(博尔达除外)都不能保证纯纳什均衡的存在,但对于奇数选民,孔多塞相容规则可以保证。对于五个候选人,我们研究的大多数规则不再有这种保证。最后,我们确定了一个突出的规则,保证存在一个纯纳什均衡的任何数量的候选人(和奇数选民):科普兰规则。我们还表明,在温和的假设下的投票规则,强均衡的存在性不能得到保证。

英文摘要:

We consider a voting setting where candidates have preferences about the outcome of the election and are free to join or leave the election. The corresponding candidacy game, where candidates choose strategically to participate or not, has been studied %initially by Dutta et al., who showed that no non-dictatorial voting procedure satisfying unanimity is candidacy-strategyproof, that is, is such that the joint action where all candidates enter the election is always a pure strategy Nash equilibrium. Dutta et al. also showed that for some voting tree procedures, there are candidacy games with no pure Nash equilibria, and that for the rule that outputs the sophisticated winner of voting by successive elimination, all games have a pure Nash equilibrium. No results were known about other voting rules. Here we prove several such results. For four candidates, the message is, roughly, that most scoring rules (with the exception of Borda) do not guarantee the existence of a pure Nash equilibrium but that Condorcet-consistent rules, for an odd number of voters, do. For five candidates, most rules we study no longer have this guarantee. Finally, we identify one prominent rule that guarantees the existence of a pure Nash equilibrium for any number of candidates (and for an odd number of voters): the Copeland rule. We also show that under mild assumptions on the voting rule, the existence of strong equilibria cannot be guaranteed.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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