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arXiv 0802.1604cs.GTcs.MA
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关于图对策Nash均衡的复杂性

On the Complexity of Nash Equilibria of Action-Graph Games

Constantinos Daskalakis, Grant Schoenebeck, Gregory Valiant, Paul Valiant

摘要:

研究了行动图博弈的纳什均衡问题。由Bhat和Leyton-Brown引入的AGG是一种简洁的游戏表示,它既包含了图形游戏中的“局部”依赖性,又包含了匿名游戏中对其他代理身份的部分冷漠,这在许多自然环境中都有发生。这是通过在动作集上指定一个图来实现的,这样一个代理选择策略的回报只取决于动作图中每个相邻策略的代理数量。我们提出了一个多项式时间近似计划计算混合纳什均衡AGG与恒定的树宽和代理类型(和任意数量的战略),连同硬度结果的情况下,树宽或代理类型的数量是不受约束的。特别是,我们表明,即使动作图是一棵树,但代理类型的数量是不受约束的,它是NP-完全的,以决定存在一个纯策略纳什均衡和PPAD-完全计算混合纳什均衡(即使是近似的);同样的对称AGG(所有代理属于一个单一的类型),如果我们允许任意的树宽。这些硬度结果表明,在某种意义上,我们的PTAS是一个积极的结果,因为人们可以预期的强大。

英文摘要:

We consider the problem of computing Nash Equilibria of action-graph games (AGGs). AGGs, introduced by Bhat and Leyton-Brown, is a succinct representation of games that encapsulates both "local" dependencies as in graphical games, and partial indifference to other agents' identities as in anonymous games, which occur in many natural settings. This is achieved by specifying a graph on the set of actions, so that the payoff of an agent for selecting a strategy depends only on the number of agents playing each of the neighboring strategies in the action graph. We present a Polynomial Time Approximation Scheme for computing mixed Nash equilibria of AGGs with constant treewidth and a constant number of agent types (and an arbitrary number of strategies), together with hardness results for the cases when either the treewidth or the number of agent types is unconstrained. In particular, we show that even if the action graph is a tree, but the number of agent-types is unconstrained, it is NP-complete to decide the existence of a pure-strategy Nash equilibrium and PPAD-complete to compute a mixed Nash equilibrium (even an approximate one); similarly for symmetric AGGs (all agents belong to a single type), if we allow arbitrary treewidth. These hardness results suggest that, in some sense, our PTAS is as strong of a positive result as one can expect.

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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