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arXiv 1507.01191cs.GT
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什么时候可以在重复博弈中使用有限随机性?

When Can Limited Randomness Be Used in Repeated Games?

Pavel Hubáček, Moni Naor, Jonathan Ullman

摘要:

经典博弈论的中心结论是,只要允许参与者使用随机(混合)策略,每个有限范式博弈都有一个纳什均衡。然而,在实践中,已知人类不善于生成类随机序列,并且真正的随机比特可能不可用。即使玩家可以访问游戏的单个实例的足够的随机位,如果游戏被玩很多次,他们的随机性可能是不够的。在这项工作中,我们问是否随机性是必要的均衡存在于重复的游戏。我们发现,对于一个大类的游戏包含任意两个玩家零和游戏,近似纳什均衡的$n$阶段重复版本的游戏存在的当且仅当两个玩家有$Ω(n)$随机位。相比之下,我们发现,存在一类游戏,其中没有平衡存在于纯策略,但$n$阶段重复版本的游戏有一个确切的纳什均衡,其中每个玩家只使用一个常数的随机位。当参与者被假设为计算上有界时,如果密码伪随机发生器(或等价地,单向函数)存在,那么参与者可以将他们的策略基于仅从少量真正随机位导出的“类随机”序列。我们表明,相比之下,在重复的两个玩家零和游戏,如果伪随机发生器\emph{do not}存在,那么$Ω(n)$随机位仍然是必要的均衡存在。

英文摘要:

The central result of classical game theory states that every finite normal form game has a Nash equilibrium, provided that players are allowed to use randomized (mixed) strategies. However, in practice, humans are known to be bad at generating random-like sequences, and true random bits may be unavailable. Even if the players have access to enough random bits for a single instance of the game their randomness might be insufficient if the game is played many times. In this work, we ask whether randomness is necessary for equilibria to exist in finitely repeated games. We show that for a large class of games containing arbitrary two-player zero-sum games, approximate Nash equilibria of the $n$-stage repeated version of the game exist if and only if both players have $Ω(n)$ random bits. In contrast, we show that there exists a class of games for which no equilibrium exists in pure strategies, yet the $n$-stage repeated version of the game has an exact Nash equilibrium in which each player uses only a constant number of random bits. When the players are assumed to be computationally bounded, if cryptographic pseudorandom generators (or, equivalently, one-way functions) exist, then the players can base their strategies on "random-like" sequences derived from only a small number of truly random bits. We show that, in contrast, in repeated two-player zero-sum games, if pseudorandom generators \emph{do not} exist, then $Ω(n)$ random bits remain necessary for equilibria to exist.

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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