标题： 常识，重新获得 显示英文标题

标题： Common Knowledge, Regained

摘要： 为了在动态环境中出现共同知识，所有参与者必须同时知道它已经出现。 因此，在存在时间摩擦的许多现实环境中，共同知识无法出现。 Halpern 和 Moses（1990）的这一反直觉观察被 Arrow 等人（1987）和 Aumann（1989）讨论过，被 Morris（2014）称为一个悖论，并且在过去四十年中一直未能得到令人满意的解决。 我们通过提出共同知识的新定义来解决这一悖论，该定义在静态环境中与传统定义一致，但在动态环境中更为宽松。 根据我们的定义，共同知识可以在没有同时性的情况下出现，尤其是在 Haplern-Moses 悖论的经典例子中。 我们通过为其推导出一个类似 Aumann（1976）的共识定理，证明了其有效性，展示了它在添加了时间摩擦的 Geanakoplos 和 Polemarchakis（1982）环境中出现，并将其应用于描述动态协调博弈中的均衡行为。 显示英文摘要

摘要： For common knowledge to arise in dynamic settings, all players must simultaneously come to know it has arisen. Consequently, common knowledge cannot arise in many realistic settings with timing frictions. This counterintuitive observation of Halpern and Moses (1990) was discussed by Arrow et al. (1987) and Aumann (1989), was called a paradox by Morris (2014), and has evaded satisfactory resolution for four decades. We resolve this paradox by proposing a new definition for common knowledge, which coincides with the traditional one in static settings but is more permissive in dynamic settings. Under our definition, common knowledge can arise without simultaneity, particularly in canonical examples of the Haplern-Moses paradox. We demonstrate its usefulness by deriving for it an agreement theorem \`a la Aumann (1976), showing it arises in the setting of Geanakoplos and Polemarchakis (1982) with timing frictions added, and applying it to characterize equilibrium behavior in a dynamic coordination game.