Agreeing to agree
研究了在共同先验下，代理人能否就某个事件的后验概率达成一致，并给出了一个充要条件：存在一个非空有限事件F，使得在F中代理人无法区分事件E是否发生，且当F成为共同知识时该性质仍然成立。
Aumann has shown that agents who have a common prior cannot have common knowledge of their posteriors for event $E$ if these posteriors do not coincide. But given an event $E$, can the agents have posteriors with a common prior such that it is common knowledge that the posteriors for $E$ \\emph{do} coincide? We show that a necessary and sufficient condition for this is the existence of a nonempty \\emph{finite} event $F$ with the following two properties. First, it is common knowledge at $F$ that the agents cannot tell whether or not $E$ occurred. Second, this still holds true at $F$, when $F$ itself becomes common knowledge.