In Aumann’s original paper, the statement of the theorem doesn’t involve any assumption that the two parties have performed any sort of iterative procedure. In informal explanations of why the result makes sense, such iterative procedures are usually described. I think this illustrates the point that the innocuous-sounding description of what the two parties are supposed to know (“their posteriors are common knowledge”) conceals more than meets the eye: to get a situation where anything like it is true, you need to assume that they’ve been through some higher-quality information exchange procedure.
The proof looks at an ordering of posteriors p1, p2, etc, that result from subsequent levels of knowledge of knowledge of the other’s posteriors. However, these are shown to be equal, so in a sense all of the iterations happens in some way simultaneously. -- Actually, I looked at it again and I’m not so sure this is true. It’s how I understand it.
In Aumann’s original paper, the statement of the theorem doesn’t involve any assumption that the two parties have performed any sort of iterative procedure. In informal explanations of why the result makes sense, such iterative procedures are usually described. I think this illustrates the point that the innocuous-sounding description of what the two parties are supposed to know (“their posteriors are common knowledge”) conceals more than meets the eye: to get a situation where anything like it is true, you need to assume that they’ve been through some higher-quality information exchange procedure.
The proof looks at an ordering of posteriors p1, p2, etc, that result from subsequent levels of knowledge of knowledge of the other’s posteriors. However, these are shown to be equal, so in a sense all of the iterations happens in some way simultaneously. -- Actually, I looked at it again and I’m not so sure this is true. It’s how I understand it.