>>115 つづき

ついでに
これも文字化けを修正する気が無いので、原文を
http://math.stackexchange.com/questions/1430439/how-to-show-that-the-event-that-a-prisoner-does-no-go-free-is-not-measurable
probability theory - How to show that the event that a prisoner does no go free is not measurable - Mathematics Stack Exchange: asked Sep 11 '15 at 4:07
(抜粋)
I was reading this webpage a few months ago about the following problem-

A countable infinite number of prisoners are placed on the natural numbers, facing in the positive direction (ie, everyone can see an infinite number of prisoners).
Hats will be placed and each prisoner will be asked what his hat color is. However, to complicate things, prisoners cannot hear previous guesses or whether they were correct. In this new situation, what is the best strategy?

(I won't link the best strategy in case someone wants to give it a go but note that my question is about the solution)

and I recall my friend and I were trying to come up with a formal argument for why the probability is ill-defined. We kept going in circles so we left it in the end.
つづく