>>445 補足 DR Pruss氏は、mathoverflowの回答で、下記を述べている 即ち、「the function is measurable.」ならば 良いが、そうでないときは、ダメだという 実際、コイントス(=coin flips)で、Ω={0,1}^Nなのに、実数の数列の同値類と代表なら、”guess π”とかなって それって、”Intuitively this seems a really dumb strategy. ”じゃんと、DR Pruss氏は いう (^^;
(参考) https://mathoverflow.net/questions/151286/probabilities-in-a-riddle-involving-axiom-of-choice Probabilities in a riddle involving axiom of choice Denis氏 Dec 9 '13 DR Pruss氏 (抜粋) Here's an amusing thing that may help see how measurability enters into these things. Consider a single sequence of infinitely many independent fair coin flips. Our state space is Ω={0,1}^N, corresponding to an infinite sequence (Xi)^∞ i=0 of i.i.d.r.v.s with P(Xi=1)=P(Xi=0)=1/2.
That's a fine argument assuming the function is measurable. If so, then guess according to the representative. If not, then guess π. (Yes, I realize that π not∈{0,1}.) Intuitively this seems a really dumb strategy.