I still have no clue how Thrun's method could be correct in the ideal case. He's relying on having some clue as to how much money there is in the envelopes.
Here's a restatement of the problem that makes my objection clearer:
"Hi again."
"Omega, my pal! Thanks for the million dollars. That was pretty sweet."
"I've got another offer for you, my fairy AI-son. Here is a box with some amount of Gxnthrzian currency. It's yours if you do one little thing for me."
"Umm. How could I spend that?"
"They will make contact with Earth in two weeks. It'll be awesome. Anyway, so that little thing - here's a document. Sort of a Gxnthrzian IOU. Just scratch one of those two circles, and the box is yours. And don't squint - you can't actually read it with your current technology level, and of course it's in an alien language you don't know."
I take the circular sheet of plastic, but say, "Waaait. How much is the IOU for?"
"The IOU is for one third as much as money in the box. I'll handle the payment for you - no fee."
I turn the circle around and arbitrarily select one of the circles.
Omega interrupts me from scratching it. "If you pick that circle, then after the IOU is paid, you will have a grand total of one Atrazad, fifteen thousand Joks, and two Libgurs."
"Well, what if I check the other one?"
"Sore wa himitsu desu!"
I still have no clue how Thrun's method could be correct in the ideal case. He's relying on having some clue as to how much money there is in the envelopes.
The following is an elementary Bayesian analysis of why (a de-randomized version of) Thrun's method works. Does this not include the "ideal case" for some reason?
Let A and B be two fixed, but unknown-to-you, numbers. Let Z be a third number. (You may suppose that Z is known or unknown, random or not; it doesn't matter.) Assume that, so far as your state of knowledge is concerned,
A an
Today's post, The Rhythm of Disagreement was originally published on 01 June 2008. A summary (taken from the LW wiki):
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