[extropy-chat] Re: monty hall paradox again: reds and green gorfs

Alejandro Dubrovsky alito at organicrobot.com
Fri May 21 21:46:09 UTC 2004


On Fri, 2004-05-21 at 11:35 -0700, "Hal Finney" wrote:

> If you change the rules to say that there could be any value in the
> envelope less than one billion dollars, then the correct strategy is
> to switch if the value you see is less than half a billion, else don't
> switch.  This is simple and logical and no one will disagree with it.

*Raises hand* I do.  The problem is not so easily dealt with.  I was
thinking of doing a simulation today until i realised the ridiculousness
of what i was about to program:
two agents,  two envelopes.   both get the same envelope (50:50
probability of getting each envelope), but now one agent sits, and one
swaps.
ie, summarised:
Agent1 = Envelope1
Agent2 = Envelope2

There's no way that this can lead to any difference between the agents'
outcome (unless some magic happens when i first assign Envelope1 to
Agent2 and then set it to Envelope2).

Sticking or swaping makes no difference.  The hard bit is how to get rid
of the double or half argument after opening the first one.  Probability
of holding the bigger envelope then seems to get modified to 2/3 as soon
as you open it.  How!?

alejandro






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