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From: sharp@farmer.DEC
Newsgroups: net.math
Subject: Re: Dot Town, USA
Message-ID: <3488@decwrl.UUCP>
Date: Thu, 30-Aug-84 15:18:26 EDT
Article-I.D.: decwrl.3488
Posted: Thu Aug 30 15:18:26 1984
Date-Received: Sat, 1-Sep-84 09:21:12 EDT
Sender: daemon@decwrl.UUCP
Organization: DEC Engineering Network
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What happens is that if n people in Dot Town have blue dots those people
commit suicide on the n'th day, and all the rest of the people commit
suicide on the n+1'th day.

Once the stranger announces that at least one person has a blue dot then:

If only one person has a blue dot, that person sees no blue dots, so he or
she knows that she's the one with the blue dot. He or she then commits
suicide on day 1.

If two people have blue dots, then they each see one person with a blue dot.
When they see that same person again on day 2, knowing what that person's
logical behavior would be if there was only one blue dot, they realize that
they both have blue dots, and so commit suicide on day 2.

If three people have blue dots, they each see two people, and reasoning as
above they realize on day 3 that they each have blue dots.

Et cetera, up to day n.

Of course on day n+1 all the red dot people follow suit.