Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 beta 3/9/83; site sdcrdcf.UUCP Path: utzoo!watmath!clyde!burl!ulysses!unc!mcnc!decvax!ittvax!dcdwest!sdcsvax!sdcrdcf!markb From: markb@sdcrdcf.UUCP Newsgroups: net.math Subject: Re: Dot Town, U.S.A. Message-ID: <1277@sdcrdcf.UUCP> Date: Wed, 29-Aug-84 10:24:36 EDT Article-I.D.: sdcrdcf.1277 Posted: Wed Aug 29 10:24:36 1984 Date-Received: Fri, 31-Aug-84 03:20:49 EDT References: <2479@hplabsb.UUCP> Reply-To: markb@sdcrdcf.UUCP (Mark Biggar) Organization: System Development Corporation, Santa Monica Lines: 27 Summary: In article halle1@houxz.UUCP (J.HALLE) writes: >Or perhaps he wasn't lying. Either there was exactly one blue dot, in >which case everyone dies within 2 days, or there were 2 or more, in which >case things go on like before. Not true. If there are 2 blue dots, then most people see 2 blue dots and just 2 people see 1 blue dot. Each of those 2 people notice that the other does not commit suicide on the first evening, therefore they now know that the other must see a blue dot on their own back and commit suicide on the second day and everyone else dies then next day. With 3 blue dots they each reson that the 2 people they see with blue dots can have the only blue dots after 2 days with no deaths, and commit suicide on the 3rd day. Generalizing, with n blue dots all people with blue dots dies on day n followed by everyone else on the next day. The interesting case is if everyone has (and therefore sees) only red dots. Why should you believe the stranger? You have no evidence that he told the truth (if you see a blue dot he had to have told the truth). Because there is no condition stated in the problem claiming that the Dotians always believe what strangers tell them. Whether or not everyone dies now depends on the probability that someone believes the stranger. Mark Biggar {allegra,burdvax,cbosgd,hplabs,ihnp4,akgua,sdcsvax}!sdcrdcf!markb