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From: graham@convex.UUCP
Newsgroups: net.puzzle
Subject: Re: Don't cross my path ! - (nf)
Message-ID: <50900001@convex.UUCP>
Date: Thu, 16-Aug-84 11:14:00 EDT
Article-I.D.: convex.50900001
Posted: Thu Aug 16 11:14:00 1984
Date-Received: Sat, 18-Aug-84 01:47:45 EDT
References: <785@abnjh.UUCP>
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Nf-ID: #R:abnjh:-78500:convex:50900001:000:731
Nf-From: convex!graham    Aug 16 10:14:00 1984

#R:abnjh:-78500:convex:50900001:000:731
convex!graham    Aug 16 10:14:00 1984

There are 3 men living in 3 seperate houses within a fenced in courtyard.
Following a particulary vicious argument over a gardenhose, they made
up their minds never to cross each others paths again.  This seemed
like a good idea at the time (considering the heated debate over gun
control :-) ), however, they all had to go to work at the same time of
the morning.  They settled on this: ...

This seems to be the same as the three houses, three tanks (water, gas, oil)
problem: run pipes from all tanks to all houses without crossing pipes.
I believe that planar graph theory can be used to show that it is impossible,
though I can't give the proof.

Marv Graham; Convex Computer Corp. {allegra,ihnp4,uiucdcs,ctvax}!convex!graham