Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site pur-ee.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxl!ihnp4!inuxc!pur-ee!ecn-ee!davy From: davy@ecn-ee.UUCP Newsgroups: net.ai Subject: Re: Re: Four color... - (nf) Message-ID: <1622@pur-ee.UUCP> Date: Wed, 22-Feb-84 17:19:00 EST Article-I.D.: pur-ee.1622 Posted: Wed Feb 22 17:19:00 1984 Date-Received: Fri, 24-Feb-84 01:40:18 EST Sender: notes@pur-ee.UUCP Organization: Electrical Engineering Department , Purdue University Lines: 31 #R:mit-eddi:-129000:ecn-ee:15300005:000:1121 ecn-ee!davy Feb 22 08:38:00 1984 Thanks to all who responded about my question of "what is the four color problem". For those of you who also don't know, a brief explanation (from sdcrdcf!darrelj) is: A long time conjecture in mathematics was that any planar map of regions (e.g. the United States minus anomalies like a two-piece Michigan) could be colored in such a way that every pair of regions which share a border are different color using no more than 4 distinct colors (also, sharing a single finite number of points only do NOT share a border). It was believed true for the last 100 years (and many erroneous proofs were offerred), until a few years ago, mathemeticians at U. of Illinois generated a proof, the short part of which said "all graphs without properties xxx can be four-colored, the long part of which was a computer generation of all the thousands of graphs with the messy properties combined with an enumeration of how to color each one. There are related kinds of problems for other topological surfaces such as the surface of a sphere and the surface of a torus (doughnut). --Dave Curry