Subject: Four Color Maps<br/>
Date: Dec 05, 2003 @ 20:22<br/>
Author: Eric Choate (&quot;Eric Choate&quot; &lt;choatune@...&gt;)<br/>
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<div id="ygrps-yiv-1453376542">The presence of the Azerbaijani exclave (and many others) means that <br/>
the present set of national boundaries on earth does not satisfy the <br/>
prerequesites to apply the Four Color Theorem.  Nevertheless, a four <br/>
color map of the Caucasus can still be made.  It&#39;s just that it&#39;s <br/>
possible to draw borders with exclaves that do make it impossible to <br/>
color countries with only four colors.<br/>
<br/>
But there are national exclaves that I am unaware of.  Most would be <br/>
small enough that they would be omitted on a world map that is of a <br/>
size that I could find.  Does anyone know of an exclave that if it <br/>
were included would force more than four colors?  <br/>
<br/>
Similarly, I&#39;m not that familiar with the <br/>
states/provinces/cantons/oblasts/etc., of every country.  is there a <br/>
country that cannot produce a four-color map of its political <br/>
subdivisions?  <br/>
<br/>
What about US states with counties?  Or I&#39;m sure with all the <br/>
gerrymandering in state legislatures, a congressional district map <br/>
somewhere needs a fifth color.  Anyone know of one?<br/>
<br/>
eric</div>