four colour map theorem
<mathematics, application> (Or "four colour theorem") The theorem stating
that if the plane is divided into connected regions which are to be coloured so
that no two adjacent regions have the same colour (as when colouring countries
on a map of the world), it is never necessary to use more than four colours.
The proof, due to Appel and Haken, attained notoriety by using a computer to
check tens of thousands of cases and is thus not humanly checkable, even in
principle. Some thought that this brought the philosophical status of the proof
There are now rumours of a simpler proof, not requiring the use of a computer.
See also chromatic number
foundation « FOundation for Research and Technology
- Hellas « four-colour glossies « four colour map
theorem » four colour theorem » Fourier
transform » fourth generation computer