Postal Meter Strip Honoring the Solution of the Four Color Problem

Postal Meter Strip Honoring the Solution of the Four Color Problem

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Wolfgang Haken and Kenneth Appel’s proof of the four color problem was one of the first theorems published that required computers in its confirmation. The Englishman Francis Guthrie had conjectured in 1852 that four colors suffice to color any map drawn on a sheet of paper in such a way that countries sharing a common border are different colors. Heinrich Heesch showed in 1969 that the conjecture could be solved by considering a set of some 8,900 configurations with boundaries of up to eighteen edges. Haken and Appel, working with computer scientist John Koch, reduced the number of configurations examined to 1,936. For each case, their program that four colors sufficed to color it. When Appel and Haken announced their result, their employer, the University of Illinois mathematics department, altered its postal meter to print "Four Colors Suffice." This is such a postal meter stamp.
For a related computer printout, see 1999.0339.01.
Currently not on view
Object Name
Postal Meter Strip
Date made
September 30, 1976
Haken, Wolfgang
University of Illinois
place made
United States: Illinois, Urbana
Physical Description
paper (overall material)
overall:.1 cm x 12.4 cm x 3.5 cm; 1/32 in x 4 7/8 in x 1 3/8 in
ID Number
accession number
catalog number
Credit Line
Gift of Prof. Wolfgang Haken
See more items in
Medicine and Science: Mathematics
Data Source
National Museum of American History
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