It was first proposed by Francis Guthrie in 1852, and incorrectly proved by Alfred Kempe in 1879, who erroneously asserted that any normal map contained some region with fewer than six adjacent regions.  
It was first proposed by Francis Guthrie in 1852, and incorrectly proved by Alfred Kempe in 1879, who erroneously asserted that any normal map contained some region with fewer than six adjacent regions.  The correct 1979 proof uses Heesch's discharching method to find an unavoidable set of reducible configura-tions, which had to be analyzed using a computer program. The Heawood conjecture informed its proof by giving an upper bound for, which was wrong for the Klein bottle. FTP, what theorem proved by Wolfgang Haken and Kenneth Appel says that all maps of contiguous regions are colorable by certain number of colors?
It was first proposed by Francis Guthrie in 1852, and incorrectly proved by Alfred Kempe in 1879, who erroneously asserted that any normal map contained some region with fewer than six adjacent regions.  
Four-Color Theorem