Four Colours

Could be a map of USA or your country colored using four colors in such a way that Nebraska and Missouri (as well as any two contiguous regions or states) wouldn’t be filled with one color? It turns out that you can manage to do it with any map. And this seems to be the first statement in science proved with computer aid. You can verify this statement for variety of maps, study up geography and visit Martin Gardner country by the way.

Maps in this release:
• Commonwealth of Australia,
• Republic of Austria,
• French Republic,
• Federal Republic of Germany,
• United Mexican States,
• Republic of Poland,
• Portuguese Republic,
• Kingdom of Spain,
• Kingdom of Sweden,
• Swiss Confederation,
• United States of America,
• United Kingdom of Great Britain and Northern Ireland.