Why is it enough to use 4 colors for painting a map in order that no two countries with the same color have a common border?
This can be easily found in any book which deals with design and analysis of algorithms .Refer to the topic "map colouring problem". One of the best books is the one by Cormen/Lieserson/Rivest
Many countries have traditions of painting, coloring or otherwise decorating eggs for Easter. This was a common pagan spring tradition, and has been incorporated into the christian traditions of many countries. Additionally, many non-christian countries have begun practicing the pagan trappings of christian Easter traditions. Chocolate eggs and bunnies can be seen in many countries where Christianity is not practiced widely. Simple dyed eggs at Easter are common throughout Europe, North America, and Australia. Intricately…
they are both western European countries, both democraties, both using a language based mostly on Latin, both having Roman Catholicism as the mainstream religion. They are the two largest countries within the European Union. They are both members of the Eurozone. They share a common border (the Pyrénées mountain range). A border, the currency. They're both European countries.