SSC 01 ♬ Bótané, Myrosa ♬ Grand Final

The map made me think about an interesting mathematical result: anybody can understand it but the proof was very tricky to obtain - and without the help of computers it would probably be still a conjecture today (a result that is supposed to be true but with no proof).

Take a map (real or imaginary) and divide it into regions, countries or what you want. You decide to associate each region with a colour, which must be different from any neighbour region (for example, if a region is red on the map, the other regions that share a border with it can be green, blue, yellow or whatever but not red).

The theorem says that you need only four different colours for the entire map, whatever the configuration of the regions/countries is. Of course, you can use more colours but you can find a solution with only four colours. This theorem is called the Four Colour Theorem.

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