Graphs and NetworksMaps

We have already used graph theory with certain maps. As we zoom out, individual roads and bridges disappear and instead we see the outline of entire countries.

When colouring a map – or any other drawing consisting of distinct regions – adjacent countries cannot have the same colour. We might also want to use as few different colours as possible.

Some simple “maps”, like a chessboard, only need two colours (black and white), but most complex maps need more.