Sudoku puzzles and how to solve them

The Sudoku, a Latin square completion puzzle, has already conquered The Netherlands some time ago, surpassing in popularity the so-called griddlers (‘Japanse puzzels’ in Dutch). The puzzle was invented in Indianapolis in 1979 by Howard Garns. Garns contributed his puzzles to Dell Magazines, under the name of ‘Number Place’. Interest in Sudoku surged due to a revival in Japan in 1986, when puzzle publisher Nikoli rediscovered the game. The name ‘Sudoku’ is the Japanese abbreviation of a longer phrase, "Suuji wa dokushin ni kagiru", meaning ‘the digits must remain single’ (source: Wikipedia). Although solving the puzzle is a trivial task for a computer, the puzzle has many interesting mathematical properties. There are even some open problems attached to it, as Andries Brouwer, professor in graph theory at the Technische Universiteit Eindhoven, shows in this article.