Solving sudoku puzzles may not require mathematics, but mathematicians have found plenty to say about the popular brainteasers.

This paper presents a non-technical exposition of graph theory (more particularly, the theory of directed graphs or digraphs), followed by a survey of the literature on applications of graph theory in ...

In theory, it cannot be ruled out that the algorithms might run for longer than the age of the universe. But in practice, many algorithms seem to work just fine.