17 and Sudoku Clues
17 is the minimum number of clues required to give a unique sudoku solution - but how did mathematicians prove this?
Featuring James Grime.
Dr James Grime discusses a recent paper which cracked the problem. The paper being discussed by McGuire and others is at http://arxiv.org/abs/1201.0749
James Grime's website is at http://singingbanana.com/