http://idle.slashdot.org/story/12/01/08/1845258/lower-limit-found-for-sudoku... Posted by <http://www.monkey.org/%7Etimothy/>timothy on Sunday January 08, @10:46AM from the 17-ain't-young dept. ananyo writes "An Irish mathematician has used a complex algorithm and millions of hours of supercomputing time to solve an important open problem in the mathematics of Sudoku, the game popularized in Japan that involves filling in a 9X9 grid of squares with the numbers 19 according to certain rules. Gary McGuire of University College Dublin shows in a <http://www.math.ie/McGuire_V1.pdf>proof posted online [PDF] that the minimum number of clues or starting digits needed to complete a puzzle is 17; <http://www.nature.com/news/mathematician-claims-breakthrough-in-sudoku-puzzle-1.9751>puzzles with 16 or fewer clues do not have a unique solution. Most newspaper puzzles have around 25 clues, with the difficulty of the puzzle decreasing as more clues are given." --- co-chair http://ocjug.org/