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Mathematician Claims Breakthrough in Sudoku Puzzle
from Nature News
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 1-9 according to certain rules.
Gary McGuire of University College Dublin shows in a proof posted online on 1 January that the minimum number of clues--or starting digits--needed to complete a puzzle is 17; 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.
The emerging consensus among mathematicians at a conference in Boston, Massachusetts, on 7 January was that McGuire's proof is probably valid and an important advance in the growing field of Sudoku maths.