A solved puzzle

This one is solvable, because there are 17 clues

If you pick up a Sudoku puzzle with your morning coffee, you may want to count the number of clues before you begin. An Irish mathematician has recently proven that Sudoku puzzles with 16 clues or less do not have unique solutions. Sudoku fans and mathematicians have long suspected that designing a puzzle with 16 clues was impossible. Using a supercomputing facility, Gary McGuire was able to prove it. Unfortunately, if you’re struggling with a more forgiving puzzle, you have no one to blame but yourself.

Further reading:
Pre-print of the paper: arXiv:1201.0749v1
Nature news coverage

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