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what is the minimum number of hints must be provide in a Sudoku with only one solution in order to reach the answer?

Also if you are interested, please provide a reference.

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If by "hints" you mean the number of filled cells of a standard 9x9 grid, there are examples (with unique solution) having 17 "hints". No examples with fewer filled cells are known, but it's conjectured that this is the minimum required for a unique solution. – hardmath Dec 30 '13 at 22:19
Note that typing the text of your question: "what is the minimum number of hints must be provide in a Sudoku" into Google would have given you all that is in my answer... – Thomas Andrews Dec 30 '13 at 22:55
@ThomasAndrews Typing it into Math Stack Exchange also works. – bof Dec 30 '13 at 23:23
@ThomasAndrews I was going to say that typing the question into Google might not give Victor all the comments your answer is going to get. But I would have been wrong: the first Google hit is this page at MSE. – bof Dec 30 '13 at 23:36
up vote 5 down vote accepted

According this this link, $17$ is the smallest number of hints.

The paper is at .

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Some commentary on the paper is given here, on a website devoted to constructing sudoku solvers and related software. – hardmath Dec 30 '13 at 22:30

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