How does the maker of a sudoku puzzle know that it does not have more than one solution?

September 16th, 2008


Some Sudoku puzzles DO have more than one answer. HOWEVER a well constructed sudoku puzzle has only one solution. In a book called How to solve Sudoku by Robin Wilson, it is stated that "The construction of a good sudoku puzzle is not an easy matter. The Nikoli Firm in Japan prides itself on the construction of interesting and ingenious sudoku patterns by HAND. On the other hand, the problem of constructing suitable patterns is a natural thing to program on a computer, and there are many such programs around the world that churn out sudoku patterns by the score (of varying complexity and quality).
Many websites contain information about Sudoku:
http://en.wikipedia.org/wiki/suduko
www.suduko.com
www.nikoli.co.jp/en

Posted in Sudoku Puzzle
5 Responses

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5 Responses to “How does the maker of a sudoku puzzle know that it does not have more than one solution?”

  1. Comment by yankeecrazy013
    April 17th, 2006

    they fill in all the boxes first and then delete a certain number of boxes
    References :

  2. Comment by bandf
    April 23rd, 2006

    A lot of times they will use a computer program to cross check their puzzle… in fact a lot of Sudoku puzzles are generated by computer.

    For puzzles generated by hand, the puzzle creator has to be sure to not create a case where they remove too many numbers and cause the solution to be non-unique.
    References :

  3. Comment by Desperately Seeking Paper
    April 28th, 2006

    Some Sudoku puzzles DO have more than one answer. HOWEVER a well constructed sudoku puzzle has only one solution. In a book called How to solve Sudoku by Robin Wilson, it is stated that "The construction of a good sudoku puzzle is not an easy matter. The Nikoli Firm in Japan prides itself on the construction of interesting and ingenious sudoku patterns by HAND. On the other hand, the problem of constructing suitable patterns is a natural thing to program on a computer, and there are many such programs around the world that churn out sudoku patterns by the score (of varying complexity and quality).
    Many websites contain information about Sudoku:
    http://en.wikipedia.org/wiki/suduko
    http://www.suduko.com
    http://www.nikoli.co.jp/en
    References :

  4. Comment by puppy_tiffie
    April 29th, 2006

    because they check it before they show anyone else and it's like not possible to have 2 answers in a sudoku puzzle.
    References :

  5. Comment by ash_minime
    April 29th, 2006

    they get a computer to do it
    References :