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Re: sudoku, again
Posted:
Sep 17, 2011 4:36 PM
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Mike Terry wrote:
>"Rock Brentwood" <federation2005@netzero.com> wrote in message
>news:6c619e53-d125-494f-a3fb-13850c9a0aab@19g2000vbx.googlegroups.com...
>[snip..]
>
>
>>The REAL issue is that to solve a Sudoku grid, there are actually TWO
>>parts: (a) find a solution (i.e. prove that one exists), but also (b)
>>prove that it is the ONLY solution.
>>
>>
>
>I've never come across a sudoku variant where part of the objective was to
>prove the solution is unique. In contrast, many sudoku puzzles actually
>state up front that the solutions are unique as one of the puzzle
>constraints, and the ones that don't do this *are* in fact always unique,
>i.e. they have just made the constraint a "secret rule" of the puzzle
>(grrrr!).
>
It's no secret. But if there is not a unique solution, the solver by
necessity gets to a point where the "next step" is no longer logically
implied by the structure of the puzzle. That is, you have several
equally valid guesses, all of which lead to a solution. That defeats
the whole purpose of the puzzle.
--
Stephen J. Herschkorn sjherschko@netscape.net
Math Tutor on the Internet and in Central New Jersey and Manhattan
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