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Topic: sudoku, again
Replies: 34   Last Post: Sep 24, 2011 8:41 PM

 Messages: [ Previous | Next ]
 Stephen J. Herschkorn Posts: 2,297 Registered: 1/29/05
Re: sudoku, again
Posted: Sep 17, 2011 4:36 PM
 att1.html (1.9 K)

Mike Terry wrote:

>"Rock Brentwood" <federation2005@netzero.com> wrote in message
>[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

Date Subject Author
9/15/11 Rich Delaney
9/15/11 Brian Q. Hutchings
9/15/11 Eric Sosman
9/16/11 Rock Brentwood
9/17/11 Mike Terry
9/17/11 Mike Terry
9/17/11 Eric Sosman
9/17/11 Mike Terry
9/21/11 Moshe Rubin
9/21/11 Willem-Jan Monsuwe
9/21/11 Moshe Rubin
9/21/11 Mike Terry
9/22/11 Moshe Rubin
9/22/11 Mike Terry
9/22/11 Rock Brentwood
9/17/11 Stephen J. Herschkorn
9/18/11 Herman Rubin
9/19/11 Rich Delaney
9/19/11 Tommy Jensen
9/20/11 Willem-Jan Monsuwe
9/20/11 Brian Q. Hutchings
9/21/11 Tommy Jensen
9/21/11 Rich Delaney
9/21/11 bulland@gmail.com
9/22/11 Stephen J. Herschkorn
9/22/11 Brian Q. Hutchings
9/22/11 Brian Q. Hutchings
9/22/11 Willem-Jan Monsuwe
9/23/11 Rich Delaney
9/23/11 quasi
9/24/11 Matthew Russotto
9/24/11 Matthew Russotto
9/22/11 Rock Brentwood
9/22/11 Rock Brentwood