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Re: Euro's and Dollars.

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Andrew Haley <andrew29@littlepinkcloud.invalid> writes:
>Anton Ertl <anton@mips.complang.tuwien.ac.at> wrote:
>> Albert van der Horst <albert@spenarnc.xs4all.nl> writes:
>>>In article <2012Jun20.124603@mips.complang.tuwien.ac.at>,
>>>Anton Ertl <anton@mips.complang.tuwien.ac.at> wrote:
>>>>Albert van der Horst <albert@spenarnc.xs4all.nl> writes:
>>>>>(Officially a sudoku must not require backtracking to solve it.)
>>>>
>>>>But what does that mean?
...
>It means that at every stage in a solution you can iterate around all
>the empty squares and find at least one square that has only one
>possible value, given the values already known.  You don't at any
>point need to speculate about the value of a square and then make
>trial solutions.

Two people have misunderstood me.  I must be very unclear.  I'll try
to be clearer:

We have players Alice and Bob who have different Sudoku-solving
capabilities, for whatever reason.  So there will be a Sudoku where
Alice can deduce via a complex reasoning that a square has only one
possible value.  Bob does not use this reasoning and is not able to
deduce this, and can solve this Sudoku only with backtracking.

Does this Sudoku satisfy the non-backtracking rule?  Is there a limit
to what reasonings the players are required to apply before they can
claim that the Sudoku requires backtracking?

- anton
-- 
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
     New standard: http://www.forth200x.org/forth200x.html
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Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-18 19:00 +0000
  Re: Euro's and Dollars. "A. K." <akk@nospam.org> - 2012-06-18 23:18 +0200
    Re: Euro's and Dollars. Mark Wills <markrobertwills@yahoo.co.uk> - 2012-06-19 00:20 -0700
      Re: Euro's and Dollars. "Elizabeth D. Rather" <erather@forth.com> - 2012-06-18 21:51 -1000
  Re: Euro's and Dollars. vandys@vsta.org - 2012-06-19 00:49 +0000
    Re: Euro's and Dollars. Spam@ControlQ.com - 2012-06-18 21:43 -0400
      Re: Euro's and Dollars. "A. K." <akk@nospam.org> - 2012-06-19 07:20 +0200
        Re: Euro's and Dollars. Ecki <ecki@intershop.de> - 2012-06-19 09:26 +0200
          Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-19 15:58 +0000
            Re: Euro's and Dollars. "A. K." <akk@nospam.org> - 2012-06-19 19:58 +0200
              Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-20 01:31 +0000
                Re: Euro's and Dollars. "A. K." <akk@nospam.org> - 2012-06-20 07:15 +0200
            Re: Euro's and Dollars. Ecki <ecki@intershop.de> - 2012-06-20 10:15 +0200
            Re: Euro's and Dollars. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-20 10:46 +0000
              Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-20 17:39 +0000
                Re: Euro's and Dollars. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-21 16:21 +0000
                Re: Euro's and Dollars. Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-21 11:58 -0500
                Re: Euro's and Dollars. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-22 14:57 +0000
                Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-21 20:38 +0000
      Re: Euro's and Dollars. vandys@vsta.org - 2012-06-19 15:49 +0000
    Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-19 15:43 +0000
      Re: Euro's and Dollars. vandys@vsta.org - 2012-06-19 15:51 +0000
  Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-19 15:41 +0000
    Re: Euro's and Dollars. Paul Rubin <no.email@nospam.invalid> - 2012-06-19 10:26 -0700
      Re: Euro's and Dollars. Paul Rubin <no.email@nospam.invalid> - 2012-06-19 23:34 -0700
    Re: Euro's and Dollars. Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-19 12:41 -0500
      Re: Euro's and Dollars. Paul Rubin <no.email@nospam.invalid> - 2012-06-19 11:10 -0700
        Re: Euro's and Dollars. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-20 03:12 +0000
          Re: Euro's and Dollars. Paul Rubin <no.email@nospam.invalid> - 2012-06-19 23:51 -0700
        Re: Euro's and Dollars. Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-20 03:15 -0500

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