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Topic: Sudoku
Replies: 51   Last Post: Sep 26, 2005 3:12 AM

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Arthur J. O'Dwyer

Posts: 91
Registered: 12/13/04
Re: Sudoku
Posted: Aug 25, 2005 4:07 PM
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On Thu, 25 Aug 2005, Simon Tatham wrote:
[...]
> Hmm. I suppose it could be seen that way, although that's not how I
> saw it. I saw it as a special case of a rather different pattern,
> which I currently describe as `mutual neighbour analysis'. Rather
> than being a chain of arbitrary length, this pattern involves
> finding two non-adjacent squares and a bunch of their mutual
> neighbours, and observing that placing a particular number in one of
> the end squares forces all the neighbours to take values which cause
> a contradiction in the other end square.

[...]
> If the 45 square has a 4 in it, [...] a problem. Hence, the 45 square
> can't be a 4, so must be a 5.


Tell me again how this is distinct from "backtracking"? Basically,
your method is

1. Fill in a value for cell X.
2. Fill in a value for cells Y, Z,... dependent on X.
3. If at any point you find a contradiction, return to step 1.

That looks a lot like backtracking to me!

(Not that backtracking is bad; I just don't see why this particular
class of backtracking applications is interesting.)

-Arthur,
Sudoku is crosswording for the illiterate


Date Subject Author
8/15/05
Read Sudoku
Ioannis
8/15/05
Read Re: Sudoku
Stephen J. Herschkorn
8/15/05
Read Re: Sudoku
Stephen J. Herschkorn
8/15/05
Read Re: Sudoku
Ioannis
8/15/05
Read Re: Sudoku (for Ioannis only)
Stephen J. Herschkorn
8/15/05
Read Re: Sudoku
Rainer Rosenthal
8/16/05
Read Re: Sudoku
Stephen J. Herschkorn
8/16/05
Read Re: Sudoku
Ioannis
8/17/05
Read Re: Sudoku
Axel Vogt
8/16/05
Read Re: Sudoku
Patrick Hamlyn
8/17/05
Read Re: Sudoku
Hauke Reddmann
8/17/05
Read Re: Sudoku
mareg@mimosa.csv.warwick.ac.uk
8/17/05
Read Re: Sudoku
John Ramsden
8/17/05
Read Re: Sudoku
mensanator
8/26/05
Read Group theory (permutations) and Rubik's cube (was: Re: Sudoku)
Jim Weisert
8/27/05
Read Re: Sudoku
Marc Olschok
8/24/05
Read Re: Sudoku
Simon Tatham
8/24/05
Read Re: Sudoku
puppet_sock@hotmail.com
8/24/05
Read Re: Sudoku
Simon Tatham
8/24/05
Read Re: Sudoku
Paul Nutteing
8/24/05
Read Re: Sudoku
Mark Thornquist
8/24/05
Read Re: Sudoku
r.e.s.
8/25/05
Read Re: Sudoku
Simon Tatham
8/25/05
Read Re: Sudoku
r.e.s.
8/25/05
Read Re: Sudoku
Simon Tatham
8/25/05
Read Re: Sudoku
r.e.s.
8/25/05
Read Re: Sudoku
Timothy Little
8/25/05
Read Re: Sudoku
Arthur J. O'Dwyer
8/25/05
Read Re: Sudoku
r.e.s.
8/25/05
Read Re: Sudoku
Timothy Little
8/26/05
Read Re: Sudoku
mareg@mimosa.csv.warwick.ac.uk
8/26/05
Read Re: Sudoku
Simon Tatham
8/24/05
Read Re: Sudoku
Patrick Hamlyn
8/25/05
Read Re: Sudoku
Ed Murphy
8/25/05
Read Re: Sudoku
Patrick Hamlyn
8/25/05
Read Re: Sudoku
Ed Murphy
8/25/05
Read Re: Sudoku
puppet_sock@hotmail.com
8/29/05
Read Re: Sudoku
edward@margaretcho.com
8/29/05
Read Re: Sudoku
r.e.s.
8/30/05
Read Re: Sudoku
Ulysse Keller
8/30/05
Read Re: Sudoku
r.e.s.
9/25/05
Read Re: Sudoku
jgnovak@superlink.net
9/26/05
Read Re: Sudoku
mensanator
9/26/05
Read Re: Sudoku
Jon Haugsand
9/26/05
Read Re: Sudoku
mensanator
9/26/05
Read Re: Sudoku
Stephen J. Herschkorn
8/17/05
Read Re: Sudoku
puppet_sock@hotmail.com
8/17/05
Read Re: Sudoku
Bob Jordan
8/15/05
Read Re: Sudoku
mensanator
8/26/05
Read Re: Sudoku
bill.daly@tradition-na.com
8/16/05
Read Re: Sudoku
Brian Quincy Hutchings
8/23/05
Read Re: Sudoku
SudokuJohn

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