Some interesting X-sudokus

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Some interesting X-sudokus

Postby m_b_metcalf » Tue Mar 06, 2007 12:19 am

X-sudokus seem to have disapeared from view recently, but when I looked again at my program for this thread, I saw some interesting puzzles being produced during testing:
Code: Select all
 . . . 8 . 3 . . .
 . 3 . . . . . 7 .
 8 . . . . . . . 2
 . . . . 1 . . . .
 . . 5 4 . 6 3 . .
 . . . . 2 . . . .
 1 . . . . . . . 6
 . 9 . . . . . 2 .
 . . . 1 . 9 . . .  18-clue symmetric

Code: Select all
 . . . . . . . . .
 . . . . . . . . .
 4 . 5 3 . 1 9 . 8
 . 9 . 4 . 3 . 1 .
 1 . . . 2 . . . 3
 . 5 . 1 . 8 . 6 .
 3 . 8 9 . 7 6 . 1
 . . . . . . . . .
 . . . . . . . . .  2 x 2 empty rows, symmetric
 

Code: Select all
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . 6 . . . .
 . 1 . 4 . 8 . . 6
 9 . . 3 . . . . .
 . . . . 9 . 5 . .
 . 6 1 . . . . . 3
 . 4 . . . 2 . . 7   empty band, 15 clues

Is anyone still interested in these?

Regards,

Mike Metcalf
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Re: Some interesting X-sudokus

Postby udosuk » Tue Mar 06, 2007 8:01 am

m_b_metcalf wrote:Is anyone still interested in these?

In Ruud's website there're still daily X-file puzzles available.

In the holy land of Killer Sudoku, namely djape's website, about half of the puzzles available are X puzzles... And 80% of the puzzles posted in it's forum are with the X property... In fact it's becoming rarer and rarer to see non-X killer puzzles posted by the forum members there...

The X puzzles do have some attractiveness, and contain more fishy moves than non-X ones... I used to develop a bunch of turbot-fish style techniques and name them "crossover" moves...

I think the current record for fewest givens in an X puzzle is 13, perhaps you'd like to try your program's luck to break that record...:?:
udosuk
 
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Re: Some interesting X-sudokus

Postby m_b_metcalf » Tue Mar 06, 2007 2:17 pm

udosuk wrote:I think the current record for fewest givens in an X puzzle is 13, perhaps you'd like to try your program's luck to break that record...:?:


It's here. The problem is speed. It's well known that solvers slow down with fewer than about 20 clues. Working with fewer than 16 is far worse:( .

Regards,

Mike Metcalf
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