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Conditions for a valid 17 given sudoku

 
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ChPicard

Joined: 12 Mar 2008
Posts: 82
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Location: Montreal, Canada

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PostPosted: Mon Nov 02, 2009 7:15 am    Post subject: Conditions for a valid 17 given sudoku Reply with quote

Conditions for a valid 17 given sudoku
coloin wrote:

But many of these will be invalid.
eg
must have at least 1 clue in every double row of 18 clues
must have at least 3 clues in a band of 27 clues ?
must have at least 8 clues in 2 bands [2 x 27 clues]
must have no more than 9 clues in a band


must have 0 or 1 number missing



Never seen in Royle's database (49151 different puzzles):

5 times (or more) the same number
3 empty boxes
5 givens in the same row, column
6 givens in the same box
2 (or less), 10 (or more) givens in the same band or stack

Could you confirm and complete?

Thank you

JPS
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coloin

Joined: 05 May 2005
Posts: 97
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PostPosted: Tue Nov 03, 2009 8:16 pm    Post subject: Reply with quote

Well - even too much for my programmining skills !

gsf's program can count the clue freq and clues in a box - that could be done easily. The other conditions im sure gsf could confirm.

Does it help us do a {-3+3} ? it might but it would be darn complex.

I also havnt seen a 17-puzzle which had these [equivalent] clues.
Code:
+---+---+---+
|1..|...|...|
|...|1..|...|
|...|...|1..|
+---+---+---+
|...|...|...|
|...|...|...|
|...|...|...|
+---+---+---+
|...|...|...|
|...|...|...|
|...|...|...|
+---+---+---+
I perhaps could confirm this one

I also havnt seen a 17-puzzle which didnt have these [equivalent] clues.
Code:
+---+---+---+
|1..|...|...|
|...|2..|...|
|...|...|...|
+---+---+---+
|.3.|...|...|
|...|.4.|...|
|...|...|...|
+---+---+---+
|...|...|...|
|...|...|...|
|...|...|..5|
+---+---+---+

There are puzzles with,6,7 and 8 clues.

There are only 2 of the 17-puzzles have the 9-clue arranged as such
Code:
+---+---+---+
|1..|...|...|
|...|2..|...|
|...|...|3..|
+---+---+---+
|.4.|...|...|
|...|.5.|...|
|...|...|.6.|
+---+---+---+
|..7|...|...|
|...|..8|...|
|...|...|..9|
+---+---+---+

But this doesnt really help us do a {-3+3} either.

C
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daj95376

Joined: 05 Feb 2006
Posts: 349
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PostPosted: Thu Nov 05, 2009 1:43 am    Post subject: Reply with quote

Useless Tidbit #1

Of the 48826 17's that I downloaded and converted to MinLex format, all contain coloin's pattern:

Code:
 +-----------------------+
 | 1 2 3 | 4 5 6 | 7 8 9 |
 | 4 5 . | . 8 9 | . . . |
 | . . . | . . . | . . . |
 |-------+-------+-------|
 | 2 . . | . . . | . . . |
 | . . . | . . . | . . . |
 | . . . | . . . | . . . |
 |-------+-------+-------|
 | . . . | . . . | . . . |
 | . . . | . . . | . . . |
 | . . . | . . . | . . . |
 +-----------------------+


Maybe someone will eventually find a "17" whose MinLex format matches:

Code:
 +-----------------------+
 | 1 2 3 | 4 5 6 | 7 8 9 |
 | 4 5 . | 8 9 . | . . . |
 | . . . | . . . | . . . |
 |-------+-------+-------|
 | 2 . . | . . . | . . . |
 | . . . | . . . | . . . |
 | . . . | . . . | . . . |
 |-------+-------+-------|
 | . . . | . . . | . . . |
 | . . . | . . . | . . . |
 | . . . | . . . | . . . |
 +-----------------------+

Useless Tidbit #2

There were 2853 duplicates after converting to MinLex format.
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