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                | |  |  | ChPicard 
 
 |  | Joined: 12 Mar 2008 |  | Posts: 82 |  | : |  | Location: Montreal, Canada |  | Items
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                                |  Posted: Mon Nov 02, 2009 7:15 am    Post subject: Conditions for a valid 17 given sudoku |   |  
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                                | 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
 
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 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 |  | : |  |  |  | Items
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                                |  Posted: Tue Nov 03, 2009 8:16 pm    Post subject: |   |  
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                                | 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.
 
 I perhaps could confirm this one 	  | Code: |  	  | +---+---+---+ |1..|...|...|
 |...|1..|...|
 |...|...|1..|
 +---+---+---+
 |...|...|...|
 |...|...|...|
 |...|...|...|
 +---+---+---+
 |...|...|...|
 |...|...|...|
 |...|...|...|
 +---+---+---+
 | 
 
 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 |  | : |  |  |  | Items
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                                |  Posted: Thu Nov 05, 2009 1:43 am    Post subject: |   |  
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                                | 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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