FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in          Games  Calendar Log in to check your private messages    Need help on this puzzle          Sudoku Programmers Forum Index -> Solving sudoku View previous topic :: View next topic   Author Message gary Joined: 10 Feb 2007 Posts: 1 : Location: San Diego Items Posted: Sat Feb 10, 2007 8:42 pm    Post subject: Need help on this puzzle *------------------------------------* | 4 8 7 | 3 1 9 | 2 6 5 | | 1 6 5 | 4 8 2 | 9 3 7 | | 3 2 9 | 6 57 57 | 4 8 1 | |-------------------------------------- | | 9 3 2 | 7 4 15 | 6 15 8 | | 6 5 1 | 2 3 8 | 7 9 4 | | 8 7 4 | 19 59 6 | 15 2 3 | |---------------------------------------| | 57 4 6 | 19 79 3 | 8 157 2 | | 2 1 8 | 5 6 47 | 3 47 9 | | 57 9 3 | 8 2 147 | 15 1457 6| *---------------------------------------* Thanks for the help on this. Gary Back to top daj95376 Joined: 05 Feb 2006 Posts: 349 : Items Posted: Sat Feb 10, 2007 11:31 pm    Post subject: Your grid might be solvable by a BUG+3, but I don't know for sure. There also appears to be a Unique Rectangle possibility on <57> in [r79c18], but I didn't pursue it. What I did find was a simple Coloring elimination that leads to the puzzle being solved with Singles. If you look at the B(lue)/G(reen) coloring on <1> below, you'll see a pattern that's called a Two-String Kite (I believe). Anyway, it leads to [r7c8]<>1 and cracks your puzzle. Code: *-----------------------------------------------------------* | 4     8     7     | 3     1     9     | 2     6     5     | | 1     6     5     | 4     8     2     | 9     3     7     | | 3     2     9     | 6     57    57    | 4     8     1     | |-------------------+-------------------+-------------------| | 9     3     2     | 7     4    G15    | 6    B15    8     | | 6     5     1     | 2     3     8     | 7     9     4     | | 8     7     4     |B19    59    6     | 15    2     3     | |-------------------+-------------------+-------------------| | 57    4     6     |G19    79    3     | 8     57-1  2     | | 2     1     8     | 5     6     47    | 3     47    9     | | 57    9     3     | 8     2     147   | 15    1457  6     | *-----------------------------------------------------------* Back to top Carcul Joined: 29 Dec 2005 Posts: 50 : Location: Coimbra, Portugal Items Posted: Thu Feb 15, 2007 3:49 pm    Post subject: Another Solution R9c8 must be "1", otherwise we would have a TILA(1) in cells {r9c7|r6c7|r4c8|r4c6|r9c6}. That solves the puzzle. Carcul Back to top rkral Joined: 21 Oct 2005 Posts: 233 : Items Posted: Thu Feb 15, 2007 6:42 pm    Post subject: Re: Another Solution Carcul wrote: R9c8 must be "1", otherwise we would have a TILA(1) in cells {r9c7|r6c7|r4c8|r4c6|r9c6}. That solves the puzzle. Carcul I found no description here for TILA. What is it? Back to top Pat Joined: 06 Sep 2006 Posts: 128 : Items Posted: Fri Feb 16, 2007 8:28 am    Post subject: re: TILA rkral wrote: I found no description here for TILA. What is it? how about this -- Two Incompatible Nice Loops Two Incompatible Loop Analysis (TILA) Almost Nice Loops Back to top Carcul Joined: 29 Dec 2005 Posts: 50 : Location: Coimbra, Portugal Items Posted: Fri Feb 16, 2007 11:01 am    Post subject: TILA = Two Incompatible Loops Argument. See the link Pat has given. Back to top rkral Joined: 21 Oct 2005 Posts: 233 : Items Posted: Fri Feb 16, 2007 12:18 pm    Post subject: Re: re: TILA daj95376 wrote: Code: *-----------------------------------------------------------* | 4     8     7     | 3     1     9     | 2     6     5     | | 1     6     5     | 4     8     2     | 9     3     7     | | 3     2     9     | 6     57    57    | 4     8     1     | |-------------------+-------------------+-------------------| | 9     3     2     | 7     4    G15    | 6    B15    8     | | 6     5     1     | 2     3     8     | 7     9     4     | | 8     7     4     |B19    59    6     | 15    2     3     | |-------------------+-------------------+-------------------| | 57    4     6     |G19    79    3     | 8     57-1  2     | | 2     1     8     | 5     6     47    | 3     47    9     | | 57    9     3     | 8     2     147   | 15    1457  6     | *-----------------------------------------------------------* Carcul wrote: R9c8 must be "1", otherwise we would have a TILA(1) in cells {r9c7|r6c7|r4c8|r4c6|r9c6}. That solves the puzzle. (...) TILA = Two Incompatible Loops Argument. See the link Pat has given. Pat wrote: Almost Nice Loops Based on the cells you gave (r9c7|r6c7|r4c8|r4c6|r9c6), I see one loop r9c6=1 => r4c6<1> r4c8=1 => r6c7<1> r9c7=1 => r9c6<>1 so r9c6 cannot be digit 1 What is the 2nd? For that matter, why is a 2nd even required? Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         Sudoku Programmers Forum Index -> Solving sudoku All times are GMT Page 1 of 1   Jump to: Select a forum Sudoku----------------Solving sudokuSetting sudokuProgramming sudokuThe mathematics of sudokuExotic sudoku Library----------------PuzzlesSoftwareSudoku elsewhere Not sudoku----------------Random thoughtsForum feedback  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum   Powered by phpBB © 2001, 2005 phpBB Group Igloo Theme Version 1.0 :: Created By: Andrew Charron