FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in          Games  Calendar Log in to check your private messages    Problem with logic          Sudoku Programmers Forum Index -> The mathematics of sudoku View previous topic :: View next topic   Author Message g_hickley Joined: 02 Dec 2005 Posts: 3 : Items Posted: Wed Jan 11, 2006 10:30 am    Post subject: Problem with logic I had a Sudoku game developed for my website by a third-party. A few users have described an issue where two numbers are inter-changeable creating more than one solution for the same puzzle. Below is an example - both highlighted 4 and 7 are inter-changeable. Could someone describe what problem? _________________ Toba Data Recovery Back to top Moschopulus Joined: 12 Aug 2005 Posts: 39 : Items Posted: Wed Jan 11, 2006 11:04 am    Post subject: You must have one of these four numbers as a given clue in the puzzle. Otherwise, as you say, the puzzle has two solutions. The same is true for any set like this. Sudoku has one solution by definition, so a puzzle with more than one solution is not a proper sudoku puzzle. Back to top g_hickley Joined: 02 Dec 2005 Posts: 3 : Items Posted: Wed Jan 11, 2006 11:30 am    Post subject: Moschopulus wrote: You must have one of these four numbers as a given clue in the puzzle. Otherwise, as you say, the puzzle has two solutions. The same is true for any set like this. Sudoku has one solution by definition, so a puzzle with more than one solution is not a proper sudoku puzzle. Thanks for your reply. The difficulty is being able to recognise this in the algorithm and to fill in one of the four. _________________ Toba Data Recovery Back to top Ruud Site Admin Joined: 17 Sep 2005 Posts: 708 : Location: Netherlands Items Posted: Wed Jan 11, 2006 12:34 pm    Post subject: Hi, when you search this forum using the search terms: "unavoidable sets" you'll find a lot more information on this topic. There are more complex patterns than just the 4-cell rectangle. Ruud. _________________ Meet me at sudocue.net Back to top g_hickley Joined: 02 Dec 2005 Posts: 3 : Items Posted: Sun Jan 15, 2006 10:08 am    Post subject: Another one Back to top Ruud Site Admin Joined: 17 Sep 2005 Posts: 708 : Location: Netherlands Items Posted: Sun Jan 15, 2006 3:14 pm    Post subject: It is worse than you think.... Ruud. _________________ Meet me at sudocue.net Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         Sudoku Programmers Forum Index -> The mathematics of 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