FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in          Games  Calendar Log in to check your private messages    Some questions about ALS-xz          Sudoku Programmers Forum Index -> Programming sudoku View previous topic :: View next topic   Author Message Lunatic Joined: 11 Mar 2007 Posts: 166 : Location: Ghent - Belgium Items Posted: Tue Jun 10, 2008 10:29 am    Post subject: Some questions about ALS-xz I want to take my solver to the next level, implementing a lookup routine for ALS-xz. At first I was thinking to collect all possible ALSs on the grid, and then to handle all possible pairs of ALSs looking for possible common restricted candidates, and if found one then looking for a non restricted common candidate that could lead to eliminations. Sounds good in theory, but i think i will end up with a huge amount of ALSs to collect and compare, mostly leading to nothing and wasting time. So, i need a different approach. I searched the "programming sudoku" forum but to no avail. Thinking it over, i came to the conclusion to look for possible restricted common candidates first, and then lookup if i could place them in ALSs, and if so, look for a non-restricted common candidate that leads to eliminations. How about this ? If anyone knows a better approach, please let me know... Tnx, Marc. _________________ Marc ~~~<><~~~<><~~~<><~~~<><~~~ Last edited by Lunatic on Tue Jun 24, 2008 5:05 pm; edited 2 times in total Back to top hobiwan Joined: 11 Feb 2008 Posts: 83 : Items Posted: Tue Jun 10, 2008 5:30 pm    Post subject: I went with your first approach (collect all ALS, all RCs then search for possible eliminations), mostly because I was too lazy to think about something better. I can live with the results. To give you a ballpark figure: Typical grids I tested had between 150 an 250 ALS with a total of about 1000 RCs (up to 2000 in rare cases). It is probably possible to reduce the number of ALS by excluding ALS that contain naked pairs (I have not done that yet). Back to top Lunatic Joined: 11 Mar 2007 Posts: 166 : Location: Ghent - Belgium Items Posted: Tue Jun 10, 2008 6:03 pm    Post subject: hobiwan wrote: It is probably possible to reduce the number of ALS by excluding ALS that contain naked pairs (I have not done that yet). Well, that is surely something to keep in mind when i begin to write the ALS-xz code. Just a few quick thoughts... - Could it be that any naked subset in its whole is not useful as part of an ALS ? - I think that mixing parts of two naked subsets together for making a single ALS is not very useful either. Which would mean that any useable ALS is a subset from a naked subset (or from the whole set if no subsets are present) Can anyone confirm this ? _________________ Marc ~~~<><~~~<><~~~<><~~~<><~~~ Back to top Lunatic Joined: 11 Mar 2007 Posts: 166 : Location: Ghent - Belgium Items Posted: Sat Sep 13, 2008 12:19 pm    Post subject: I wrote: Can anyone confirm this ? I've asked this same question at the players forum a while ago where these thoughts are confirmed by ronk. _________________ Marc ~~~<><~~~<><~~~<><~~~<><~~~ Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         Sudoku Programmers Forum Index -> Programming 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