FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in          Games  Calendar Log in to check your private messages    asking for help          Sudoku Programmers Forum Index -> Solving sudoku View previous topic :: View next topic   Author Message Rachmaninov Joined: 18 Nov 2005 Posts: 5 : Items Posted: Fri Nov 18, 2005 6:12 pm    Post subject: asking for help I hope this is the right part of the forum for this question. Most sudoku's I can solve. But with the puzzle below, it seems that my knowledge of tactics is not enough to solve it. Sure I can solve it, by trying out some possibilities, but in my opninion this is NOT the right way to solve. Could anyone here, give me only ONE hint, only for the next possible move? With a logical explanation why this move is possible? Thanks very much in advance! Back to top Hakan Joined: 09 Oct 2005 Posts: 10 : Items Posted: Fri Nov 18, 2005 9:23 pm    Post subject: Re: asking for help Look at candidate 3s in row 7, 8 and 9. /Hakan Back to top Rachmaninov Joined: 18 Nov 2005 Posts: 5 : Items Posted: Fri Nov 18, 2005 9:34 pm    Post subject: Re: asking for help Hakan wrote: Look at candidate 3s in row 7, 8 and 9. /Hakan YES!!!! Wow! I think I am blind........... Thank you so very much!!! I really hope, I dont need a second hint......haha Back to top Hakan Joined: 09 Oct 2005 Posts: 10 : Items Posted: Fri Nov 18, 2005 10:00 pm    Post subject: Re: asking for help Rachmaninov wrote: I really hope, I dont need a second hint......haha I am sorry to say that I think that trial and error is required from this point. Tell me if I am wrong. How did the original clues look like? Are you sure you got them right? /Hakan Back to top Rachmaninov Joined: 18 Nov 2005 Posts: 5 : Items Posted: Fri Nov 18, 2005 10:18 pm    Post subject: Hakan, I think the hint you gave is NOT an error........with your hint I can exlude several other digits. But indeed, it does not lead to find a new number. So, only more digits to remove. It was really strange that I did not discover untill now the hint you gave me. In about 10 minutes I will give you the original puzzle again, and tell you too what I found so far............I will check again if the puzzle is okay, with my computer solver......thanks very much untill now for helping! Back to top Rachmaninov Joined: 18 Nov 2005 Posts: 5 : Items Posted: Fri Nov 18, 2005 10:36 pm    Post subject: Hi Hakan, here I am again I checked the puzzle with my computer solver, and the computer checked TOO if there were more than one solution. There is only one solution, found in < 1 sec. In this way I put it in my solver: 000070940 070090005 300005070 087400100 463000000 000007080 800700000 700000028 050268000 And here is a link to the puzzle itself...( at the website there you can enter your own puzzles) http://www.sokudo.be/sudoku/index.php?p=....7.94..7..9...53....5.7..874..1..463...........7.8.8..7.....7......28.5.268... Only things I can do now is: - remove the candidates 6 in A3 B3 and C3 - remove the candidates 1 in F4 and F5 - and then your hint!! remove the 3 in the fields G7 G8 G9 and H7 My way of notation is: A1 A2 A3 A4 A5 A6 A7 A8 A9 B1 B2 and so on C1 D1 E1 F1 G1 H1 I1 Hope you can do something with this information! Thanks again! Back to top rkral Joined: 21 Oct 2005 Posts: 233 : Items Posted: Sat Nov 19, 2005 12:50 pm    Post subject: Rachmaninov wrote: Only things I can do now is: - remove the candidates 6 in A3 B3 and C3 - remove the candidates 1 in F4 and F5 - and then your hint!! remove the 3 in the fields G7 G8 G9 and H7 I think the next step requires tabling, bifurcating implication chains, or some other advanced technique. My solver does forward implication chains and shows that if one assumes r5c5 (your E5) to be a 5 and follows the implications from there ... eventually r6c1 and r6c2 (your F1 and F2) would both be 2. Since two cells in a row cannot have the same value, the assumption is false and the 5 can be eliminated from r5c5. Few would reach that conclusion manually ... and there seem to be many more steps like that before a solution can be reached. Back to top Rachmaninov Joined: 18 Nov 2005 Posts: 5 : Items Posted: Sat Nov 19, 2005 4:59 pm    Post subject: rkal, thank you for your reply! 5 on E5 and the conclusion for F1 F2 seems to be right. I tried out.... and I think you are right too, that this puzzle needs much more advanced techniques. Do you share my opninion that this is a very exeptional puzzle? It's strange that these 4 puzzles on this forum, with only 17 startnumbers do NOT need these advanced techniques http://www.setbb.com/phpbb/viewtopic.php?t=129&mforum=sudoku number 1, 2 and 3 I can solve with my elementairy technique ( I am still busy with number 4) Perhaps I have to start with studying about "bifurcating implication chains" 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