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dagoldlin Guest

Posted: Thu Oct 27, 2005 5:57 pm Post subject: what governs difficulty? 


I am new to Sudoku and note that the puzzles are graded. On what factors is this grading based? (I can see that number of filledin squares would be one.)
I like puzzles that can be solved by logic alone. Is it possible in Sudoku to have to try one of two choices, go through a number of steps only to get blocked, then have to go back to the other choice? Thanks for your help. 

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David Bryant
Joined: 29 Jul 2005 Posts: 559 Location: Denver, Colorado

Posted: Thu Oct 27, 2005 7:08 pm Post subject: Re: what governs difficulty? 


dagoldlin wrote:  I am new to Sudoku and note that the puzzles are graded. On what factors is this grading based? (I can see that number of filledin squares would be one.) 
Samgj says his method of grading the puzzles is subjective. There's currently a rather lengthy discussion of grading going on in this forum, right here.
dagoldlin wrote:  I like puzzles that can be solved by logic alone. Is it possible in Sudoku to have to try one of two choices, go through a number of steps only to get blocked, then have to go back to the other choice? Thanks for your help. 
It's not only possible, it's actually rather common. You might want to read "The logic argument," also in this forum. Oh  Samgj, the webmaster here, claims that one never has to guess when solving his puzzles. That's one of the main attractions of The Daily Sudoku, imho.
Part of the skill in Sudoku involves being able to see ahead for a few moves. So what appears to be a "trial and error" technique to a newbie may look like a straightforward logical move to a player with more experience. You may want to read the description of "block on block interactions" to understand this a bit better.
Happy Sudokuing! dcb 

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dagoldlin Guest

Posted: Fri Oct 28, 2005 10:53 pm Post subject: thanks! 


That was most helpful. I'll check out the other threads. Thanks so much! 

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chelsea
Joined: 29 Oct 2005 Posts: 2

Posted: Sat Oct 29, 2005 4:02 am Post subject: 


I've found that going to the leastlikely 'empty space' will yield the best results  I logically think that the center squares will be the place to fill in blanks. But  putting my pen over a #7 square in the top right might give me more info, such as, that square HAS TO be either 4 or 7. Ergo, the one below that HAS TO be either 6 or 9 is eliminated in a vertical scan of the available numbers.
I adore Sudoko for the same reason that I adore Cross Sums  I've been told I'm a math idiot for most of my life, but I KNOW how Cross Sums work, and it makes logical sense to my Englishtrained brain. Just as word progressions 'make sense' in English, so does the fact that a threeblock "23" in Cross Sums MUST contain 6/8/9. A twoblock "3" must contain 1/2; a twoblock "4" must contain 1/3, ergo when a 3 and a 4 cross  the "1" must go in the block where they meet.
I use that same logic to solve Sudoku.
GAMES magazine has published them for years under a different name, but nobody paid much attention.
I now have coworkers sidling up to me saying, "I hear YOU know how to Sudoku, can you help me with..."
It's great. 

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alanr555
Joined: 01 Aug 2005 Posts: 193 Location: Bideford Devon EX39

Posted: Tue Nov 01, 2005 1:10 am Post subject: Re: what governs difficulty? 


Code: 
> Part of the skill in Sudoku involves being able to see ahead for a few
> moves.
So that is why I have so much difficulty!!
I take every move as it comes and do not look ahead at all  certainly
not in the sense that one needs to look ahead in chess.
I believe that the lookahead is necessary in order to reduce solvetime
(by knowing which part of the puzlle to tackle next) but it should not
be a factor in being able to solve most puzzles.
The whole concept of 'knowing what to do next' eludes me.
How do others decide what to do next?
Alan Rayner BS23 2QT



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someone_somewhere
Joined: 07 Aug 2005 Posts: 275 Location: Munich

Posted: Tue Nov 01, 2005 7:32 am Post subject: 


Hi,
Quote:  The whole concept of 'knowing what to do next' eludes me.
How do others decide what to do next?

That's the most hidden secret of humanity. You have to look deep into the genetic code and I am not sure if this is enough.
You can take a shortcut:
"Do, what you have to do; it's not so important what you do, but how you do it".
Just supply us with some Sudoku positions, you have trouble with, and I can try to apply this Zen theory to it 

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