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Tough Sudoku for 12/May/2006

                 
                 
                 
                 
                 
                 
                 
                 
                 

Choose a number, and place it in the grid above.

  1 2 3 4 5 6 7 8 9
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Submitted by: Gath

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I can tell this isn't from around here!
Not too difficult.
Wow, was I first? Too much happening out in the world?
1st?
Is this not the Gate of Heavenly Peace in Beijing?
8:38 Maen
10.20 - with a couple of guesses
12:05
Set-up was so complicated (not as many cells solved as usual), that I decided to make one guess to get started. That was all it took -- everything fell into place after that.

I'd love to visit there!
Good Maen all! No time for me today...forgot to restart timer after a pause & I guessed a few times (too impatient today!)
Just had to make one (intelligent) guess; then the whole puzzle fell into place. Sweet! Good Maen to all!
i reckon this is the easiest 'tough' sudoku here ,,,,
Just in time, a puzzle with no backtracking for me. It does help to fill in the possibilities correctly. Maen to all. I wish everyone could see how spring green this part of the world is right now. I'm sure it would be a major advancement in the cause of world peace.
To the site maestros: For FC's, do you figure them out just by looking at them and seeing the logic or do you have to sort them out on some kind of draft? Are they pure logic or trial and error? Thanks for any answers.
13:08 - struggled in the beginning to remove numbers but then it all came to gether the last 4 minutes.
Me too, Jeana. Have a great one, all!
I also made one good guess and it fell into place quickly.Have a good mAen everyone.See you on the flip side.
Comment.
mAen to all. Brain dead on this one as it took forever. My reward? Another repeat picture!
10:52 good maEn all!
46:17
8:57
This one is a lot easier to solve than it is to prove. Here is a proof, although I hope that someone can come up with something simpler:

1) Start 22, UP to 26.
2) Hidden pair 59 at a1, c3 forbids a1=1278, c3=2.
3) f6=9 == d4=9 -- d4=5 == a4=5 -- a1=5 == a1=9 -- c3=9 == h3=9 -- h6=9 More...
15.06
Where is it? one guess needed.
28:14 messed up on the set up. :(
23:44 after setup.
Made an absolute mess!
Here is the approach I used for this not easy to prove puzzle.

1) Start at 22 filled - the given puzzle. Unique Possibilities to 26. (UP 26).
2) Hidden pair 59 at a1,c3 forbids 1278 from a1, 2 from c3.
3) c5=5 == c3=5 -- c3=9 == a1=9 -- g1=9 == g1=3 -- g5=3 == c5=3 More...
Looks like my solution is only a slight improvement over Clark's. They seem to be quite different in approach, though. I think Clark's solution is max depth 7 (at his step 13) and total sets 34. End of my proof is truncated - should say max depth 5 (at last step).
Hi Celia!
On a puzzle such as today's, I sort it out with multiple drafts - as they are many,many fc's available today - so the better ones do not necessarily jump out at me right away.
I think my approach is not guessing, but since 'guess' is not well defined, I cannot really answer that More...
Steve,
Our approaches are not that different. You have an extra 'money step' (your wraparound chain in step 3) but your other money steps are simpler than mine and you spend less time getting to them. Your step 5 is a simpler version of my step 9, your step 6 is a simpler version of my step 3 More...
11:29 ...and I can't tell you how many mistakes I made today. Have a good weekend everyone.
12.02 and all for a repeat photo
have a great day/night one and all
Hi Clark!
Of course you are correct in your analysis! I did not see the similarities - sorry!
Steve, thanks for your feedback.
Gooooooood Maen... 41:10--one of my fastest yet! :) Oh and my very first post.
July 20, 2007.
21/Jul/07 3:27 AM

SE=7.2
05/Sep/10 11:28 AM
24:14.
10/Sep/19 10:33 AM
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