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Tough Sudoku for 29/October/2005


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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7:02 (~3:00 to setup.. the rest to solve).. super easy.. the set will give you like half the board.. then there is a trick after that.. look to the rows for an answer.. i found only one problem area.. after that it was a piece of cake..
Not fast enough, Chaos my boy; I finished in just over 3 1/2 minutes; yess!!!
same as oct 22th, up to minor changings.
Dig in the sandbox (http://brunogreco.free.fr/bazar/sudoku/) to find :
- short hints for a proof or
- forbidding chains hints for a proof or
- a complete proof.
For new toughers, read first about Andrei's notation (it saves a lot of time and space).
Today's puzzle can be considered tougher than yesterday's : yesterday's proof needed only FCs (=forbidding chains) of length 4, while today's needed FCs of length 6. Comparison valid until someone finds a proof of today's puzzle involving only shorter chains.
Incredible ! You can now google for 'andrei's notation'!!! No more excuse for no one from now on !!!
OOPS it's midnight! Pumpkin time- Excuse the Halloween pun.
15:08 seems box/line reduction of 5's and 3's were helpful
Hi sweetie,
If you found a proof using only boxline reduction (which is a FC of length 2), it would be far simpler than mine ! Could you give us some more hints?
Too many guesses. Need to eat breakfast and will try again later. I thought this dog was going to AA.
God, please grant me the good fortune to run into the people I like, the senility to forget
the people I never liked anyway, and the eyesight to tell the difference.
20.31 and another drunken hound dog,crying all the time(well he will be after he's slept it off a little)Doggie aspirin and vitamin B shot required!
14:23 - bloomin marvellous for me - one day I'll be chaotic... but dont think I'll ever be a bucko.

It's the weekend!!!!!!!!!!!

I'm gonna bake bread and cakes and be a homely girl this weeknd, anyone for fruit loaf?
gb - just to make sure I've grasped this think/thick-linked...on your explanation, does it also follow that f9 cant be 1 as its thin linked to both e9 and f8?
lil - like that one!
lil from To you made me laugh :)
I got no time because i have no numbers
hi all must go hope this gets through!
such troubles trying to post last couple of days
Hi Deb, it's exact that f9=1 is thinlinked to both e9=1 and f8=1. But to conclude that f9 is not 1, you need to make sure that e9=1 and f8=1 are thicklinked, ie one at least of e9=1,f8=1 is true, ie e9f8 are only possible places for 1 in block Be8. Unfortunately, I didn't find where, in my proof of More...
gb - I didnt, beyond it being thin-linked to e9 and f8 - as c2 is to c8 and g2. I need to go back and go through it again - I've obviously not grapsed it yet....
finally finished
GB - not sure if this is the easiest or not...Normal techniques give you the following possiblities in row 9, A1678, B37, C13678, D1257, E27, F257, H36.
A 'hidden triple' of 2,5,7 can eliminate the 1 from D9, leaving D8=1, F8=4. From there you can finish the puzzle by removing all 7's from 9A,B,C or D2=4.
31:43; had to do this one twice, tried to save it the first time and it didn't save. Had to start all over. No guesses just looked for chain, it took me 15min. to find it but glad I did.
now that I have the numbers I wish I hadn't.. 23:39 ugh
bucko, just for once try to do it on paper and put down a real time there...
i second that notion!
Go for it Bucko! You are smarter than that!!!
Sorry Mike, I have same Row9 than yours at 51 filled cells, but I see no hidden triple : in row8 I have D147,F47. What is yours?
Enak,Bucko etc - lovely to have you back.You crack me up,even though you are a filthy liar about your times.With such talent for falsehood,you could surely pursue a career in politics?.....or law?
Hi all. GB, it seems I did this one without using chains. It is possible that I made a misstep in setup which turned out to be correct and helped me. I will try again later and see if I have the same result. Not a fast time though, too embarassing to divulge!
GB - I was just doing it again and realized my error. I need to look at it again. Hold on for a little while...?
Yes, I was jumping ahead. Forget the hidden triple, GB. Have to work out another method.
Hi fans!

I really love you, and you know what?
I tried the puzzle again on paper (had to copy it all by hand) and surprise, surprise, finished it in even better a time of 3:25 !!
Furthermore I'm sincerely happy about the fact, that this preposterous would-be queen and her king(?) have left these grounds. Let's all hope: forever!!
Down with monarchy!
GB - Seems like you have to use a chain - you can place a 4 in D2 and F8 by the following:
If F2=4 then D8=4, F8=7, E9=2, F9=5 and F5=5, which cannot be since they are in the same row, so therefore F2 is not 4 so D2 and F8 must be 4. But after this you are still not able to fully solve the rest with simple eliminations. At least I think so...
Well, I did it a second time, more than twice as fast but I'm still not divulging, and I didn't use any apparent chains.
Come on, Blep!
You're allright! Just tell us you did it twice as fast, but it still took you 18 minutes.
Nothing to be ashamed about...
Shameless Bucko. I don't care how you cheat your time, just stop making fun of serious people here.
Blep - I'm interested in your solution since I am stuck on solving w/o using any 'advanced' methods. Can you give a hint that breaks it open? Thanks -
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