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Tough Sudoku for 15/October/2006


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

  1 2 3 4 5 6 7 8 9
Check out the latest post in the Sudoku Forum

Sudoku Solving Techniques

Submitted by: sudoku lover

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Impressive!! Who does have it for their backyard?
More fantastic Utah scenery. Thanks.
Very Impressive. Great photogrphy.
8:26 Looks like a face up there.
I would love it !
A worthy tough one today:

1) Start 23, Unique Possibilities to (UP) 27.
2) Hidden pair 59 at h78 forbids h7=1246, h8=246. UP 28.
3) x-wing: 9s at bd4, bd5 forbid b79=9, d78=9.
4) Naked triplet f9=27, g9=267, i9=267 forbids bc9=267.
5) a1=1 == a2=1 -- a2=5 == a78=5 -- b9=5 == More...
Yes, I would love it too ! Some people have all the luck ! Good Mean everyOne!
I don't know who owns the house at the bottom of the cliff, but I admire their setting everytime I drive by. Unfortunately, our move to this area is too late to have any land available for sale in the Dry Fork Canyon area, but I can still enjoy others' views. It stirs my imagination to think of exploring that cave sometime.
No time to pare this one down:(also forgive likely typos! Please!)

Possible solution to tough sudoku of 10 15 06:

1) Start at 23 filled - the given puzzle. Unique Possibilities to 27 filled. (UP 27).
2) Hidden pair 59 at h78 forbids h7=246 and forbids h8=1246 UP 28
3a) More...
Hi Everyone
This is my first posting here. I have a question, what does 'start at 23 filled' mean, also, 'a-1=1', etc. I'm not sure what the letters stand for.
I see the face that you see, Nina. Kinda looks like a skull.
Yeah, building your house at the bottom of a cliff is a great way to save on funeral expenses.
Possible proof of today's not so tough.
Max classical depth 4.

1) Start with 23, UP 27
2) Naked Triple: fgi9=267 => ~bc9=267
3) Locked: a54=3, gi9=6, b645=9, d54=9 => ~(a87=3, ghi8,gh7=6, b97,d87=9)
4) Hidden Pair: h87=59 => ~(h8=24, h7=124), UP 28
5) Locked: ghi8=4 More...
note: step (8) could be written:

b9=8 == b9=5 -- NT: a875=257 == a5=8
=> ~b654=8

a somewhat simpler version of Steve's step (3f)
- but what depth is it?
What a joy today's beautiful pictures have been. I too see that which looks like a skull. Thanks to all of the great photographers for sharing their veiws of so many superb sites.
Hey, this picture could have been taken from my back yard (but it wasn't)
Kathy, Here's a beginners guide to the language used on this site.

The sudoku board is numbered like the chess board columns a-i starting from the leftm and rows 1=9 Therefore a1 is your bottom left square,

C=column R=row B=block The blocks are labeled according to the middle More...
At least Utah has some scenery... because let's face it... it's nothing else.
Not a bad 'backyard', but I'll take what mountains I have.
Thanks for the photo Wilodene
59:22, too slow...! nice picture.
Proposals for possible modifications of Sudoku:

1)Instead of starting with given numbers, replace some of these with cells where a choice two of candidates is given.

2)'Liars' Sudoku. Have some limited selection of the givens be false.

3) FC Sudoku. Replace some of the givens forbidding chain strong sets

Maen all on sunday am
Let's hear it for fi. I find that much easier to understand than the mathmatical proofs (without intending to cast any slight upon those who post them nor those who can follow them).

When setting up, I enter possibilities block by block and while doing so keep a weather eye open for what More...
Oct. 20, 2007.
21/Oct/07 2:00 AM

05/Sep/10 10:12 PM
1.SST to UP27
2.(257=8)a78b9-(8=279)b456 > -27a45b6 UP38
3.(3=257)afi8-(5)b9=(59')e79 > -3e7 UP81.
11/Mar/11 2:50 AM
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