Tough Sudoku

Nice Dolphins

Dinner time.

so long and thanx for all the fish

If the ladder isn't high enough, why don't they use a different one? Why stand on tip toes? Do those few inches really make a difference?

Truly graceful animals.

yum

Reminds me--we're having seafood tonight; a pleasant change from turkey. Cheers all, and in case I don't check in tomorrow, Happy New Year!

As luck would have it, the current blog page is timely again:

A proof for tough sudoku of 12 30 06:
1) Start at 22 filled - the given puzzle. Unique Possibilities to 27 filled. (UP 27).
2) Hidden triple 189 at a23,b3 forbids: ab1=8,a2=456,a3=4, b3=47 UP 57
Note: in row 3 therefor in box a2, 8's are locked at ab3, in box a2 9's are locked at a23b3 and 1's are locked at ab3 to form this hidden triple in box a2.
3) Coloring on 7's: Note strong 7's in both column b and in row 6:
fc on 7's: b1 == b5 -- c6 == g6 forbids g1=7 UP 81
Sets:5. Max depth 3 at step 2. Raring: .10

Raring??? Rating .10

Great photo. Whose is it?

Repeat photo. I remember this one because I did it as a jigsaw.

8:54 Not to hard today.
To All: Have a Great New Year, I'm off to Cuba for a week, and I’ll try and take a picture worthy of display.
All the best in the New Year.
Trevor

Good afternoon to all! It certainly is a repeat photo Martha, several times over. We've seen it at least three times before, and those dolphins must be dead by now hanging in the air all this time!

maeN! 36:15

Steve! My soltn followed the thinking of your proof all the way up to UP 57. At that point I studied the cell c3. It contains either 4 or 7. It can't be a 7, for then row 6 would have its 7 on column g, and there would be no place for the 7 in the bottom right 3x3 box. A very small difference, I guess. And your argument was meant to be educational as well!

Anyway it felt good to solve a tough one without inserting all the possibilities for all the cells for a change. I need to play the tough ones more.

Cheers,

Jyrki

Hi jyrki!
Thanks for the alternate idea. Your idea is also 'coloring'. Here is how that step would be presented as an fc.
One can replace my step 3 with jyrki's idea:

3) coloring on 7's: Note strong 7's in box h2,and in row 6.
fc on 7's: ghi3 == g1 -- g6 == c6 forbids c3=7 UP 81

can't do that on a day like today around here...

w.w.

Today like yesterday it is very easy, tomorrow i hope more difficult.

Hi everyone! I remember this pic. as it was one of the very first pictures i saw when I first came on this site over a year ago now! wow time has really gone fast, cannot believe it is nearly another year, and boy what a year it has been, my wish for the new one is not to be as hectic and busy as this one????

Canuk Greg, maybe they are frozen to keep them fresh hehe. Have a happy and healthy 2007 everyone.

6:35

22:20

Nov. 10, 2006.

SE=6.6