Tough Sudoku for 20/February/2007

Nice beach, wish I was there, snowing here this morning.

6:10 Maen One error

First! - I think. Lovely relaxing pic - makes me want to walk down to my beach.

Hello everybody from the Czech Republic.

walking on a beach wow how I can't wait for summer.

This puzzle seems to be monstrous to PROVE, but not necessarily hard to SOLVE - especially if one chooses to guess.

I was at a wrestling tourny for my two youngest sons yesterday, so I had a sudoku-free day!

Since the weather is finally promising to improve, it is likely that I will be more scarce both here and in the blog.

A perfect beach picture--lucky couple. Have a great day/night, everyone.

very tough today...! maybe proof is long. Rating 8.9/10 in SE. SudoCue use three table conflict, for me Table Conflict is not better than Region Forcing Chain in SE. Every tough ALWAYS can solve by CHAINS...

I doubt that Matt and Nicole like anyone to interrupt there privacy and have this picture without thier permission while they are walking alone on such very quite beach.
By the way What do you think they talk about?????
Nice maEn to all

8:49
I would like to be on this beach...

Wadgy...I know what they were talking about.

I took the picture. It was 7-30am Thursday morning 14th Dec 2006 and Nicole was going into hospital in about half an hours time to be induced to have her baby, Kiarah. Of course, we all know now that it took another two days before she was born.

8:08

What a beautiful picture. It is enough to give one 'spring-fever'!

Have a great day everyone.

Good afternoon to all! Ever the watchful parent Deb? Nice photo!

Beautiful picture.

Wagdy Camel from Egypt, the are probably talk about that day lasting forever, or perhaps where they left the keys to the car.

First time I have managed to complete a tough. Maybe I will tackle tomorrow's as well.

Nice beach scene. It has even been a bit cold this week in Florida to go to the beach.

Hello Eliska nice to hear from someone from the Czech Republic. Lovely photo Deb, you could put this in Kiarah's album as a ' before you were born' photo. A very hot 38%C here this afternoon a walk on a beach with a cool breeze would be lovely.

This was not too difficult and that is not usually the case with the toughs.

About 40 mins today, all proven. My best yet

Possible proof for tough of 2/20/07:
1) Start at 23 filled. Unique Possibilities to (UP) 27.
2a) hidden pair 29 at g28, forbids g2=135, g8=145
2b) locked 5's at e23, forbid e46=5.
2c) locked 5's at gh4, forbid g56, i5=5. UP 29.
3a) locked 4's at g56, forbid g9=4.
3b) g9=5 == g9=1 -- i7=1 == i7=9 -- i1=9 == b1=9 -- b1=6 == d1=6 -- d8=6 == h8=6, forbids h8=5.
3c) locked 5's at bc8, forbid b9=5.
3d) b7=2 == h7=2 -- g8=2 == g8=9 -- i7=9 == i7=1, forbids b7=1.
3e) b8=5 == c8=5 -- c56=5 == {pair c56=23} -- a5=23 == a5=7 -- a9=7 == a9=4 -- a8=4 == {pair a8b7=23}, forbids b8=23.
3f) c8=5 == {pair c56=23} -- c12=23 == {pair c12=14}, forbids c8=14.
3g) locked 1's at b89, forbid b123=1.
3h) pair 23 at b37, forbids b1=2, b26=23.
3i) pair 69 at b12, forbids a2=9, b6=9. UP 34.
4) hidden triple 235 at a5b56, forbids a5=7. UP 81.

HI Dave!
I do not understand step 3f. I have c56=5 == c8=5, which would yield c56=5 == c56=pair 23, as you noted in step 3e, but not c8=5 =={pair 23 at c56}.
Step 3e is ok. You can shorten it a bit with:
{Hidden pair *15 at bc8} *==* b9=1 -- b3=1 **==**{pair 23 at **b37} forbids b8=23, but I am now using different strong sets.

The only proof that I have, so far, to this one, uses depth 11. I have not returned to it to find a less deep proof. If you can make the elimination of 14 from c8 stand up with a legit chain, you could very well be on to a much better path.

I have whittled this one down to depth 7, but the proof is still ungainly... Perhaps it is a good topic for the blog...

17:12

telkysazu jmxyakw dbafl osem hemdcuzxt hkyjlqr vdyzebi

bsfgekiu blhsnckmw mdbqar pqladubwc hvgxunb tugjbsz gfwil http://www.ujocdw.lwyiqop.com

Took about 40 mts. Good one.

Dec. 17, 2007.

SE=8.9

16:08.