Tough Sudoku

puppy!

9:05 cute pup

What a grand little puppy is it a border collie???

WE had fog here till 1 am and now it is about -3 so who knows what it will be in the am as it is about 1 am

oops i should have said 1 pm sori

cute puppy - 13:13 through a 'comedy' of errors and mouse errors...

A yawner today:
1) Start at 22 filled - the given puzzle. Unique Possibilities to 23. (UP 23)
2) Hidden pair 26 at e3,f1 forbids e3=458 and f1=478. UP 46.
3) i3=3 == i7=3 -- c7=3 == c2=3 forbids b3=3,h2 =3. UP 47.
4) i3=5 == i6=5 -- e6=5 == e2=5 forbids d3,h2=5.UP 53.
5) a5=9 == a7=9 -- i7=9 == i6=9 forbids bc6=9. UP 81

Total sets 8. Max depth 2. Difficulty rating 4*.03 = .12.

When you get as far as you can with simple moves, look for forbidding chains in the 7s

Made it up to 46 cells filled, then needed a guess. The rest fell into place.

What big eyes you have, Meggs!

Is a try ,which is proven wrong,not a legitimate technique?

not very tough but i dunno why took 20 mts to see this big eyed puppy called meggs.....may be the odd time i work on this puzzle..normally i never stay up this late..its now 11pm here in india and i could come near the pc only now!!
cheers

31:41

21:37

Good mAen to all. Just got to the Tough and rewarded with Meggs. Photographs well, because it doesn't look very old!!

mAen,

Cute puppy, looks like its eyes are blue?

What is a 'forbidding chain'?

Cute Meggs!

10:14 and truly tough. several guesses. good mAen all!

15.53 Hey Meggs - cute pooch!

Good maEn cute puppy.

Cute Meggs! I thought the Tough was TOUGH today. Maybe I am just tired. Good maeN to all.

8.56
cute little meggs
have a great day/night one and all

Hey Steve,
how do you work out the A5=9, etc. I see how the connection is made, but I don't know why it forbids BC6=9.

What an adorable pup...I'm addicted to border collies

10:57 I guess I'm a slow thinker.

Hi Amy!
If a5=9 then bc6<>9. If, though, a5<>9, then a7=9 which forbids i7=9 which forces i6=9. But i6=9 also prevents bc6=9. Thus, in any event, since at least one of a5=9 or i6=9, we can have no more 9 at bc6.

4:30 good time

thank goodness there was cute Meggs to look at instead of barbed wire. This was a tough tough

Such blue eyes!!! Assuming from the comments that this is a border collie, do they usually have blue eyes or is it a rarity?

Hi Steve from Ohio,
I'd really appreciate it if you could explain your steps 3) and 4). I've looked and looked and can't work out WHY the i3 i7 c7 c2 forbids b3 and h2 being 3. I'm hoping you might be able to give me the next logic step in sudoku that I've been searching for!

My steps were the same (approximately) to Steve's except my step 5 was a y-wing of 459's in e2,e5 and d4 forbidding d2=5. Maybe a yawner for you, Steve, but it took me a while to find the chain of 3's. I don't have your 'vision'.

Hi Ford,
If you read the result of the chain as, 'If i3 is not 3 then c2=3,' then you can see that because cell h2 shares a box with i3 and a row with b2, and i3 or c2 is 3, h2 can't be 3. Likewise for b3. Does that help? You might try looking at Bruno's explanations, following the proofs link on this page.

07/04/06 poss , 2 guesses (both wrong)

phrals tfzncor qxmidwnt emrdp ioxmpjesa epqnhiv xagd

ezxyav dntfovx bhkg kfuwshptx xsmwgc eqhgobt fbjdq http://www.foxesb.msdbx.com

Aug. 4, 2007.

SE=6.6

21:52..