Sudoku Puzzles

Cute dog Deb, his eyes look a bit green

6:20 another relatively easy one Maen

Holly's got wonderful green eyes. Have a great day/night, everyone!

A green-eyed dog??? 5:26

Good Maen to all, and Hi Holly! I think we've seen you before, haven't we?

I hate when I screw up the possibilities. I had to restart this one twice. I must be tired!

7:45. Cute dog. Bet he's not spoiled, is he? Maen everyone.

15.38 Cute dog. I have a Chesapeake Bay Retriever named Holly; she has as much energy as a Jack Russel.

58:58

Only needed one guess for this one! Cute pooch.

10:41 mAen, all! Cute dog. :)

interesting!Seems dificult but at the end no so much!

Very nice wrap around chain today:
1) Start at 23 filled - the given puzzle. Unique Possibilities to 25 filled. (UP 25).
2) b1=8 == b46=8 -- ac5=8 == a5=2 -- c5=28 == c5=9 -- b46=9 == b1=9 forbids b1=57,ac4c6=89,c6=2
UP 33
3) fc on 8's: b4 == h4 -- h3 == a3 forbids b1,a5=8 UP More...

Step 2 writes perhaps more clearly as a matrix:
b1=8 b46=8
0000 aa5=8 a5=2
0000 cc5=8 c5=2 c5=9
b1=9 00000 0000 b46=9
Since column 1 is proven strong, so are the other columns: Forbids b1=57,c6=2, ac4c6=89.

The clue to finding this chain is easy, as one can see upon inspection that b1<>89 forces hidden pair 89 at b46 which forces both ac5=2.

Bloody-hell Deb, ANOTHER photo! How many have you sent in????

Hi Everyone,

Sorry about last night. Huge problems

Definitely got to move hosting company!

Anyway, everything should be ok for now. Let me know if you can't log it etc.


Gath

BTW - at UP 25 there exists also a very nice 2 degree of freedom almostlocked set type elimination group. This is talked about at some length in some sudoku forums. This is what exists:
ALS type elimination:
a3= 1258, a2= 1275, a1=2578, b2=57, a5=28 forbids :
a489=8, b1=57, c12=5
The More...

The idea being that if there exists a hidden tuple, there exists a naked tuple in the same large container. The same also is true for ALS type eliminations: If there exists a naked ALS elimination, there exists a hidden ALS elimination. Which one is easier to see depends on the person looking, at size of sets.

I missed one more elimination group above:
Forbids: a489=8, b1=57, c12=5, a89=1. Sorry about the omission.

Perhaps one more note on the ALS type elimination group shown above:
These types of eliminations, albeit rare, can result in a large bounty of eliminations, as it is essentially two or more wrap around type 'chains' all in one group of cells. Some of the supposed most difficult sudoku's that are celebrated in some forums can be tackled successfully with this technique.

-- Hi everyone, new to Sudoku. I started playing 3 days ago, and I am beating the 'tough' level fairly quickly now. Am I correct in assuming that the number appearing before posts is the amount of time it took people to complete the puzzle? Also, what does MAEN mean?

And does anyone complete the puzzle 100% without ever using the 'Check moves' button?

Cute dog??!! Scary looking, you mean!

With people all over the world using this site, maen is a greeting used to describe which part of the day it is where you are. Capitilize the letter that works for you. Morning, Afternoon, Evening, Night.
Yes, the number used in posts is the time it took that person to solve the puzzle.

5:21

hi
i'm first

Steve,
I don't understand the 3rd link in your 1st chain: ac5=8==a5=2. At 25, I have a 28 in a5 and 289 in c5. Did I miss something on setup?

Most of the time I can follow the chains, even your 1st and 3nd links today I can 'get', the 3rd one is just too far out for me. Can you explain it a ilttle more?

TIA.

13:02 after setup. Cute doggie. Interesting how the ocular red reflex came out green!

HI Jeff!
The chain that I present uses some shorthand, as the chain really presents better as a matrix. As you said, a5=28, c5=289. Clearly then, a5=8 == a5=2.
I used the shorthand to show that b46=8 -- ac5=8:
This is because the chain requires that 8 in b46 forbids the 8's from both a5 and c5. Clearly, then b46=8 also -- c5=28, since a5=28. Hopefully this helps.

Angie, thanks for the response.

Steve, like ... wow. What you wrote is Greek to me (no offense to any Greeks). Besides the eBook for $17, (and I already subscribed to the newsletters today), is there a source I can understand what this terminology means?

(i.e., a5=28, chain, forbids, etc.)

Thanks.

Steve,
Thanks for the clarification, but alas, I still do not 'get' that step. Tommorow is another day to learn...

I was hoping to master forbiding chains before I tackled the matrixes you use. Are the matrixes easier? Or only sometimes?

Are there always or maybe sometimes More...

Ricco,
If you comb the tough archives for the last couple months and follow the proofs link at the bottom of the page, you will get a pretty good understanding of the notation.

If that does not work, post again, someone will help. If the experts do not reply, I will try my best to explain it as I understand it(which I think is 99% accurate :-)).

Hi Jeff!
Matrices for me are not easier. They merely make the information found more readable - at least in the eyes of this beholder.

The way I found the chain follows:

Notice the almost hidden pair 89 at b46 (both 8's at 9's in column b are limited to b146)
Clearly, upon More...

The logic as a forbidding chain like structure:
Note the triplet ac5=289 in two cells.
Note the symetric b1=8 == b46=8 and b1=9 == b46=9.
Thus:
b46contains8 == b46contains9
=> ac5=pair28 == ac5=pair29
=> b46contains8 -- b46contains9
=> b1=8 == b1=9(forbids b1=57), More...

Hi Everyone,

Friday afternoon here, so I thought I'd load up some new smilies for you to play with. What can I say


Gath

19:35.. Hello Holly!! You are a pretty girl!!

Gath... thanks for the cute new smilies!!

Gath - thanks for all the hard work - really look forward to my daily sod-fix.
Wish I had eyes the same colour as 'Jack'

Ricco,
Like you,
I was lost, and now am found!
http://brunogreco.free.fr/bazar/sudoku/01-10.htm
ex plains everything. (well it did for me, anyway)

took exactly 10 minutes to see this 'holly' with green eyes..
cheers

Personal best 23:15, only 10 guesses and 6 mistakes

Woof!