dailysudoku.com Forum Index dailysudoku.com
Discussion of Daily Sudoku puzzles
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Set A Puzzle 30

 
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Puzzles by daj
View previous topic :: View next topic  
Author Message
daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Fri Nov 28, 2008 10:36 pm    Post subject: Set A Puzzle 30 Reply with quote

Code:
 +-----------------------+
 | 5 . . | . . . | 7 . 9 |
 | . 1 3 | 7 . . | 8 . 4 |
 | . 4 . | . . . | . . . |
 |-------+-------+-------|
 | . 3 . | 4 . . | . 7 5 |
 | . . . | . . . | . . . |
 | . . . | . . 5 | 3 8 1 |
 |-------+-------+-------|
 | 3 8 . | . . 6 | . . . |
 | . . . | 3 . 1 | . 4 8 |
 | 1 9 . | 2 . 4 | . 5 . |
 +-----------------------+

Play this puzzle online at the Daily Sudoku site
Back to top
View user's profile Send private message
tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Sat Nov 29, 2008 3:00 am    Post subject: Reply with quote

I found a three-step solution: An ER followed by two xy-wings.

Hint:
Quote:
ER on <6> in box2 with strong link on <6> in row6, a xy-wing on <289> and then on <689>.

Ted
Back to top
View user's profile Send private message
storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Tue Dec 09, 2008 10:14 pm    Post subject: Reply with quote

that ER that Marty mentioned had me evaluating this puzzle again and this came up.

notice the "*" marked cells belown contain the almost UR {2,5} in r58c23
Code:
.------------------.------------------.------------------.
| 5     26    268  | 168   4     238  | 7     13    9    |
| 29    1     3    | 7     5     29   | 8     6     4    |
| 7     4     689  | 1689  16    389  | 5     13    2    |
:------------------+------------------+------------------:
| 689   3     169  | 4     16    89   | 2     7     5    |
| 28   *25   *125  | 18    3     7    | 4     9     6    |
| 4     7     69   | 69    2     5    | 3     8     1    |
:------------------+------------------+------------------:
| 3     8     4    | 5     9     6    | 1     2     7    |
| 26   *256  *256  | 3     7     1    | 9     4     8    |
| 1     9     7    | 2     8     4    | 6     5     3    |
'------------------'------------------'------------------'

notice also that an inference can be made.

if the 1 in r5c3 is not there then the 6's in r8c23 have to be true. and vice versa. this is a strong link, they both can't be false. (1)r5c3 = (6)r8c23...ok?

lets put this little chunk to work

Code:
.------------------.------------------.------------------.
| 5     26    268  | 168   4     238  | 7     13    9    |
| 29    1     3    | 7     5     29   | 8     6     4    |
| 7     4     689  | 1689  16    389  | 5     13    2    |
:------------------+------------------+------------------:
|#689   3     169  | 4    #16    89   | 2     7     5    |
| 28    25   #125  |-18    3     7    | 4     9     6    |
| 4     7     69   | 69    2     5    | 3     8     1    |
:------------------+------------------+------------------:
| 3     8     4    | 5     9     6    | 1     2     7    |
|#26   #256  #256  | 3     7     1    | 9     4     8    |
| 1     9     7    | 2     8     4    | 6     5     3    |
'------------------'------------------'------------------'

now we can form a w-wing Exclamation Exclamation Exclamation yep. see the strong links on 6 in column 1?

we now have a w-wing {1,6} via strong link on 6 in column 1. this connects our pseudocell {1,6} to the {1,6} in r4c5. 1's are the pincers eliminating the 1 in r5c4.

singles to finish.

hopefully this image will be helpful.


I circled the w-wing pair in green ! and I connected the links on 6 in blue, the red is the pincer elimination.

what this shows is how the {1,6} pseudocell is formed via the almost UR and how they can be encompassed because they are part of the UR structure thus forming the strong link necessary, like a bivalue cell Idea

I will take a shot at notating this.

(25UR)r58c23[(1)r5c3 = (6)r8c23] - (6)r8c1 = (6)r4c1 - (6=1)r4c5; r5c4 <> 1
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Puzzles by daj All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group