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 

LA Times / Freep - June 27, 2008

 
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Other puzzles
View previous topic :: View next topic  
Author Message
keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Fri Jun 27, 2008 9:57 pm    Post subject: LA Times / Freep - June 27, 2008 Reply with quote

Not yet solved:
Code:
Puzzle: FP062708
+-------+-------+-------+
| . . . | . 4 2 | 7 . . |
| . 2 . | . 1 . | . 6 4 |
| . 1 . | . . . | 5 . . |
+-------+-------+-------+
| 1 . . | 7 . . | 6 . . |
| 6 7 . | . . . | . 2 5 |
| . . 2 | . . 8 | . . 1 |
+-------+-------+-------+
| . . 4 | . . . | . 5 . |
| 2 9 . | . 6 . | . 3 . |
| . . 7 | 2 8 . | . . . |
+-------+-------+-------+
Keith
Back to top
View user's profile Send private message
Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Fri Jun 27, 2008 10:15 pm    Post subject: Reply with quote

This one is surprisingly tough, unless I'm missing something. It took me 5 steps: XY-Wing; Sashimi Swordfish; Turbot Fish (or ER); XY-Wing; W-Wing.
Back to top
View user's profile Send private message Visit poster's website
keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Fri Jun 27, 2008 10:47 pm    Post subject: Reply with quote

Asellus wrote:
This one is surprisingly tough, unless I'm missing something. It took me 5 steps: XY-Wing; Sashimi Swordfish; Turbot Fish (or ER); XY-Wing; W-Wing.


You solved it? Basics get me to here:
Code:
+----------------+----------------+----------------+
| 3589 358  6    | 3589 4    2    | 7    1    389  |
| 7    2    3589 | 3589 1    359  | 389  6    4    |
| 4    1    389  | 389  7    6    | 5    89   2    |
+----------------+----------------+----------------+
| 1    3458 3589 | 7    2    349  | 6    489  389  |
| 6    7    389  | 1349 39   1349 | 3489 2    5    |
| 39   34   2    | 6    5    8    | 349  7    1    |
+----------------+----------------+----------------+
| 38   368  4    | 139  39   1379 | 2    5    679  |
| 2    9    1    | 45   6    457  | 48   3    78   |
| 35   356  7    | 2    8    349  | 1    49   69   |
+----------------+----------------+----------------+
There is an XY-wing 48-49-89 that takes out <8> in R2C7. With coloring on that same wing, you can take out <8> in R3C3. Leaving me here:
Code:
+----------------+----------------+----------------+
| 3589 358  6    | 3589 4    2    | 7    1    389  |
| 7    2    3589 | 3589 1    359  | 39   6    4    |
| 4    1    39   | 389  7    6    | 5    89   2    |
+----------------+----------------+----------------+
| 1    3458 3589 | 7    2    349  | 6    489  389  |
| 6    7    389  | 1349 39   1349 | 3489 2    5    |
| 39   34   2    | 6    5    8    | 349  7    1    |
+----------------+----------------+----------------+
| 38   368  4    | 139  39   1379 | 2    5    679  |
| 2    9    1    | 45   6    457  | 48   3    78   |
| 35   356  7    | 2    8    349  | 1    49   69   |
+----------------+----------------+----------------+
And, I am stuck.

Keith
Back to top
View user's profile Send private message
Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Sat Jun 28, 2008 12:48 am    Post subject: Reply with quote

Keith,

That r3c3 elimination can also be seen as a Kite. You need the Sashimi Swordfish. It's in r235. See if you can spot it.
Back to top
View user's profile Send private message Visit poster's website
storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Sat Jun 28, 2008 1:20 am    Post subject: Reply with quote

after basics

Code:
.------------------.------------------.------------------.
| 3589  358   6    | 3589  4     2    | 7     1     389  |
| 7     2     3589 | 3589  1     359  | 389   6     4    |
| 4     1     389  | 389   7     6    | 5     89    2    |
:------------------+------------------+------------------:
| 1     3458  3589 | 7     2     349  | 6     489   389  |
| 6     7     389  | 1349  39    1349 | 3489  2     5    |
| 39    34    2    | 6     5     8    | 349   7     1    |
:------------------+------------------+------------------:
| 38    368   4    | 139   39    1379 | 2     5     679  |
| 2     9     1    | 45    6     457  | 48    3     78   |
| 35    356   7    | 2     8     349  | 1     49    69   |
'------------------'------------------'------------------'


I will go along with the xy-wing to remove 8 from r2c7
coloring 8...
ER {3}
which leads to this...

Code:
.------------------.------------------.------------------.
| 3589  358   6    | 3589  4     2    | 7     1    #389  |
| 7     2    #3589 |#3589  1     359  | 39    6     4    |
| 4     1     39   |3-89   7     6    | 5    #89    2    |
:------------------+------------------+------------------:
| 1     3458  589  | 7     2     349  | 6     489   389  |
| 6     7    #389  | 1349  39    1349 |#3489  2     5    |
| 39    34    2    | 6     5     8    | 349   7     1    |
:------------------+------------------+------------------:
| 38    368   4    | 139   39    1379 | 2     5     679  |
| 2     9     1    | 45    6     457  |#48    3    #78   |
| 35    356   7    | 2     8     349  | 1     49    69   |
'------------------'------------------'------------------'


there is a cycle on 8 marked
(8)r2c4=(8)r2c3-(8)r5c3=(8)r5c7-(8)r8c7=(8)r8c9-(8)r1c9=(8)r3c8; r3c4<>8

one coloring move removes 9 from r1c1.
xy-wing {3,4,9} removes the 9 in r5c7
Back to top
View user's profile Send private message
Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Sat Jun 28, 2008 4:05 am    Post subject: Reply with quote

The Sashimi Swordfish can also be viewed like Norm's 8-cycle of weakly connected conjugate (strong) links, though it is shorter:
(8)r3c8=(8)r3c4 - (8)r2c4=(8)r2c3 - (8)r5c3=(8)r5c7; r4c8<>8
The missing Swordfish bit is r5c8. The result is the same as Norm's cycle.

The full details of my solution path, after the XY-Wing and Sashimi Swordfish, are:
[3] Turbot Fish (or Color Wing or ER) in c1-r1-b3 removes <9> from r6c7
[4] XY-Wing, pivot r6c7, removes <9> from r5c7 (Same as Norm's)
[5] 34 WWing in r46, <4> strong link in c2, removes 3 from r4c9
Back to top
View user's profile Send private message Visit poster's website
storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Sat Jun 28, 2008 7:53 am    Post subject: Reply with quote

I have to credit Ravel for his views on catching useless kites as in the cycle example, which combines a useless kite on 8 with two shorter conjugate strings.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Other puzzles 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