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 

5 JUne difficult -has this technique got a name?
Goto page Previous  1, 2
 
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Daily Sudoku puzzles
View previous topic :: View next topic  
Author Message
jLo



Joined: 30 Apr 2007
Posts: 55

PostPosted: Thu Jun 07, 2007 4:02 am    Post subject: Reply with quote

TexCat wrote
Quote:

I certainly agree that there is no need for w-wings on this puzzle. Dulaby's xy-wing solves it nicely. I cannot see any skyscraper on 1's though.


I see the XY-Wing, but only after row 3 is cleaned up. I get to here -

Code:

+---------------+-----------------+---------------+
| 17  6    378  | 1478  5    48   |  49  2    39  |
| 5   18   238  | 9     146  2468 |  7   146  36  |
| 9   4    27   | 3     167  26   |  8   16    5  |
+---------------+-----------------+-------------- |
| 6   5    1    | 2     8    7    | 3    9    4   |
| 8   2    9    | 46    46   3    | 1    5    7   |
| 3   7    4    | 5     9    1    | 26   68   268 |
+---------------+-----------------+-------------- |
| 24  38   5    | 468   346  9    | 246  7    1   |
| 247 138  6    | 478   1347 5    | 249  48   289 |
| 147 9    78   | 14678 2    468  | 5    3    68  |
+---------------+-----------------+---------------+


How do you go about solving Row 3 to set up the XY-Wing? The best I could
do was see that if R3C3=7 then R7C2=3 and R7C5=3, so R3C3 cannot be 7 . . .
Is there another method?

I don't see the Skyscraper either.
Back to top
View user's profile Send private message Yahoo Messenger
Mogulmeister



Joined: 03 May 2007
Posts: 700

PostPosted: Thu Jun 07, 2007 10:17 am    Post subject: Reply with quote

I don't see a skyscraper on 1's but perhaps cg meant x-wing on 1's which I see you've already applied j-Lo. (Although that doesn't remove the 1 in r2c5)

Have a look at row 8 and you'll see that there is a hidden pair. This will create a single on row 3 which in turn will remove the 2 in r2c3. You can now build that xy wing.
Back to top
View user's profile Send private message
cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Thu Jun 07, 2007 6:05 pm    Post subject: Reply with quote

I always thought skyscrapers could be horizontal as well as vertical - they are if you rotate the page! Maybe vertical skyscrapers are y wings and horizontal ones are x wings. Anyway, using George's grid on his first post, there are two 1's in col. 2 and two in col 8. By my reckoning since the two 1's in Row 2 line up. one of these has to be a 1. Therefore the 1 in R2C5 is eliminated. No???
Back to top
View user's profile Send private message
Mogulmeister



Joined: 03 May 2007
Posts: 700

PostPosted: Thu Jun 07, 2007 6:58 pm    Post subject: Reply with quote

cg,

Yes skyscaper can be vertical or horizontal. However they are strong links of different length that both have a node on the same row/column.

I see where you're driving at but your row 2 has actually got 3 boxes with 1 in it so it is not a strong link. The other problem is that for a candidate to be eliminated it must be able to be "seen" by the two ends of the skyscraper.

cg - if you want to see a graphic example of a skyscraper look at the one that is illustrated in Mesmin's puzzle in this thread
[url]
http://www.dailysudoku.com/sudoku/forums/viewtopic.php?t=1860&sid=9cb62644c9357068f48772c4a472f413 [/url]

The skyscraper is in pink, the eliminated 5's in orange.
Back to top
View user's profile Send private message
csc



Joined: 03 May 2007
Posts: 14

PostPosted: Thu Sep 20, 2007 3:23 pm    Post subject: 5 jun 07 most straightforward solution Reply with quote

I've just completed this puzzle, after having read the discussion on it. I was at the same position as George, when I got stumped. Seems to me that the most straightforward route is as suggested by Steve R. After having identified the 13 hidden pair, and getting the 7 in r3c5, you need only 1 xy wing (to eliminate 8), to complete. Thanks Steve.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Daily Sudoku puzzles All times are GMT
Goto page Previous  1, 2
Page 2 of 2

 
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