SudoCue Users Forum Index SudoCue Users
A forum for users of the SudoCue programs and the services of SudoCue.Net
 
 FAQFAQ   SearchSearch   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

One-Trick Pony 8-23-07: Did I make a lucky mistake?

 
Post new topic   Reply to topic    SudoCue Users Forum Index -> Help Me! I'm stuck!
View previous topic :: View next topic  
Author Message
JLynn
Hooked
Hooked


Joined: 25 Jan 2007
Posts: 52
Location: Alaska

PostPosted: Fri Aug 24, 2007 2:56 am    Post subject: One-Trick Pony 8-23-07: Did I make a lucky mistake? Reply with quote

I'm not exactly stuck on this puzzle, but I do have a question about a technique I may have abused. This puzzle, according to sudocue, requires an XYZ-Wing and two hard steps.

This is the point where SudoCue uses an XYZ-Wing:

Code:
.------------.------------.------------.
| 3   1   4  | 7   59  2  | 8   6   59 |
| 59  6   2  | 8   1   4  | 7   3   59 |
| 7   8   59 | 3   6   59 | 2   4   1  |
:------------+------------+------------:
| 2   7   59 | 1   4   6  | 59  8   3  |
| 8   3   1  | 59  7   59 | 6   2   4  |
| 59  4   6  | 2   8   3  | 159 19  7  |
:------------+------------+------------:
| 46  2   7  | *569 3(5)9 1  | 34  *59  8  |
| 16  5   3  | 4   29  8  | 19  7   26 |
| 146 9   8  | *56  235 7  | 34  1[5]  26 |
'------------'------------'------------'


I found the same wing SudoCue did, which I've starred (thanks, BTW for the pairs filter Ruud). We both eliminated a 5, but the 5's we eliminated were different. Sudocue's elimination is in parentheses, mine in square brackets. SudoCue's elimination required two more hard steps. My elimination sent the puzzle straight to singles. This is why I ask if I made a lucky mistake. I'm still trying to figure these wings out.
Back to top
View user's profile Send private message
rep'nA
Hooked
Hooked


Joined: 19 Jan 2007
Posts: 49
Location: Union City, California

PostPosted: Fri Aug 24, 2007 4:33 am    Post subject: Reply with quote

It's a lucky mistake. The elimination cell for an xyz-wing has to see all three cells, not just the two wings. In this case, r7c5 sees all three and so the elimination of 5 is possible, but r9c8 only see two of the three cells and so the elimination does not follow from the pattern.

However, there is a move that will eliminate both 5's and hence crack the puzzle, namely an xy-chain
Code:

(5=9)r7c8-(9=1)r8c7-(1=6)r8c1-(6=2)r8c9-(2=6)r9c9-(6=5)r9c4

and hence r7c45,r9c8<>5, solving the puzzle.
_________________
"Obviousness is always the enemy to correctness."-Bertrand Russell
Back to top
View user's profile Send private message
Para
Yokozuna
Yokozuna


Joined: 08 Nov 2006
Posts: 384
Location: The Netherlands

PostPosted: Fri Aug 24, 2007 10:24 am    Post subject: Reply with quote

Hi

The basic thing about xy-wings and xyz-wings and even ALS-xz eliminations is that the digit you try to eliminate has to see all instances of this digit present in the wing/pattern. For an xy-wing the digit you try to eliminate is only present in 2 wing cells. In an xyz-wing that digit is present in all three cells.

greetings

Para
Back to top
View user's profile Send private message
JLynn
Hooked
Hooked


Joined: 25 Jan 2007
Posts: 52
Location: Alaska

PostPosted: Fri Aug 24, 2007 6:57 pm    Post subject: Reply with quote

Thanks for the kind and informative words. Makes a bit more sense now.

Funny you should mention the XY-chain (something else I've yet to tackle...need more patience), rep'nA. SudoCue used a Sashimi Swordfish and then an XY-Chain before the puzzle went to singles.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    SudoCue Users Forum Index -> Help Me! I'm stuck! 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