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 

Puzzle 11/06/30: ~ XY

 
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: 3855

PostPosted: Thu Jun 30, 2011 4:08 pm    Post subject: Puzzle 11/06/30: ~ XY Reply with quote

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

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: 2461
Location: Northern California Foothills

PostPosted: Fri Jul 01, 2011 3:01 pm    Post subject: Reply with quote

I worked hard on this puzzle and found a couple of weird, messy steps that did not do any significant damage before I found a reasonably clean back breaker...........

almost xy-chain with r2c4(89=3); r78c8<>8
If r2c4=89: (8)r8c7=(8)r2c7-(8=9)r2c4-r5c4=r6c5-(9=8)r6c8;
If r2c4=(3): (3)r2c4-r7c4=r8c5-(3=8)r8c7;

xy-wing (35-8) vertex r3c4; r2c4,r9c6<>8

I would appreciate any suggestion how to combine the two statements for the almost xy-chain.

Ted
Back to top
View user's profile Send private message
daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Fri Jul 01, 2011 3:18 pm    Post subject: Reply with quote

Ted,

Performing a Kraken Cell on r2c4 is a common alternative for your scenario. All you need to do is split your chain at r2c4:

Code:
Kraken Cell r2c4:

read l-to-r:                           ( =9)r2c4-r5c4=r6c5-(9=8)r6c8 -(8)r78c8
read r-to-l: (8)r78c8- (8)r8c7=(8)r2c7-(8= )r2c4
read l-to-r:                           (  3)r2c4-r7c4=r8c5-(3=8)r8c7 -(8)r78c8

You can also perform a 2-String Kite for r2c4<>3, and then use your chain -- which doesn't appear to be an XY-Chain pattern.

Regards, Danny
Back to top
View user's profile Send private message
Luke451



Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California

PostPosted: Fri Jul 01, 2011 9:18 pm    Post subject: Reply with quote

tlanglet wrote:
I worked hard on this puzzle and found a couple of weird, messy steps that did not do any significant damage before I found a reasonably clean back breaker...........

almost xy-chain with r2c4(89=3); r78c8<>8
If r2c4=89: (8)r8c7=(8)r2c7-(8=9)r2c4-r5c4=r6c5-(9=8)r6c8;
If r2c4=(3): (3)r2c4-r7c4=r8c5-(3=8)r8c7;

xy-wing (35-8) vertex r3c4; r2c4,r9c6<>8

I would appreciate any suggestion how to combine the two statements for the almost xy-chain.

Ted

*Maybe* this'll do it, avoid a net and keep your xy.

(8=3)r8c7-r8c5=r7c4-(3)r2c4=[xy chain that I'm too lazy to notate but lives in the * cells]

Code:
*-----------------------------------------------------------*
 | 589   3     89    | 1589  149   458   | 2     7     6     |
 | 689   7     1     |*389   369   2     |*38    5     4     |
 | 568   2     4     | 358   36    7     | 1     389   89    |
 |-------------------+-------------------+-------------------|
 | 189   68    689   | 4     5     3     | 7     2     189   |
 | 79    5     2     |*79    8     1     | 4     6     3     |
 | 1789  4     3     | 2    *79    6     | 5    *89    189   |
 |-------------------+-------------------+-------------------|
 | 4     18    7     | 138   2     9     | 6     138   5     |
 | 2     9     58    | 6     134   458   |*38    138   7     |
 | 3     168   568   | 1578  17    58    | 9     4     2     |
 *-----------------------------------------------------------*
Back to top
View user's profile Send private message
ronk



Joined: 07 May 2006
Posts: 397

PostPosted: Fri Jul 01, 2011 9:49 pm    Post subject: Reply with quote

tlanglet wrote:
almost xy-chain with r2c4(89=3); r78c8<>8
If r2c4=89: (8)r8c7=(8)r2c7-(8=9)r2c4-r5c4=r6c5-(9=8)r6c8;
If r2c4=(3): (3)r2c4-r7c4=r8c5-(3=8)r8c7;
...
I would appreciate any suggestion how to combine the two statements for the almost xy-chain.

I see no clever way to convert the net to a chain. I suppose this does you no good but, in modernized nice-loop notation, it would look like this:

r78c8 -8- r8c7 =8= r2c7 -8- r2c4 {-3- r7c4 =3= r8c5 -3- r8c7 -8- r78c8} -9- r5c4 =9= r6c5 -9- r6c8 -8- r78c8 ==> r78c8<>8
Back to top
View user's profile Send private message
dejsmith



Joined: 23 Oct 2005
Posts: 42

PostPosted: Fri Jul 01, 2011 10:23 pm    Post subject: Reply with quote

How come you cannot use the Kite in r7/c7 to eliminate the 3 in r2c4? Then why isn't that an XY Chain, starting at r8c7: 83-38-89-97-79-98; & r78c8<>8?

I tried something different using a UR & 2 kites, but did not see the XY Chain. Instead I tried looking for an almost pattern & chose an ANP in r4c3; 89-6. 6 led to a contradiction & 89 solved the puzzle. Was I just lucky & do I have an incorrect understanding of these techniques?

Dave
Back to top
View user's profile Send private message
Marty R.



Joined: 12 Feb 2006
Posts: 5166
Location: Rochester, NY, USA

PostPosted: Sat Jul 02, 2011 4:52 am    Post subject: Reply with quote

Finned X-Wing; r2c4<>3
W-Wing (89), SL 9, c5, flightless with transport; r2c7, r3c4<>8
XY-Wing (385); r1c6, r9c4<>5
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