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 

10 Aug VH

 
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Daily Sudoku puzzles
View previous topic :: View next topic  
Author Message
cgordon



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

PostPosted: Fri Aug 10, 2007 1:58 pm    Post subject: 10 Aug VH Reply with quote

Can I be first. I needed an xy wing with a 43 pivot on R5C6 (which gets rid of 9 in R3C9. Then a skyscraper on 9s in Cols 6 & 7. (gets rid of 9 in R3C8). Not sure that step was necessary.
Back to top
View user's profile Send private message
sdq_pete



Joined: 30 Apr 2007
Posts: 119
Location: Rotterdam, NL

PostPosted: Fri Aug 10, 2007 3:30 pm    Post subject: Reply with quote

I can't quite relate that to the position I reached, which was the following:
Code:

+---------+----------+------------+
| 2  5 6  | 4  19 7  | 19  3   8  |
| 3  9 48 | 18 2  6  | 14  7   5  |
| 1  7 48 | 38 5  39 | 2   469 46 |
+---------+----------+------------+
| 4  8 9  | 2  36 5  | 36  1   7  |
| 5  6 1  | 7  8  34 | 34  2   9  |
| 7  2 3  | 9  46 1  | 8   5   46 |
+---------+----------+------------+
| 69 3 2  | 5  7  49 | 469 8   1  |
| 8  1 7  | 6  49 2  | 5   49  3  |
| 69 4 5  | 13 13 8  | 7   69  2  |
+---------+----------+------------+

Play this puzzle online at the Daily Sudoku site

I unlocked this position with a slightly unorthodox application of an XYZ wing. Note the XYZ-wing with pivot at R3C8 and pincers R3C9 and R8C8. There is no direct victim. However, either one of R3C8 and R3C9 is 4, or R8C8 is 4. Both lead easily to R7C6 = 4 and R8C5 = 9.

Peter
Back to top
View user's profile Send private message Visit poster's website
TKiel



Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI

PostPosted: Fri Aug 10, 2007 4:24 pm    Post subject: Reply with quote

The X-wing on 4 in R57 is a little cleaner.
Back to top
View user's profile Send private message
cgordon



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

PostPosted: Fri Aug 10, 2007 6:47 pm    Post subject: Reply with quote

Sdq. Pete: I couldn't see how you got the 9 in R5C9.

But anyway, with you "victimless xyz" thing, you still seem to end up with 2 trial and error assumptions. In this case I think it was a coincidence that they both worked.
Back to top
View user's profile Send private message
Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Sat Aug 11, 2007 4:33 am    Post subject: Reply with quote

I used the 34-39-49 XY-Wing to zap the 9 in r3c9, creating a strong link on 9 in row 3. That allowed a W-Wing on the 49s in r7c6 and r8c8, which solved r8c5=9, which finished the puzzle.

Code:

+---------+----------+------------+
| 2  5 6  | 4  19 7  | 19  3   8  |
| 3  9 48 | 18 2  6  | 14  7   5  |
| 1  7 48 | 38 5  39 | 2   469 46 |
+---------+----------+------------+
| 4  8 9  | 2  36 5  | 136 16  7  |
| 5  6 1  | 7  8  34 | 349 2   49 |
| 7  2 3  | 9  46 1  | 8   5   46 |
+---------+----------+------------+
| 69 3 2  | 5  7  49 | 469 8   1  |
| 8  1 7  | 6  49 2  | 5   49  3  |
| 69 4 5  | 13 13 8  | 7   69  2  |
+---------+----------+------------+

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



Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI

PostPosted: Sat Aug 11, 2007 2:07 pm    Post subject: Reply with quote

From the position Marty posted, it's also possible to exclude <9> from three of the four tri-value cells (Marty's XY-wing does one), which turns it into a BUG+1.
Back to top
View user's profile Send private message
keith



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

PostPosted: Sat Aug 11, 2007 3:26 pm    Post subject: Reply with quote

TKiel wrote:
The X-wing on 4 in R57 is a little cleaner.


In Marty's grid there is a swordfish in C589 which takes out <4> in R3C3, essentially the same elimination as the X-wing.

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



Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium

PostPosted: Sat Aug 11, 2007 10:43 pm    Post subject: Reply with quote

There was also a diffirent solution path, which I took after the xy-wing pivot in R5C6, that cgordon mentioned. I don't now why but I spot these xy-chains sometimes easier than an xy-wing. This one was an 9cell xy-chain, which eliminates <4> in R3C8, because of the pincer-effect from the two <4>'s in R3C9 and R3C3.

[46][64][46][63][34][49][93][38][84]

Code:

+---------+----------+------------+
| 2  5 6  | 4  19 7  | 19  3   8  |
| 3  9 48 | 18 2  6  | 14  7   5  |
| 1  7 I48|H38 5  G39| 2  -469 A46|
+---------+----------+------------+
| 4  8 9  | 2  D36 5 | 36  1   7  |
| 5  6 1  | 7  8  E34| 34  2   9  |
| 7  2 3  | 9  C46 1 | 8   5   B46|
+---------+----------+------------+
| 69 3 2  | 5  7  F49| 469 8   1  |
| 8  1 7  | 6  49 2  | 5   49  3  |
| 69 4 5  | 13 13 8  | 7   69  2  |
+---------+----------+------------+
Back to top
View user's profile Send private message Send e-mail
Earl



Joined: 30 May 2007
Posts: 677
Location: Victoria, KS

PostPosted: Mon Aug 13, 2007 10:42 pm    Post subject: August 13 VH Reply with quote

I found a number of hidden pairs and triplets, a few x-wings, and then the decisive move was an xy-wing anchored in R9C1 which made R3C4 a 9.

Earl
Back to top
View user's profile Send private message Send e-mail
eddieg



Joined: 12 Jan 2006
Posts: 47
Location: San Diego, CA USA

PostPosted: Wed Aug 15, 2007 3:21 pm    Post subject: Now I get it. Reply with quote

Marty, Thanks for clarification on the XY-Wing that helped to eliminate the 9 in R3C9. I had a real obstacle to making the link (for some unkonwn) reason. My sanity is restored.
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Daily Sudoku 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