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 

Feb 5 VH

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



Joined: 24 Apr 2006
Posts: 663
Location: Dar es Salaam Tanzania

PostPosted: Sat Feb 04, 2012 11:39 pm    Post subject: Feb 5 VH Reply with quote

After the Basics
Code:
[code]
+-----------+---------+------------+
| 6  5  1   | 9 4  7  | 8   2   3  |
| 8  7  2   | 1 6  3  | 4   9   5  |
| 4  3  9   | 2 8  5  | 16  17  67 |
+-----------+---------+------------+
| 59 28 358 | 7 19 6  | 15  34  24 |
| 1  6  4   | 3 5  2  | 7   8   9  |
| 7  29 35  | 4 19 8  | 156 13  26 |
+-----------+---------+------------+
| 59 1  6   | 8 3  49 | 2   457 47 |
| 3  4  7   | 5 2  1  | 9   6   8  |
| 2  89 58  | 6 7  49 | 3   45  1  |
+-----------+---------+------------+
[/code]BUG+2
Either r6c7=1 or r7c8=4
By the following chains
If r6c7=1 =>r6c8=3 =>r4c8=4 =>r9c8=5
If r7c8=4 =>r9c8=5. We deduce that r9c8=5 which solves it.
Back to top
View user's profile Send private message AIM Address
hughwill



Joined: 05 Apr 2010
Posts: 171
Location: Birmingham UK

PostPosted: Sun Feb 05, 2012 10:31 am    Post subject: Reply with quote

Code:

+----------+---------+------------+
| 6  5  1  | 9 4  7  | 8   2   3  |
| 8  7  2  | 1 6  3  | 4   9   5  |
| 4  3  9  | 2 8  5  | 16  17  67 |
+----------+---------+------------+
| 59 28 38 | 7 19 6  | 15  34  24 |
| 1  6  4  | 3 5  2  | 7   8   9  |
| 7  29 35 | 4 19 8  | 156 13  26 |
+----------+---------+------------+
| 59 1  6  | 8 3  49 | 2   457 47 |
| 3  4  7  | 5 2  1  | 9   6   8  |
| 2  89 58 | 6 7  49 | 3   45  1  |
+----------+---------+------------+

Play this puzzle online at the Daily Sudoku site

There's a naked triple 159 on r4 to come out in basics. (see grid)
A 135 XY centred on r6c8
also sorts out the puzzle (select text to reveal)
Back to top
View user's profile Send private message
kuskey



Joined: 10 Dec 2008
Posts: 127
Location: Pembroke, NH

PostPosted: Sun Feb 05, 2012 4:59 pm    Post subject: Feb 5 VH Reply with quote

The solution that leaps off the grid is the 135 xy-wing with pivot at r6c8 setting r4c1 and r6c7<>5.

Clement, your basic work is not quite complete--after taking the 159 triple in r4, r4c3<>5. Now if you assume r7c8=4, you force a conflict in 4s at r4c8. IMHO, the correct solution for the BUG+2 is r6c7=1.
Back to top
View user's profile Send private message
Marty R.



Joined: 12 Feb 2006
Posts: 5156
Location: Rochester, NY, USA

PostPosted: Sun Feb 05, 2012 5:13 pm    Post subject: Reply with quote

Quote:
Clement, your basic work is not quite complete--after taking the 159 triple in r4, r4c3<>5. Now if you assume r7c8=4, you force a conflict in 4s at r4c8. IMHO, the correct solution for the BUG+2 is r6c7=1.

I don't know that there's such a thing as a "correct" solution for a BUG+2. Any valid technique that works is correct.

For example, on all BUGs+2 I get greater enjoyment from using pincers. We have the two possibilities of 1 and 4. The 1 proves a 4 in r4c8, which with the 4 in r7c8 sets r9c8<>4.

Or the 4 proves 1 in r6c8, which with the 1 in r6c7 sets r6c5<>1.

There are additional possibilities with pincers as well, such as the 4 proving a 1 in r4c5.

Neither these nor Clement's solution are "incorrect."
Back to top
View user's profile Send private message
Clement



Joined: 24 Apr 2006
Posts: 663
Location: Dar es Salaam Tanzania

PostPosted: Mon Feb 06, 2012 8:52 am    Post subject: Feb 5 VH Reply with quote

kuskey, it depends on which path you take. For example in this puzzle there are 8 cells which come out with the the same solution whether r6c7=1 or r7c8=4. These are the true solutions to those cells, e.g r4c1=9 whatever the choice of the solution in r6c7 and r7c8 as explained above, but, it is a long path. I decided to take a short path.
Back to top
View user's profile Send private message AIM Address
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