| View previous topic :: View next topic |
| Author |
Message |
Clement
Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania
|
 Posted: Sat Feb 04, 2012 11:39 pm Post subject: Feb 5 VH |
 |
|
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 |
|
 |
hughwill
Joined: 05 Apr 2010
Posts: 424
Location: Birmingham UK
|
| Posted: Sun Feb 05, 2012 10:31 am Post subject: |
|
|
| 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 |
|
|
kuskey
Joined: 10 Dec 2008
Posts: 141
Location: Pembroke, NH
|
| Posted: Sun Feb 05, 2012 4:59 pm Post subject: Feb 5 VH |
|
|
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 |
|
|
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Sun Feb 05, 2012 5:13 pm Post subject: |
|
|
| 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 |
|
|
Clement
Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania
|
| Posted: Mon Feb 06, 2012 8:52 am Post subject: Feb 5 VH |
|
|
| 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 |
|
|
|
|
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
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
