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Clement
Joined: 24 Apr 2006
Posts: 1110
Location: Dar es Salaam Tanzania
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 Posted: Wed Nov 25, 2009 10:59 pm Post subject: Nov 26 VH |
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Clustered in the begining.
After basic reductions:triples and pairs an XY-Wing-<57>-<78>-<58> is revealed eliminating 5 in r4c8 solving the puzzle in one step. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Nov 26, 2009 5:49 am Post subject: |
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There were a couple of XY-Wings that I saw. For those who enjoy alternatives:
| Code: |
+---------+--------+------------+
| 59 2 6 | 7 39 8 | 135 4 15 |
| 3 7 4 | 1 2 5 | 6 9 8 |
| 59 1 8 | 4 39 6 | 357 2 57 |
+---------+--------+------------+
| 2 9 1 | 6 8 4 | 57 57 3 |
| 6 4 3 | 2 5 7 | 18 18 9 |
| 8 5 7 | 9 1 3 | 2 6 4 |
+---------+--------+------------+
| 47 68 9 | 5 46 1 | 78 3 2 |
| 1 68 2 | 3 7 9 | 4 58 56 |
| 47 3 5 | 8 46 2 | 9 17 167 |
+---------+--------+------------+
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Play this puzzle online at the Daily Sudoku site
There is a potential DP 59-39-35 in boxes 123. R1c7 must be = 1 or r3c7 must = 7 to break the pattern. If r1c7 =1, then r9c8 =7 and this and r3c7 act as pincers 7, removing the 7 from r7c7. |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Thu Nov 26, 2009 2:16 pm Post subject: |
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| I ended up with a bug+1 putting a 7 in r9c9. |
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roaa
Joined: 18 Apr 2009
Posts: 112
Location: Sweden
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| Posted: Thu Nov 26, 2009 3:14 pm Post subject: |
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| There are actually two xy-wings 578. The other eliminates 7 in r4c7. |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Thu Nov 26, 2009 4:06 pm Post subject: |
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| Quote: | | For those who enjoy alternatives: |
For that reason - I used an APE (Aligned Pair Exclusion) in R89C8. (Hey - if you can't find anything unique - what's the point of posting!) |
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Roger S
Joined: 20 Jun 2009
Posts: 6
Location: UK
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| Posted: Thu Nov 26, 2009 7:59 pm Post subject: Nov 26 VH |
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Could you confirm if <17> <78><18> is a valid XY Wing eliminating the 8 in R5 C7.
Just trying to learn how to recognise them
Thanks
Roger |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Nov 26, 2009 8:09 pm Post subject: |
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| Yes Roger, that is a valid XY-Wing. It also eliminates the 8 from r8c8, although that would get eliminated based on the elimination you mentioned. It's just that it's a good idea to look for all possible eliminations. |
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Roger S
Joined: 20 Jun 2009
Posts: 6
Location: UK
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| Posted: Thu Nov 26, 2009 8:50 pm Post subject: |
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| Thanks Marty Understood |
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