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		| daj95376 
 
 
 Joined: 23 Aug 2008
 Posts: 3854
 
 
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				|  Posted: Mon Feb 23, 2009 5:00 pm    Post subject: Set NNP_2 Puzzle 82 |   |  
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				|  	  | Code: |  	  | +-----------------------+ | 5 . 3 | 8 . . | . . . |
 | . 9 . | . . . | . 1 . |
 | 6 . . | 9 . . | 7 . . |
 |-------+-------+-------|
 | 9 . 6 | 1 . . | . . 2 |
 | . . . | . 9 . | . 4 . |
 | . . . | . . 8 | 9 . . |
 |-------+-------+-------|
 | . . 9 | . . 1 | 4 2 . |
 | . 4 . | . 6 . | 3 8 . |
 | . . . | 5 . . | . . 1 |
 +-----------------------+
 
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 Play this puzzle online at the Daily Sudoku site
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		| tlanglet 
 
 
 Joined: 17 Oct 2007
 Posts: 2468
 Location: Northern California Foothills
 
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				|  Posted: Mon Feb 23, 2009 6:04 pm    Post subject: |   |  
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				| Two steps:  	  | Quote: |  	  | Back-to-back x-wings <7>. 
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 Ted
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		| daj95376 
 
 
 Joined: 23 Aug 2008
 Posts: 3854
 
 
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				|  Posted: Mon Feb 23, 2009 7:47 pm    Post subject: |   |  
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				| Ted: I can't duplicate your results. |  | 
	
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		| tlanglet 
 
 
 Joined: 17 Oct 2007
 Posts: 2468
 Location: Northern California Foothills
 
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				|  Posted: Mon Feb 23, 2009 10:28 pm    Post subject: |   |  
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				|  	  | daj95376 wrote: |  	  | Ted: I can't duplicate your results. | 
 
 My Turn
   
 The first x-wing is right after basics. The second x-wing was not valid. I thought it was in r25c36 to delete <7> in r6c9, but col <6> contains another digit <7>.
 
 Sorry ......... I will have to look for another solution.
 
 Ted
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		| storm_norm 
 
 
 Joined: 18 Oct 2007
 Posts: 1741
 
 
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				|  Posted: Tue Feb 24, 2009 5:21 am    Post subject: |   |  
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				| this is the grid after the x-wing on 7 and the skyscraper on 8's 
  	  | Code: |  	  | .------------------.------------------.------------------. | 5     17    3    | 8     17    6    | 2     9     4    |
 |*28    9    *278  | 4    *23    237  | 5     1     6    |
 | 6     12    4    | 9     125   25   | 7     3     8    |
 :------------------+------------------+------------------:
 | 9     37    6    | 1    *37    4    | 8     5     2    |
 | 238   2358 *278  | 6     9    *2357 | 1     4    *37   |
 | 4     235   1    | 27   *235   8    | 9     6     37   |
 :------------------+------------------+------------------:
 | 7     6     9    | 3     8     1    | 4     2     5    |
 | 1     4     5    | 27    6     27   | 3     8     9    |
 | 238   238   28   | 5     4     9    | 6     7     1    |
 '------------------'------------------'------------------'
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 then the result of the 5 and 7 gone from r2c5, leaves 2 and 3 which makes this nice chain.  this chain makes an elimination in one cell and moves on to make another elimination.
 (2=3)r2c5 - (3)r46c5 = (3)r5c6 - (3=7)r5c9 - (7)r5c3 = (7)r2c3; r2c3 <> 2
 (2=3)r2c5 - (3)r46c5 = (3)r5c6 - (3=7)r5c9 - (7)r5c3 = (7-8)r2c3 = (8)r2c1; r2c1 <> 2
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		| tlanglet 
 
 
 Joined: 17 Oct 2007
 Posts: 2468
 Location: Northern California Foothills
 
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				|  Posted: Tue Feb 24, 2009 2:27 pm    Post subject: |   |  
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				| On my second attempt to find a valid solution for this puzzle, I found: 
  	  | Quote: |  	  | my original x-wing <7>, the skyscraper on <8> noted by Norm and a xy-wing <237> with pivot <37> in r4c5 making one deletion on <2> and, after some cleanup,  transporting <2> in pincer r2c5 => r3c5 => r3c2 makes another deletion and completes the puzzle. 
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 Ted
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		| Marty R. 
 
 
 Joined: 12 Feb 2006
 Posts: 5770
 Location: Rochester, NY, USA
 
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				|  Posted: Tue Feb 24, 2009 10:01 pm    Post subject: |   |  
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				| Two ERs did it for me. |  | 
	
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		| storm_norm 
 
 
 Joined: 18 Oct 2007
 Posts: 1741
 
 
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				|  Posted: Tue Feb 24, 2009 11:08 pm    Post subject: |   |  
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				|  	  | Marty R. wrote: |  	  | Two ERs did it for me. | 
 Marty,
 might want to recheck that.
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		| Marty R. 
 
 
 Joined: 12 Feb 2006
 Posts: 5770
 Location: Rochester, NY, USA
 
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				|  Posted: Wed Feb 25, 2009 12:22 am    Post subject: |   |  
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				|  	  | storm_norm wrote: |  	  |  	  | Marty R. wrote: |  	  | Two ERs did it for me. | 
 Marty,
 might want to recheck that.
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 I did as soon as I opened this thread and saw the other responses. After the ERs I needed an XY-Wing and a W-Wing.
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