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		| daj95376 
 
 
 Joined: 23 Aug 2008
 Posts: 3854
 
 
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				|  Posted: Tue Apr 12, 2011 12:24 am    Post subject: Puzzle 11/04/11: ~ Difficult |   |  
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				|  	  | Code: |  	  | +-----------------------+ | . 4 . | . 3 . | . 9 2 |
 | 5 3 . | . 9 . | 7 . 8 |
 | . . 9 | . 8 . | 3 . 1 |
 |-------+-------+-------|
 | . . . | . . . | . . 4 |
 | 1 5 4 | . . . | 2 . 9 |
 | . . . | . . 4 | 1 . . |
 |-------+-------+-------|
 | . 2 5 | . 4 3 | . 1 . |
 | 4 . . | . . . | 9 2 5 |
 | 9 1 6 | 8 5 . | . 3 . |
 +-----------------------+
 
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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: Tue Apr 12, 2011 3:25 am    Post subject: |   |  
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				|  	  | Code: |  	  | (6)r4c2=(6)r3c2-(6=2)r3c1-(2=1)r2c3-(1=6)r2c6-r1c46=(6)r1c7; r4c7<>6
 \                                  /
 -(6)r1c1
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 Ted
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		| storm_norm 
 
 
 Joined: 18 Oct 2007
 Posts: 1741
 
 
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				|  Posted: Tue Apr 12, 2011 4:43 am    Post subject: |   |  
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				|  	  | tlanglet wrote: |  	  |  	  | Code: |  	  | (6)r4c2=(6)r3c2-(6=2)r3c1-(2=1)r2c3-(1=6)r2c6-r1c46=(6)r1c7; r4c7<>6
 \                                  /
 -(6)r1c1
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 Ted
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 not to nit pick.  but this part of your structure
 
 (6=2)r3c1-(2=1)r2c3-(1=6)r2c6
 
 is an xy-chain that adds to your eliminations.
 it removes the 6 in r3c6
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		| peterj 
 
 
 Joined: 26 Mar 2010
 Posts: 974
 Location: London, UK
 
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				|  Posted: Tue Apr 12, 2011 8:12 am    Post subject: |   |  
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				| I initially played a skyscraper and then an xy-chain, but also found this one-stepper making the same elimination as Ted's .. 
  	  | Code: |  	  | (6=5)r1c7 - r3c8=(5-7)r3c6=r3c2 - (7=6)r4c2 ; r4c7<>6 | 
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		| tlanglet 
 
 
 Joined: 17 Oct 2007
 Posts: 2468
 Location: Northern California Foothills
 
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				|  Posted: Tue Apr 12, 2011 12:14 pm    Post subject: |   |  
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				|  	  | storm_norm wrote: |  	  |  	  | tlanglet wrote: |  	  |  	  | Code: |  	  | (6)r4c2=(6)r3c2-(6=2)r3c1-(2=1)r2c3-(1=6)r2c6-r1c46=(6)r1c7; r4c7<>6
 \                                  /
 -(6)r1c1
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 Ted
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 not to nit pick.  but this part of your structure
 
 (6=2)r3c1-(2=1)r2c3-(1=6)r2c6
 
 is an xy-chain that adds to your eliminations.
 it removes the 6 in r3c6
 | 
 Norm, Thanks for the comment.  Actually, I initially spotted the xy-wing and while checking for additional deletions by transporting the pincers, I noted the full step. However, I was not sure how to notate the xy-wing deletion so I left it out.
 
 Ted
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		| daj95376 
 
 
 Joined: 23 Aug 2008
 Posts: 3854
 
 
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				|  Posted: Tue Apr 12, 2011 1:21 pm    Post subject: |   |  
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				|  	  | tlanglet wrote: |  	  | Norm, Thanks for the comment.  Actually, I initially spotted the xy-wing and while checking for additional deletions by transporting the pincers, I noted the full step. However, I was not sure how to notate the xy-wing deletion so I left it out. 
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 Suggestion:
 
 ...; r4c6<>6, r3c6<>6 (internal XY-Wing)
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		| tlanglet 
 
 
 Joined: 17 Oct 2007
 Posts: 2468
 Location: Northern California Foothills
 
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				|  Posted: Tue Apr 12, 2011 1:35 pm    Post subject: |   |  
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				|  	  | daj95376 wrote: |  	  |  	  | tlanglet wrote: |  	  | Norm, Thanks for the comment.  Actually, I initially spotted the xy-wing and while checking for additional deletions by transporting the pincers, I noted the full step. However, I was not sure how to notate the xy-wing deletion so I left it out. 
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 Suggestion:
 
 ...; r4c6<>6, r3c6<>6 (internal XY-Wing)
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 Danny, very nice suggestion.
 
 Ted
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		| Asellus 
 
 
 Joined: 05 Jun 2007
 Posts: 865
 Location: Sonoma County, CA, USA
 
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				|  Posted: Tue Apr 12, 2011 6:48 pm    Post subject: |   |  
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				| It can be boiled down rather elegantly to: XYWing[(6)r2c6=(6)r3c1] - Skyscraper[(6)r3c2=(6)r1c7]; r1c146|r2c8|r3c68<>6
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		| Marty R. 
 
 
 Joined: 12 Feb 2006
 Posts: 5770
 Location: Rochester, NY, USA
 
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				|  Posted: Wed Apr 13, 2011 1:00 am    Post subject: |   |  
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				| Skyscraper; r1c1, r3c8<>6 XY-Wing (126), flightless with transport of each pincer; r4c7<>6
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