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		ZeroAssoluto
 
 
  Joined: 05 Feb 2017 Posts: 1020 Location: Rimini, Italy
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				 Posted: Thu Oct 14, 2021 9:21 am    Post subject: Oct 14 VH | 
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				Hi everyone, 
 
 
 	  | Code: | 	 		  
 
+------------+-------------+----------+
 
| 7  5   9   | 26  36  236 | 48 1  48 |
 
| 1  8   3   | 7   9   4   | 6  5  2  |
 
| 6  2   4   | 5   8   1   | 9  7  3  |
 
+------------+-------------+----------+
 
| 5  49  18  | 269 136 236 | 23 48 7  |
 
| 3  6   2   | 4   7   8   | 5  9  1  |
 
| 89 479 178 | 29  135 235 | 23 48 6  |
 
+------------+-------------+----------+
 
| 4  3   78  | 1   2   9   | 78 6  5  |
 
| 2  1   5   | 8   46  67  | 47 3  9  |
 
| 89 79  6   | 3   45  57  | 1  2  48 |
 
+------------+-------------+----------+
 
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Play this puzzle online at the Daily Sudoku site
 
 
 	  | Quote: | 	 		  XY-Wing 4,8,9 in r4c28,r6c1 and -8 in r4c3,r6c8
 
or
 
XY-Wing 4,8,9 in r4c2,r6c18 and -4 in r4c8,r6c2 | 	  
 
 
Ciao Gianni | 
			 
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		TomC
 
 
  Joined: 30 Oct 2020 Posts: 359 Location: Wales
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				 Posted: Thu Oct 14, 2021 10:51 am    Post subject:  | 
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				One of the XY wings solved it for me.
 
 
On reflection, I noticed a conflict in row 4
 
 
In r4c4 you have 269, if it is a 2 or 6 this would give r4c3=1 and in that case the puzzle would be invalid.
 
 
So r4c4 = 9 | 
			 
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		ZeroAssoluto
 
 
  Joined: 05 Feb 2017 Posts: 1020 Location: Rimini, Italy
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				 Posted: Thu Oct 14, 2021 12:25 pm    Post subject:  | 
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				| Which XY-Wing is not working? | 
			 
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		TomC
 
 
  Joined: 30 Oct 2020 Posts: 359 Location: Wales
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				 Posted: Thu Oct 14, 2021 12:46 pm    Post subject:  | 
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				Gianni,
 
Both your XY wings produce a solution, if I find one which solves the puzzle I rarely look for a different one.
 
 
I offer a different view to produce a solution.
 
 
Tom | 
			 
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		ZeroAssoluto
 
 
  Joined: 05 Feb 2017 Posts: 1020 Location: Rimini, Italy
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				 Posted: Thu Oct 14, 2021 12:57 pm    Post subject:  | 
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				| 👌 | 
			 
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		Mogulmeister
 
 
  Joined: 03 May 2007 Posts: 1151
 
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				 Posted: Fri Oct 15, 2021 8:46 am    Post subject:  | 
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				 	  | TomC wrote: | 	 		  One of the XY wings solved it for me.
 
 
On reflection, I noticed a conflict in row 4
 
 
In r4c4 you have 269, if it is a 2 or 6 this would give r4c3=1 and in that case the puzzle would be invalid.
 
 
So r4c4 = 9 | 	  
 
 
Nice one Tom - I think I understand but of course r4c3 does equal 1 doesn't it ? | 
			 
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		TomC
 
 
  Joined: 30 Oct 2020 Posts: 359 Location: Wales
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				 Posted: Fri Oct 15, 2021 9:37 am    Post subject:  | 
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				This was hard for me to describe, I'll try again
 
 
If r4c4 is either 2 or 6 then r6c4=9, r6c1=8, r4c3=1
 
this would then give row 4 to be 
 
 
either
 
| 5 49 1 | 2 36 36 | 2 48 7 |  (two 2's in row4)
 
 
or
 
| 5 49 1 | 6   3    2  | 3 48 7 |  (two 3's in row4)
 
 
so r4c4 must be 9
 
 
also r4c3 is 1 but not if r4c4 is 2 or 6
 
 
Describing this is harder than how I saw this in the first place! | 
			 
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		Mogulmeister
 
 
  Joined: 03 May 2007 Posts: 1151
 
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				 Posted: Fri Oct 15, 2021 10:02 am    Post subject:  | 
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				 	  | TomC wrote: | 	 		  
 
 
Describing this is harder than how I saw this in the first place! | 	  
 
 
Yes - a common problem for us all !    | 
			 
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		Mogulmeister
 
 
  Joined: 03 May 2007 Posts: 1151
 
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				 Posted: Fri Oct 15, 2021 10:40 am    Post subject:  | 
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				 	  | Mogulmeister wrote: | 	 		  I showed the two sides of the ANP in this way to mirror the analysis of something that takes seconds by inspection but far longer to write down !
 
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From a while back….. | 
			 
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