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dongrave
Joined: 06 Mar 2014
Posts: 572
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 Posted: Sun Oct 02, 2016 12:14 am Post subject: Yet another one from 1sudoku |
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I couldn't see today's puzzle from this site either. I hope it gets fixed soon. I'm sure that Sam will get right on it - especially seeing how much I've praised him in the past.  Anyway, I decided to do another 'Evil' puzzle from 1sudoku.com instead. I had trouble with it - but finally ended up finding a one-stepper. (I don't think it can be solved using just wings. Correct me if I'm wrong.)
| Code: |
1sudoku.net #528188 Evil
+-------+-------+-------+
| . . 3 | . 5 . | . . 9 |
| . . 4 | . 7 9 | . 1 . |
| . 7 . | 8 . . | . . 4 |
+-------+-------+-------+
| 9 . . | . . . | . 6 . |
| 1 . 5 | . . . | 8 . 2 |
| . 8 . | . . . | . . 7 |
+-------+-------+-------+
| 3 . . | . . 8 | . 5 . |
| . 5 . | 1 4 . | 9 . . |
| 7 . . | . 6 . | 3 . . |
+-------+-------+-------+
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JC Van Hay
Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium
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| Posted: Sun Oct 02, 2016 3:56 am Post subject: |
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| Code: | +-------------+-----------------------+---------------+
| 26 1 3 | 246 5 246 | 7 8 9 |
| 8 26 4 | 236 7 9 | 256 1 35 |
| 5 7 9 | 8 12(3) 126 | 26 2(3) 4 |
+-------------+-----------------------+---------------+
| 9 23 7 | 2345 8 1245 | 145 6 35 |
| 1 36 5 | 3469 9-3 7 | 8 349 2 |
| 4 8 26 | 2569(3) 129(3) 1256 | 15 9(3) 7 |
+-------------+-----------------------+---------------+
| 3 49 16 | 7 29 8 | 24 5 16 |
| 26 5 268 | 1 4 3 | 9 7 68 |
| 7 49 18 | 259 6 25 | 3 24 18 |
+-------------+-----------------------+---------------+
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XWing(3R36)-3r5c5; stte |
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dongrave
Joined: 06 Mar 2014
Posts: 572
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| Posted: Sun Oct 02, 2016 1:14 pm Post subject: |
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| I'm confused JC. That's obviously not a 'pure' X Wing (of which I'm sure you're aware). I see that you even enclosed the 3 in r6c4 in parens but I also see that your logic works. What is this type of X Wing called and how far can one extend this logic? Thanks, Don. |
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Clement
Joined: 24 Apr 2006
Posts: 1113
Location: Dar es Salaam Tanzania
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| Posted: Thu Oct 06, 2016 5:16 pm Post subject: Yet another one from 1sudoku |
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| dongrave wrote: | | I'm confused JC. That's obviously not a 'pure' X Wing (of which I'm sure you're aware). I see that you even enclosed the 3 in r6c4 in parens but I also see that your logic works. What is this type of X Wing called and how far can one extend this logic? Thanks, Don. |
We can call it a skyscraper with grouped node. |
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JC Van Hay
Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium
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| Posted: Thu Oct 06, 2016 7:00 pm Post subject: |
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Don,
Finned XWing but more generally the definition of an XWing should be the following :
XWing : the solutions of the set C of all the candidates of a single digit in 2 units exclude a non-empty set X of candidates.
In a latin square : C is made up of the 4 candidates at the intersection of 2 rows and 2 columns [pure(?) Xwing]
In a sudoku : there are more "patterns" in the 4 boxes at the intersection of 2 rows of boxes and 2 columns of boxes. They are also respectively called XWing and 2-stringed kite as in the following examples with the greatest number of candidates as possible : | Code: | -1 1 1 | 1 1 1 or -1 1 1 | 1 1 1 or -1 1 1 | 1 1 1
-1 1 1 | 1 1 1 -1 1 1 | 1 1 . 1 1 1 | 1 1 .
1 1 1 | 1 . . 1 1 1 | 1 1 . 1 1 1 | 1 1 .
------------- ------------- -------------
1 1 1 | 1 1 1 1 1 1 | 1 1 1 1 1 1 | 1 1 1
1 1 1 | 1 1 1 1 1 . | 1 1 . 1 1 1 | 1 1 1
1 . . | 1 . . 1 1 . | 1 1 . 1 . . | 1 1 .
C=XWing{1R36} C=XWing{1C36} C=Kite{1R6, 1C6}
X={1r12c1} X={1r12c1} X={1r1c1} |
How to find them ? In the 4 boxes in question, just enumerate the solutions from either a bilocal in 2 boxes or from an almost locked candidates.
Notes : with less candidates in the 4 boxes,
1. the number of exclusions can change,
2. a lot of other particular names are given to the XWing but they are of no interest to find the exclusion(s)!
JC |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Oct 08, 2016 9:41 pm Post subject: |
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| Code: |
+-----------+-----------------+------------+
| 26 1 3 | 246 5 246 | 7 8 9 |
| 8 26 4 | 236 7 9 | 256 1 35 |
| 5 7 9 | 8 123 126 | 26 23 4 |
+-----------+-----------------+------------+
| 9 23 7 | 2345 8 1245 | 145 6 35 |
| 1 36 5 | 3469 39 7 | 8 349 2 |
| 4 8 26 | 23569 1239 1256 | 15 39 7 |
+-----------+-----------------+------------+
| 3 49 16 | 7 29 8 | 24 5 16 |
| 26 5 268 | 1 4 3 | 9 7 68 |
| 7 49 18 | 259 6 25 | 3 24 18 |
+-----------+-----------------+------------+
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Play this puzzle online at the Daily Sudoku site
(5=1)r6c7-r6c56=r4c6-(1=263)r3c678-(3=5)r2c9=> -5r4c9 |
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