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May 27 VH

 
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ZeroAssoluto



Joined: 05 Feb 2017
Posts: 868
Location: Rimini, Italy

PostPosted: Fri May 26, 2017 10:38 pm    Post subject: May 27 VH Reply with quote

Hi everyone,

Code:

+-------------+--------------+-------------+
| 9  5   28   | 1    3   6   | 7   28  4   |
| 4  27  1    | 2578 257 9   | 6   3   28  |
| 6  237 2378 | 278  247 48  | 1   5   9   |
+-------------+--------------+-------------+
| 3  279 6    | 2589 1   58  | 259 4   78  |
| 1  8   29   | 4    259 7   | 3   6   25  |
| 5  4   279  | 2389 6   38  | 29  78  1   |
+-------------+--------------+-------------+
| 8  6   5    | 79   79  2   | 4   1   3   |
| 27 1   39   | 6    45  345 | 8   279 257 |
| 27 39  4    | 35   8   1   | 25  279 6   |
+-------------+--------------+-------------+

Play this puzzle online at the Daily Sudoku site

XY-Wing 2,7,8 in r2c29, r4c9 and -7 in r4c2.

Ciao Gianni
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George Woods



Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK

PostPosted: Sat May 27, 2017 10:47 am    Post subject: Almost an XY wing Reply with quote

The pivot at r6c8 denies a 2 to r1c3 either via r1c8 or the pair of 29 at r56c3 so it is a kind of xy wing according to its mechanics but not apure XY I wonder what it is called a compound XY wing?

Last edited by George Woods on Sat May 27, 2017 1:18 pm; edited 1 time in total
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JC Van Hay



Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium

PostPosted: Sat May 27, 2017 11:43 am    Post subject: Reply with quote

Like the XY-Wing, this is an ALS-XZ Rule.
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Sat May 27, 2017 12:19 pm    Post subject: Re: Almost an XY wing Reply with quote

George Woods wrote:
The pivot at r6c8 denies a 2 to r1c3 either via r1c7 or the pair of 29 at r46c3 so it is a kind of xy wing according to its mechanics but not apure XY I wonder what it is called a compound XY wing?


George, could you enlighten me? I don't see the 29 pair or anything in r1c7?

Quote:

Like the XY-Wing, this is an ALS-XZ Rule.


JC, what is your X and Z value and what cells are being used?
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George Woods



Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK

PostPosted: Sat May 27, 2017 1:13 pm    Post subject: Reply with quote

Sorry I got it wrong I meant r1c8 not r1c7 for one wing that becomes 2 if r6c8 is 8 whilst if r6c8 is 7 then r6c3 becomes 29 so that is equivalen to a wing being 2 since it denies a 2 o r1c3
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JC Van Hay



Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium

PostPosted: Sat May 27, 2017 1:45 pm    Post subject: Re: Almost an XY wing Reply with quote

Marty R. wrote:
JC, what is your X and Z value and what cells are being used?
Code:
+----------------+----------------+----------------+
| 9   5    8-2   | 1     3    6   | 7    (28)  4   |
| 4   27   1     | 2578  257  9   | 6    3     28  |
| 6   237  2378  | 278   247  48  | 1    5     9   |
+----------------+----------------+----------------+
| 3   279  6     | 2589  1    58  | 259  4     78  |
| 1   8    (29)  | 4     259  7   | 3    6     25  |
| 5   4    (279) | 2389  6    38  | 29   (78)  1   |
+----------------+----------------+----------------+
| 8   6    5     | 79    79   2   | 4    1     3   |
| 27  1    39    | 6     45   345 | 8    279   257 |
| 27  39   4     | 35    8    1   | 25   279   6   |
+----------------+----------------+----------------+
ALS-XZ Rule : [(2=8=7)r16c8-(7=92)r65c3]-2r1c3
Note : X=7, Z=2 in the ALS (278)r16c8 and (279)r56c3
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Sat May 27, 2017 3:37 pm    Post subject: Reply with quote

Quote:
I wonder what it is called a compound XY wing?


George, it looks to me like a Forcing Chain with each number in a bivalue cell (r6c8) producing the same outcome.
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Sat May 27, 2017 3:42 pm    Post subject: Reply with quote

Quote:
ALS-XZ Rule : [(2=8=7)r16c8-(7=92)r65c3]-2r1c3
Note : X=7, Z=2 in the ALS (278)r16c8 and (279)r56c3


Nice, JC. I've used the ALS-XZ rule about a half-dozen times, but can no longer find them.
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