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Vanhegan extreme, part deux

 
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Wed Nov 24, 2010 10:03 pm    Post subject: Vanhegan extreme, part deux Reply with quote
This is puzzle 6-1555638, rated 2.2.0.0.1, supposedly easier than the one I posted earlier. I've made -0- moves.

Code:

+-----------------+----------+--------------+
| 8     6    35   | 35 7  4  | 1   2   9    |
| 157   137  4    | 9  2  13 | 57  8   6    |
| 12579 1279 159  | 56 8  16 | 4   357 37   |
+-----------------+----------+--------------+
| 127   1237 8    | 4  6  9  | 27  137 5    |
| 12579 4    1359 | 8  13 25 | 279 6   1237 |
| 6     1239 1359 | 7  13 25 | 8   139 4    |
+-----------------+----------+--------------+
| 19    8    7    | 36 4  36 | 259 159 12   |
| 4     19   6    | 2  5  8  | 3   179 17   |
| 3     5    2    | 1  9  7  | 6   4   8    |
+-----------------+----------+--------------+

Play this puzzle online at the Daily Sudoku site
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK
PostPosted: Thu Nov 25, 2010 1:31 pm    Post subject: Reply with quote
Marty, another brute!
However I found a short SIN that opens it up..
Code:
+--------------------+----------+------------------+
| 8       6     35   | 35 7  4  | 1      2   9     |
| 157     137   4    | 9  2  13 | 57     8   6     |
| 12579   1279  159  | 56 8  16 | 4      357 37    |
+--------------------+----------+------------------+
| (1)(27) 123-7 8    | 4  6  9  | (27)   137 5     |
| 125(7)9 4     1359 | 8  13 25 | *27(9) 6   123(7)|
| 6       1239  1359 | 7  13 25 | 8      139 4     |
+--------------------+----------+------------------+
| (19)    8     7    | 36 4  36 | *25(9) 159 12    |
| 4       (19)  6    | 2  5  8  | 3      179 (17)  |
| 3       5     2    | 1  9  7  | 6      4   8     |
+--------------------+----------+------------------+
ANP(27)[(27)r4c17=(1)r4c1] - (1=9)r7c1 - (9=1)r8c2 - (1=7)r8c9 - (7)r5c9=r5c1 ; r4c2<>7
                                       \       (9)r7c7=r5c7    /

The strong link on 9 forces (9)r5c7 which creates the final strong link on 7.

After this its SSTS ...

xy-wing(15-3) r2c1
xy-wing(15-9) r2c1
x-wing(9)
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Thu Nov 25, 2010 4:21 pm    Post subject: Reply with quote
Thanks Peter. What do SIN and SSTS stand for?
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Thu Nov 25, 2010 8:06 pm    Post subject: Reply with quote
As Peter indicated, this is not a friendly puzzle. My solver's solution contained three chains. However, my solver also identified a crazy SIN with secondary effects all over the place. I couldn't resist sharing it. _ Twisted Evil _

Code:
 +-----------------------------------------------------------------------+
 |  8      6      35     |  35     7      4      |  1      2      9      |
 |  157    137    4      |  9      2      13     |  57     8      6      |
 |  12579  1279   159    |  56     8      16     |  4      357    37     |
 |-----------------------+-----------------------+-----------------------|
 |  127    1237   8      |  4      6      9      |  27     137    5      |
 |  12579  4      1359   |  8      13     25     |  279    6      1237   |
 |  6      1239   1359   |  7      13     25     |  8      139    4      |
 |-----------------------+-----------------------+-----------------------|
 |  19     8      7      |  36     4      36     |  259    159    12     |
 |  4      19     6      |  2      5      8      |  3      179    17     |
 |  3      5      2      |  1      9      7      |  6      4      8      |
 +-----------------------------------------------------------------------+
 # 66 eliminations remain

The easiest way to present it is in parts: Part #1

Code:
r5c1=2  =>  r5c1<>5
r5c1=9  =>  r5c1<>5

If r5c1<>2 & r5c1<>9, then strong links are forced in [c1] and the following SIN exists: Part #2

Code:
                         ......................... - (2  )r7c7
                        /                              |
(5=2)r5c6 - r5c79 = r4c7 - r4c1 = (2-9)r3c1 = r7c1 - (9=5)r7c7 - r2c7 = (5)r2c1 ; r5c1<>5
_________________________________________________________________________________________

Unfortunately, that darn X-Wing(9) is still needed in the solution! _ Sad _
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK
PostPosted: Fri Nov 26, 2010 7:43 am    Post subject: Reply with quote
Marty R. wrote:
Thanks Peter. What do SIN and SSTS stand for?

SIN is Single Inference Network - not sure of the exact definition, but I take it to mean a network where there is only a single branch i.e one inference to consider seperate from the chain.
SSTS is Simple Sudoku Technique Set i.e. the rest of the puzzle solves using the basic solver in Simple Sudoku (basics, x-wings, xy-wings and colouring).

Danny, nice one - hard one to spot! I tried for a long time to get around the x-wing trying to construct some sort of kraken move around it - but not luck.
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