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Vanhegan extreme

 
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Marty R.



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

PostPosted: Wed Feb 22, 2012 4:22 pm    Post subject: Vanhegan extreme Reply with quote

Puzzle 6-633429, rated 1.3.0.1.1

Played one Finned X-Wing but hit the brick wall.

Code:

+----------------+---------------+---------------+
| 3    57   159  | 589  589  6   | 179  4     2  |
| 4    6    1259 | 2359 7    135 | 139  1359  8  |
| 125  257  8    | 4    259  135 | 6    13579 35 |
+----------------+---------------+---------------+
| 7    248  24   | 38   1    348 | 5    6     9  |
| 59   1    6    | 7    59   2   | 34   8     34 |
| 589  458  3    | 589  6    458 | 27   27    1  |
+----------------+---------------+---------------+
| 125  3    7    | 6    245  9   | 8    125   45 |
| 1258 2458 1245 | 25   3    7   | 1249 1259  6  |
| 6    9    245  | 1    2458 58  | 234  235   7  |
+----------------+---------------+---------------+

Play this puzzle online at the Daily Sudoku site
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JC Van Hay



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

PostPosted: Wed Feb 22, 2012 6:28 pm    Post subject: Reply with quote

From a B/B-Plot POV, the first weakest points in the brick wall to look at are the cells r2c4, r1c7 and r3c8.

"Fortunately", they enter into an AIC (involving only bilocals) as follows :

Code:
+--------------------+----------------------+--------------------+
| 3     57    5(19)  | 589      589     6   | 9(17)  4        2  |
| 4     6     15(29) | 35-9(2)  7       135 | 139    1359     8  |
| 125   257   8      | 4        5-2(9)  135 | 6      135(79)  35 |
+--------------------+----------------------+--------------------+
| 7     248   24     | 38       1       348 | 5      6        9  |
| 59    1     6      | 7        59      2   | 34     8        34 |
| 589   458   3      | 589      6       458 | 27     27       1  |
+--------------------+----------------------+--------------------+
| 125   3     7      | 6        245     9   | 8      125      45 |
| 1258  2458  1245   | 25       3       7   | 1249   1259     6  |
| 6     9     245    | 1        2458    58  | 234    235      7  |
+--------------------+----------------------+--------------------+

5-SIS AIC : 2r2c4=(2-9)r2c3=(9-1)r1c3=(1-7)r1c7=(7-9)r3c8=9r3c5 => -9r2c4, -2r3c5; stte
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

PostPosted: Wed Feb 22, 2012 8:17 pm    Post subject: Reply with quote

JC Van Hay wrote:


Code:
+--------------------+----------------------+--------------------+
| 3     57    5(19)  | 589      589     6   | 9(17)  4        2  |
| 4     6     15(29) | 35-9(2)  7       135 | 139    1359     8  |
| 125   257   8      | 4        5-2(9)  135 | 6      135(79)  35 |
+--------------------+----------------------+--------------------+
| 7     248   24     | 38       1       348 | 5      6        9  |
| 59    1     6      | 7        59      2   | 34     8        34 |
| 589   458   3      | 589      6       458 | 27     27       1  |
+--------------------+----------------------+--------------------+
| 125   3     7      | 6        245     9   | 8      125      45 |
| 1258  2458  1245   | 25       3       7   | 1249   1259     6  |
| 6     9     245    | 1        2458    58  | 234    235      7  |
+--------------------+----------------------+--------------------+

5-SIS AIC : 2r2c4=(2-9)r2c3=(9-1)r1c3=(1-7)r1c7=(7-9)r3c8=9r3c5 => -9r2c4, -2r3c5; stte


My favorite pattern is there also: there is a strong link in 2 from r2c4 to both r2c3 and r3c5 which are connected as you show. The result is r2c4 has to be a 2.

2r2c4=(2-9)r2c3=(9-1)r1c3=(1-7)r1c7=(7-9)r3c8=(9-2)r3c5=2r2c4 => r2c4=2
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Marty R.



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

PostPosted: Wed Feb 22, 2012 10:34 pm    Post subject: Reply with quote

Thanks JC and Dan for the responses, which I unfortunately don't understand.

I don't know what "B/B-plot" and "bilocals" mean and can't follow the AIC chain.

Dan, can you spot that pattern and know what cell must=2 or do you have to do some testing after you spot it? Does the pattern have a name?

Embarassed Question Crying or Very sad Embarassed
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

PostPosted: Wed Feb 22, 2012 11:20 pm    Post subject: Reply with quote

Marty R. wrote:
Dan, can you spot that pattern and know what cell must=2 or do you have to do some testing after you spot it? Does the pattern have a name?


I look for a cell with a candidate with two strong links. Then I try to connect the linked cells with a chain. If I can the cell with two strong links can be set to the candidate.

if the start of the chain = 2 and the end of the chain = 2 and both are the same cell then it must = 2.

I have to admit I missed this one. I spotted it in JC's solution.

It is called a Discontinuous loop or a turbot fish if the chain contains 5 cells.

hope this helps

dan
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Wed Feb 22, 2012 11:43 pm    Post subject: Reply with quote

Code:
(2)r2c4=(2-9)r2c3=(9-1)r1c3=(1-7)r1c7=(7-9)r3c8=(9-2)r3c5=(2)r2c4 => r2c4=2

Dan's chain as a sequence of overlapping strong links:

Code:
r2c4<>2 -> r2c3=3
           r2c3<>9 -> r1c3=9
                      r1c3<>1 -> r1c7=1
                                 r1c7<>7 -> r3c8=7
                                            r3c8<>9 -> r3c5=9
                                                       r3c5<>2 -> r2c4=2
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JC Van Hay



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

PostPosted: Fri Feb 24, 2012 7:57 am    Post subject: Reply with quote

Marty R. wrote:
I don't know what "B/B-plot" and "bilocals" mean and can't follow the AIC chain.

Marty, Sudopedia is now accessible again. Look for the definitions and eventually for more informations from here.

Best regards, JC.
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