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Jan 26 2007 VH

 
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dldcamp



Joined: 29 May 2007
Posts: 15
Location: Florida

PostPosted: Sun Jun 03, 2007 12:43 pm    Post subject: Jan 26 2007 VH Reply with quote

Just when we think we're getting it.... Anyway, the next hint is a 7 in r1c6. We can't find the logic...Which doesn't mean much!


Code:

+---------------+------------------+------------------+
| 4   15   579  | 3    8     17    | 6      2    159  |
| 238 1256 3578 | 1257 12567 9     | 1345   345  135  |
| 239 1256 359  | 4    1256  126   | 1359   7    8    |
+---------------+------------------+------------------+
| 6   4    89   | 58   59    3     | 2      1    7    |
| 89  3    1    | 2578 4     278   | 589    6    59   |
| 5   7    2    | 6    19    18    | 389    389  4    |
+---------------+------------------+------------------+
| 1   8    34   | 27   267   5     | 3479   349  369  |
| 23  25   345  | 9    1267  12678 | 134578 3458 1356 |
| 7   9    6    | 18   3     4     | 158    58   2    |
+---------------+------------------+------------------+

Play this puzzle online at the Daily Sudoku site
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Sun Jun 03, 2007 1:12 pm    Post subject: Reply with quote

There is a pair in B5. There is a quad in R2. This will reveal an XY-wing that makes the elimination.

There is much you can do to simplify the candidate lists.

Keith
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dldcamp



Joined: 29 May 2007
Posts: 15
Location: Florida

PostPosted: Sun Jun 03, 2007 6:33 pm    Post subject: Reply with quote

I had already found the pair and quad. But, where is the XY wing? This is new to me and I still haven't found one yet on my own.
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Mon Jun 04, 2007 5:00 am    Post subject: Reply with quote

After you simplify the candidates:
Code:
+-------------------+-------------------+-------------------+
| 4     15    579   | 3     8     17#   | 6     2     159   |
| 28    26    78    | 15@   267   9     | 1345  345   135   |
| 239   1256  359   | 4     1256  126   | 159   7     8     |
+-------------------+-------------------+-------------------+
| 6     4     89    | 58@   59    3     | 2     1     7     |
| 89    3     1     | 27    4     27    | 589   6     59    |
| 5     7     2     | 6     19    18@   | 389   389   4     |
+-------------------+-------------------+-------------------+
| 1     8     34    | 27    267   5     | 3479  349   369   |
| 23    25    345   | 9     167   1678  | 13478 348   136   |
| 7     9     6     | 18    3     4     | 158   58    2     |
+-------------------+-------------------+-------------------+

The XY-wing 15-58-18 (@) eliminates <1> in R1C6 (#).

In my interpretation, an XY-wing is a triple (ab, ac, bc) spread across more than one element (row, column, box). I do not find them easy.

Keith
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dldcamp



Joined: 29 May 2007
Posts: 15
Location: Florida

PostPosted: Sun Jun 10, 2007 1:03 pm    Post subject: Still confused Reply with quote

I have a 15 (C4,R2), 58(C4,R4), and 18(C4, R9). But, I can't find the w-y wing. What boxes are the 15, 58, 18 in? And, which is the pivot?
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Sun Jun 10, 2007 7:46 pm    Post subject: Two <1>s eliminated Reply with quote

In Keith's XY-wing, <1> is eliminated from both R1C6 and R3C6.

dldcamp: The 18 is in R6C6 (marked @). The logic:

R4C4 is either <5> or <8>.
If R4C4 is <5>, R2C4 is <1>.
If R4C4 is <8>, R6C6 is <1>.
Thus, either R2C4 is <1> or R6C6 is <1>.
Any cell that can "see" both of these cells cannot be <1>.
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