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Mon Feb 14th VH

 
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hughwill



Joined: 05 Apr 2010
Posts: 167
Location: Birmingham UK

PostPosted: Mon Feb 14, 2011 11:17 am    Post subject: Mon Feb 14th VH Reply with quote

I'm not so hot on these- was this a more complicated VH than usual? After the
obvious (and unnecessary?) 25 UR I got a colouring on a chain of 6's removing
6 from C1 and then a 246 XY wing pivoting on C8. Was there an easier way?

By the way- where is everyone? Very late for a first post.....


After basics
Code:

+----------------+----------+--------------+
| 69    1    3   | 8 4  69  | 26   7  5    |
| 469   456  569 | 2 7  169 | 1368 38 3468 |
| 246   7    8   | 5 3  16  | 16   46 9    |
+----------------+----------+--------------+
| 38    2358 245 | 6 25 7   | 9    1  238  |
| 1     26   7   | 9 8  3   | 5    46 246  |
| 368   9    25  | 1 25 4   | 368  38 7    |
+----------------+----------+--------------+
| 5     36   16  | 4 9  8   | 7    2  136  |
| 34689 3468 69  | 7 1  2   | 368  5  368  |
| 7     28   12  | 3 6  5   | 4    9  18   |
+----------------+----------+--------------+

Play this puzzle online at the Daily Sudoku site
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Stanley P



Joined: 27 Feb 2008
Posts: 16
Location: Tennessee, USA

PostPosted: Mon Feb 14, 2011 1:32 pm    Post subject: Reply with quote

I had slightly different basics and found an xyz wing on 126 in boxes 2 and 3. That did it for me.
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Marty R.



Joined: 12 Feb 2006
Posts: 5123
Location: Rochester, NY, USA

PostPosted: Mon Feb 14, 2011 4:41 pm    Post subject: Reply with quote

Like Stanley, I had a 2 in r3c7 and used the XYZ-Wing. However, in Hugh's grid the 16 pair in row 3 would knock out the other 6s in that row and finish it off.
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keith



Joined: 19 Sep 2005
Posts: 3150
Location: near Detroit, Michigan, USA

PostPosted: Mon Feb 14, 2011 4:57 pm    Post subject: Reply with quote

After basics:
Code:
+-------------------+-------------------+-------------------+
| 269   1     3     | 8     4     69    | 26    7     5     |
| 469   456   4569  | 2     7     169   | 1368  38    3468  |
| 246   7     8     | 5     3     16    | 126   46    9     |
+-------------------+-------------------+-------------------+
| 348   23458 245   | 6     25    7     | 9     1     2348  |
| 1     246   7     | 9     8     3     | 5     46    246   |
| 368   9     25    | 1     25    4     | 368   38    7     |
+-------------------+-------------------+-------------------+
| 5     36    16    | 4     9     8     | 7     2     136   |
| 34689 3468  469   | 7     1     2     | 368   5     368   |
| 7     28    12    | 3     6     5     | 4     9     18    |
+-------------------+-------------------+-------------------+
Keith
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cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Mon Feb 14, 2011 6:31 pm    Post subject: Reply with quote

R3C78 cannot be a 1 and 6 or a 2 and 6. Can only be a 1 and 4, 2 and 4, or 6 and 4. Ergo R3C8 has to be a 4.

I think thatís an APE (aligned pair exclusion). Better than looking for wings.
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Ema Nymton



Joined: 17 Apr 2009
Posts: 87

PostPosted: Tue Feb 15, 2011 1:17 pm    Post subject: Reply with quote

.

I conceed defeat. This is one subtle puzzle.

Code:

+------------------+----------+--------------+
| 269   1     3    | 8 4  69  | 26   7  5    |
| 469   456   4569 |*2 7  169 | 1368 38 368  |
| 26    7     8    | 5 3  16  | 126  4  9    |
+------------------+----------+--------------+
| 348   23458 245  | 6 25 7   | 9    1  2348 |
| 1     24    7    | 9 8  3   | 5    6  24   |
| 368   9     256  | 1 25 4   | 38   38 7    |
+------------------+----------+--------------+
| 5     36    16   | 4 9  8   | 7   *2  136  |
| 34689 3468  469  | 7 1  2   | 368  5  368  |
| 7     28    12   | 3 6  5   | 4    9  18   |
+------------------+----------+--------------+


The key was '2' in r2c4 and r7c8.
Thank you for the challenge.

Ema Nymton
.
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tlanglet



Joined: 17 Oct 2007
Posts: 2461
Location: Northern California Foothills

PostPosted: Tue Feb 15, 2011 3:59 pm    Post subject: Reply with quote

cgordon wrote:
R3C78 cannot be a 1 and 6 or a 2 and 6. Can only be a 1 and 4, 2 and 4, or 6 and 4. Ergo R3C8 has to be a 4.

I think thatís an APE (aligned pair exclusion). Better than looking for wings.


I agree with your analysis and that the pattern is an APE; it is also an xyz-wing as previously noted by Stanley and Marty. However I question your definition of "Better". In general, looking for an APE is more complex and cumbersome that looking for an xyz-wing, which is also frequently an APE pattern.

I guess "Better" truly depends on what motivates us to play Sudoku.

Ted
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