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Free Press July 19, 2013

 
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keith



Joined: 19 Sep 2005
Posts: 3163
Location: near Detroit, Michigan, USA

PostPosted: Mon Jul 22, 2013 3:26 pm    Post subject: Free Press July 19, 2013 Reply with quote

Not yet started ...

Code:
Puzzle: FP071913
+-------+-------+-------+
| 7 . . | . . . | . 5 4 |
| . . . | 8 . 5 | . . 6 |
| . . . | . 2 . | 7 . . |
+-------+-------+-------+
| 1 . 3 | . 8 . | 9 . . |
| . . . | 9 . 7 | . . . |
| . . 4 | . 6 . | 2 . 3 |
+-------+-------+-------+
| . . 7 | . . . | . . . |
| 8 . . | 1 5 3 | . . . |
| 4 3 . | . . . | . . 8 |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

Keith
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keith



Joined: 19 Sep 2005
Posts: 3163
Location: near Detroit, Michigan, USA

PostPosted: Mon Jul 22, 2013 9:41 pm    Post subject: Reply with quote

Solved by multiple attacks on 6.

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5155
Location: Rochester, NY, USA

PostPosted: Tue Jul 23, 2013 1:08 am    Post subject: Reply with quote

This is the same puzzle that Dan posted on the other site as L.A. Times Diabolical of 7-19 and I've been struggling with that.
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Marty R.



Joined: 12 Feb 2006
Posts: 5155
Location: Rochester, NY, USA

PostPosted: Tue Jul 23, 2013 1:24 am    Post subject: Reply with quote

I struggled, using a W-Wing on 26, an XY-Wing on 25-6 and an XY-Loop that started and ended in c1.
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keith



Joined: 19 Sep 2005
Posts: 3163
Location: near Detroit, Michigan, USA

PostPosted: Tue Jul 23, 2013 11:12 am    Post subject: Reply with quote

After basics:
Code:
+-------------------+-------------------+-------------------+
| 7     268   268   | 36    1     9     | 38    5     4     |
| 3     4     9     | 8     7     5     | 1     2     6     |
| 56    1568  1568  | 346   2     46    | 7     38    9     |
+-------------------+-------------------+-------------------+
| 1     567   3     | 24    8     24    | 9     67    57    |
| 256   2568  2568  | 9     3     7     | 4568  1468  15    |
| 9     78    4     | 5     6     1     | 2     78    3     |
+-------------------+-------------------+-------------------+
|25-6  125-69 7     |#26    4     8     | 356   1369  125   |
| 8     269  #26    | 1     5     3     | 46    4679  27    |
| 4     3    *1256  | 7     9    *26    | 56    16    8     |
+-------------------+-------------------+-------------------+

W-wing.

After that, two XY-wings 25-6 and 25-6 leave us here:
Code:
+----------------+----------------+----------------+
| 7   #268  28   |#36   1    9    | 38   5    4    |
| 3    4    9    | 8    7    5    | 1    2    6    |
| 56   1568 158  | 34   2    46   | 7    38   9    |
+----------------+----------------+----------------+
| 1   *567  3    | 24   8    24   | 9   *67   57   |
| 256  2568 2568 | 9    3    7    | 4568 1468 15   |
| 9    78   4    | 5    6    1    | 2    78   3    |
+----------------+----------------+----------------+
| 25   1259 7    |#26   4    8    | 356  1369 125  |
| 8    269  26   | 1    5    3    | 46   4679 27   |
| 4    3    1256 | 7    9   #26   | 56  1-6   8    |
+----------------+----------------+----------------+

Multicoloring (Extended skyscraper) takes out 6 in R9C8.

Keith
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tlanglet



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

PostPosted: Tue Jul 23, 2013 12:35 pm    Post subject: Reply with quote

I believe that we call this a xy-wing(67-1) with pseudocell pincer (17)r45c9......

Code:
 
 *--------------------------------------------------------------------*
 | 7      268    268    | 36     1      9      | 38     5      4      |
 | 3      4      9      | 8      7      5      | 1      2      6      |
 | 56     1568   1568   | 346    2      46     | 7      38     9      |
 |----------------------+----------------------+----------------------|
 | 1      567    3      | 24     8      24     | 9     b67    c57     |
 | 256    2568   2568   | 9      3      7      | 4568  -1468  d15     |
 | 9      78     4      | 5      6      1      | 2      78     3      |
 |----------------------+----------------------+----------------------|
 | 256    12569  7      | 26     4      8      | 356    1369  -125    |
 | 8      269    26     | 1      5      3      | 46     4679   27     |
 | 4      3      1256   | 7      9      26     | 56    a16     8      |
 *--------------------------------------------------------------------*

xy-wing(76-1): (1=6)r9c8-(6=7)r4c8-(7=5)r4c9-(5=1)r5c9 => r5c8,r7c9<>1

Ted
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keith



Joined: 19 Sep 2005
Posts: 3163
Location: near Detroit, Michigan, USA

PostPosted: Tue Jul 23, 2013 3:21 pm    Post subject: Reply with quote

Ted,

Very nice!

I must say though that the way I solve puzzles would tend to find the solution I posted, not a short chain like yours.

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5155
Location: Rochester, NY, USA

PostPosted: Tue Jul 23, 2013 6:10 pm    Post subject: Reply with quote

keith wrote:
Ted,

Very nice!

I must say though that the way I solve puzzles would tend to find the solution I posted, not a short chain like yours.

Keith


I might've found the chain if I reached the point where looking for chains was my only option, but I'd never have recognized it as an XY-Wing with pseudo cell pincer.
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tlanglet



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

PostPosted: Tue Jul 23, 2013 8:45 pm    Post subject: Reply with quote

I was checking for xy-wings when I noted the solution. It just jumped out at me since three of the four cells were literally adjacent in box 6. In any case, I normally/frequently look one step past a bivalue cell that is useful but does not complete the xy-wing, and if the additional step is successful, I will continue the process looking for a useful xy-chain.

Ted
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