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Puzzle NR 09/11/25 (B)

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Wed Nov 25, 2009 11:59 pm    Post subject: Puzzle NR 09/11/25 (B) Reply with quote

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

Play this puzzle online at the Daily Sudoku site
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Thu Nov 26, 2009 3:00 am    Post subject: Reply with quote

Code:
+--------------+------------------+--------------------+
| 6     1   4  | 5     9    (38)  | 2     37-8   37-8  |
| 5     8   7  | 2346  36   2346  | 1     (34)   9     |
| 3     9   2  | 4-8   7    1     | 5     6      (48)  |
+--------------+------------------+--------------------+
| 9     5   16 | 7     4    6(3)  | 8     1(3)   2     |
| 8     47  3  | 1     2    9     | 47    5      6     |
| 47    2   16 | 368   368  5     | 3479  13479  1347  |
+--------------+------------------+--------------------+
| 1247  6   5  | 9     38   23478 | 347   13478  13478 |
| 147   47  9  | 3468  5    34678 | 3467  2      13478 |
| 247   3   8  | 246   1    2467  | 4679  479    5     |
+--------------+------------------+--------------------+

(8=3)r1c6 - (3)r4c6 = (3)r4c8 - (3=4)r2c8 - (4=8)r3c9; r1c89 and r3c4 <> 8

leads to
Quote:
xy-wing {3,6,9}
followed by remote pair 47
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Marty R.



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

PostPosted: Thu Nov 26, 2009 8:11 pm    Post subject: Reply with quote

I needed an ER on 3 to get going. Then it was Remote Pairs on 47, multi-coloring on 4 (not needed) and an XY-Wing on 369.
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Wed Dec 02, 2009 3:50 pm    Post subject: Reply with quote

I started with two AICs found by extending the vertex of potential xy-wings.

(4=8)r3c4 - (8=3)r1c6 - (3)r4c6 = (3)r4c8 - (3=4)r2c8; r2c46, r3c9<>4

(1=3)r4c8 - (3=9)r6c7 - (9=6)r9c7 - (6)r9c4 = (6)r6c4 - (6=1)r6c3; r4c3, r6c8<>1

A 6-cell Remote Pair on 47 completed the puzzle.

Ted
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Wed Dec 02, 2009 8:07 pm    Post subject: Reply with quote

Reordering Marty's solution to be: ER, XY-Wing, and Remote Pair. Now, there's an alternative to the Remote Pair.

Code:
 <37> UR r16c89 => r6c8=9 and/or r6c9=4
 +------------------------------------------------------+
 |  6    1    4    |  5    9    8    |  2   *37   *37   |
 |  5    8    7    |  3    6    2    |  1    4     9    |
 |  3    9    2    |  4    7    1    |  5    6     8    |
 |-----------------+-----------------+------------------|
 |  9    5    6    |  7    4    3    |  8    1     2    |
 |  8    47   3    |  1    2    9    |  47   5     6    |
 |  47   2    1    |  6    8    5    |  39  *37+9 *37+4 |
 |-----------------+-----------------+------------------|
 |  2    6    5    |  9    3    47   |  47   8     1    |
 |  1    47   9    |  8    5    467  |  36   2     347  |
 |  47   3    8    |  2    1    467  |  69   79    5    |
 +------------------------------------------------------+
 # 23 eliminations remain

As it turns out, both choices are true. So, how do you proceed?
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Marty R.



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

PostPosted: Wed Dec 02, 2009 10:25 pm    Post subject: Reply with quote

If r6c8=9>>r9c8=7>>r9c1=4. This now is a pincer with r6c9, removing the 4 from r6c1.
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Thu Dec 03, 2009 1:05 am    Post subject: Reply with quote

Marty, that is a Cool move. It is like patting someone on the shoulder with one hand to distract them while stealing their popcorn with the other hand.

Ted
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