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MM 1321 2/20/09

 
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Fri Feb 20, 2009 11:01 pm    Post subject: MM 1321 2/20/09 Reply with quote

Code:

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

Play this puzzle online at the Daily Sudoku site
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tlanglet



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

PostPosted: Sat Feb 21, 2009 10:20 pm    Post subject: Reply with quote

I did not find may choices, but then a one-step solution.

Quote:
A w-wing<37> in r3c5 & r8c3 with strong ling on <3> in box<8> did not provide any eliminations, but transporting the <7> from r8c3 to r5c4 via r5c3 breaks it open.


Ted
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Marty R.



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

PostPosted: Fri Feb 27, 2009 5:42 am    Post subject: Reply with quote

I played the Type 2 UR on 56. Then a W-Wing on 79 eliminated a candidate, followed by a pincer transport which finished it.
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Fri Feb 27, 2009 7:21 am    Post subject: Reply with quote

Code:
 after basics: a DP and an M-Wing
 +--------------------------------------------------------------+
 |  3     78    45+9  |  457   1     6     |  79    2     48    |
 |  1     78    45    |  457+3 2     9     |  37    6     48    |
 |  49    2     6     | d347  e37    8     |  39-7  5     1     |
 |--------------------+--------------------+--------------------|
 |  267   3     1     |  279   679   5     |  8     4     67    |
 |  56    4    b27    | c27    8     3     |  1     9     56    |
 |  567   9     8     |  1     67    4     |  2     3     567   |
 |--------------------+--------------------+--------------------|
 |  8     1     49    |  6     49    2     |  5     7     3     |
 |  79    6    a37    |  9-3   5     1     |  4     8     2     |
 |  24    5     2-3   |  8    f34    7     |  6     1     9     |
 +--------------------------------------------------------------+
 # 44 eliminations remain

Skip these UR eliminations.

Code:
 r6      UR Type 2 [r56c19] in <56>      <> 7    [r6c5]
         UR        [r12c34] in <45>      <> 4    [r1c4]

I believe there is a <4578> DP in [r12c2349]. If so, then one of the following statements must be true.

Code:
(9)r1c3 - (9=7)r1c7 - (7)r3c7
(3)r2c4 - (3=7)r2c7 - (7)r3c7

This now opens up a (generalized) M-Wing elimination that cracks the puzzle.

Code:
Eureka PPB

(3=7)r8c3 - (7)r5c3 = (7)r5c4 - (7)r3c4 = (7-3)r3c5 = (3)r9c5 => [r8c4],[r9c3]<>3

Ping Pong Balls (PPB): An AIC that starts and ends with a strong inference. (Courtesy of a suggestion by storm_norm!)
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Steve R



Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England

PostPosted: Sat Feb 28, 2009 1:43 pm    Post subject: Reply with quote

The grid is riddled with a bewildering number of deadly patterns so itís easy to miss the most helpful.

To avoid a (567) in r456c19, 2 must be placed in r4c1 and singles follow.

Steve
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