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Puzzle 10/01/18 (C)

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Tue Jan 19, 2010 12:07 am    Post subject: Puzzle 10/01/18 (C) Reply with quote

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

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: Tue Jan 19, 2010 2:06 pm    Post subject: Reply with quote

Here is a two stepper with a somewhat different second move (for me at least).

The first move is a w-wing 12 in r1c6 & r9c4 with strong link 2 in r38c5.

This results in the following grid after cleanup including a naked quad or hidden pair 17.
Code:
  *-----------------------------------------------------------*
 | 6     47    5     | 9     8     1     | 27   #247   3     |
 | 3     47    12    | 24    5     6     | 8    #147   9     |
 | 9     8     12    | 234   23    7     | 15    6     45    |
 |-------------------+-------------------+-------------------|
 | 7     5     6     | 23    4     23    | 9     8     1     |
 | 8     2     3     | 6     1     9     | 4     5     7     |
 | 1     9     4     | 5     7     8     | 236   23    26    |
 |-------------------+-------------------+-------------------|
 | 25    1     8     | 7     9     2345  | 2356  234   2456  |
 | 25    6     9     | 8     23    2345  | 17    17    245   |
 | 4     3     7     | 1     6     25    | 25    9     8     |
 *-----------------------------------------------------------*

Now notice the UR 47 in r12c28. To prevent the deadly pattern, either r1c8=2 or r2c8=1 which forms a pseudocell 12 in r12c8, marked #. This pseudocell becomes a pincer for a xy-wing -127 with the vertex 27 in r1c7 and second pincer 17 in r8c7 to delete the 1 in r3c7 and complete the puzzle.

Ted
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

PostPosted: Tue Jan 19, 2010 4:27 pm    Post subject: Reply with quote

tlanglet wrote:
Here is a two stepper with a somewhat different second move (for me at least).
Wow! nice find! Very Happy I was stuck with a three stepper -- an xyz-wing sandwiched with a couple of w-wings.

I have started looking for psuedo cells but it hurts my mind. Shocked
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Tue Jan 19, 2010 6:55 pm    Post subject: Reply with quote

tlanglet wrote:
Now notice the UR 47 in r12c28. To prevent the deadly pattern, either r1c8=2 or r2c8=1 which forms a pseudocell 12 in r12c8, marked #. This pseudocell becomes a pincer for a xy-wing -127 with the vertex 27 in r1c7 and second pincer 17 in r8c7 to delete the 1 in r3c7 and complete the puzzle.

I second Dan's Wow!

An impressive way to use what appears to be a useless UR!

Congratulations, Danny

Addendum: Hey Ted, an additional congratulations on using the pseudo-cell properly. It's only "viable" in [b3] and [c8] -- which is how you used it in the XY-Wing.
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Marty R.



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

PostPosted: Wed Jan 20, 2010 11:35 pm    Post subject: Reply with quote

I'm not nearly clever enough to spot and use that pseudo cell. But, after playing the 12 W-Wing, I used the 47 UR to finish because both the 1 and 2 that are needed to kill the DP will force r2c8=1.
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