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Puzzle 10/02/17 (A)

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Wed Feb 17, 2010 6:22 pm    Post subject: Puzzle 10/02/17 (A) Reply with quote

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

Play this puzzle online at the Daily Sudoku site
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Marty R.



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

PostPosted: Thu Feb 18, 2010 5:44 am    Post subject: Reply with quote

My typical hodgepodge of moves, including an XY-Chain, ER, XY, X and XY.
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tlanglet



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

PostPosted: Thu Feb 18, 2010 3:44 pm    Post subject: Reply with quote

I fell into a three step solution.

Quote:
ER on 8 with hinge in box1 and strong link in row9, which sets up a
xy-wing 78-9 with vertex 78 in r2c9,
a Type 1 UR 78 in r68c13 completes the puzzle.

Ted
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Wendy W



Joined: 04 Feb 2008
Posts: 144

PostPosted: Fri Feb 19, 2010 1:13 am    Post subject: Reply with quote

I went the chain route with a skyscraper and an XY wing along the way. I was really looking for a way to use all those 789 triples but couldn't find one.
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oaxen



Joined: 10 Jul 2006
Posts: 96

PostPosted: Fri Feb 19, 2010 9:44 am    Post subject: Two stepper Reply with quote

Congratulations Danny!
This was a puzzle that even for a solver with the simplified Oaxen-thread method needed two steps. Like Wendy says, there were a lot of 789 who eventually blocked the first chain.

Lars
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Sat Feb 20, 2010 3:24 am    Post subject: Reply with quote

Wendy W wrote:
I went the chain route with a skyscraper and an XY wing along the way. I was really looking for a way to use all those 789 triples but couldn't find one.


one way is to use them in a ALS stucture.

Code:
+--------------------+----------------+-------------+
| 3      (789)  4    | 1    29  2789  | 5  89   6   |
| 78(9)  1      2    | 6    5   78(9) | 4  3    78  |
| 6      (789)  5    | 789  3   4     | 1  289  278 |
+--------------------+----------------+-------------+
| 1      4      89   | 79   6   279   | 3  28   5   |
| 5      2      6    | 3    8   1     | 7  4    9   |
| 789    3789   3789 | 4    29  5     | 6  1    28  |
+--------------------+----------------+-------------+
| 2      3569   39   | 59   1   (69)  | 8  7    4   |
| 789    5789   789  | 589  4   3     | 2  6    1   |
| 4      -8(6)  1    | 2    7   8(6)  | 9  5    3   |
+--------------------+----------------+-------------+


notice that if the 9's in the 789 triples in r13c2 are false, then the 78 naked pair is left. this naked pair would eliminate the 8 in r9c2.

if the 9's are true, then...
(9)r13c2 - (9)r2c1 = (9)r2c6 - (9=6)r7c6 - (6)r9c6 = (6)r9c2
6 is true in r9c2

either way, 8 is false in r9c2. 6 can be placed.
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Wendy W



Joined: 04 Feb 2008
Posts: 144

PostPosted: Sat Feb 20, 2010 10:41 pm    Post subject: Reply with quote

Wow, Norm, that's really clever! Thank you.
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