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Free Press March 18, 2011

 
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Fri Mar 18, 2011 4:35 pm    Post subject: Free Press March 18, 2011 Reply with quote

Not yet done. Does require advanced moves.
Code:
Puzzle: FP031811
+-------+-------+-------+
| . . . | . 3 9 | . 4 . |
| . . 7 | 8 . . | 3 6 . |
| . . . | . . . | . 7 . |
+-------+-------+-------+
| 5 . . | 4 . 1 | . . . |
| 4 . . | . 5 . | . . 2 |
| . . . | 9 . 8 | . . 7 |
+-------+-------+-------+
| . 1 . | . . . | . . . |
| . 3 . | . . 7 | 9 . . |
| . 2 . | 3 1 . | . . 4 |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

Keith
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Marty R.



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

PostPosted: Fri Mar 18, 2011 6:46 pm    Post subject: Reply with quote

Quote:
XY-Chain. The 9 in r5c8 proves a 1 in r8c9; r8c8<>1
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Fri Mar 18, 2011 8:17 pm    Post subject: Reply with quote

After basics:
Code:
+-------------+-------------+-------------+
|-12  58  6   | 7   3   9   |125f 4   158 |
| 12d 59  7   | 8   4   25  | 3   6  -159c|
| 89  4   3   | 1   6   25  | 25  7   89  |
+-------------+-------------+-------------+
| 5   89b 2   | 4   7   1   | 68  39  36  |
| 4   7   89  | 6   5   3   | 18e 19a 2   |
| 3   6   1   | 9   2   8   | 4   5   7   |
+-------------+-------------+-------------+
| 78  1   58  | 25  9   4   | 567 23  36  |
| 6   3   4   | 25  8   7   | 9   12  15  |
| 79  2   59  | 3   1   6   | 57  8   4   |
+-------------+-------------+-------------+

M-wing: 9 in a forces 9 in c (coloring via b). a and d are pincers on 1. Transport a through e to f, making the eliminations shown. Bringing us here:
Code:
+-------------+-------------+-------------+
| 2   58  6   | 7   3   9   | 1-5 4   158@|
| 1   59  7   | 8   4   2   | 3   6   59  |
| 89  4   3   | 1   6   5   | 2   7   89  |
+-------------+-------------+-------------+
| 5   89  2   | 4   7   1   | 68  39  36  |
| 4   7   89  | 6   5   3   | 18  19  2   |
| 3   6   1   | 9   2   8   | 4   5   7   |
+-------------+-------------+-------------+
| 78  1   58  | 25  9   4   |567@ 23  36  |
| 6   3   4   | 25  8   7   | 9   12  1-5 |
| 79  2   59  | 3   1   6   | 57  8   4   |
+-------------+-------------+-------------+
Which is a BUG+2 - one or both of the cells marked @ is 5.

Keith
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Fri Mar 18, 2011 9:40 pm    Post subject: Reply with quote

In the second grid above, there are other ways to make the same eliminations:

Code:
+-------------+-------------+-------------+
| 2   58  6   | 7   3   9   | 1-5 4   158 |
| 1   59d 7   | 8   4   2   | 3   6   59a |
| 89  4   3   | 1   6   5   | 2   7   89  |
+-------------+-------------+-------------+
| 5   89  2   | 4   7   1   | 68  39  36  |
| 4   7   89  | 6   5   3   | 18  19  2   |
| 3   6   1   | 9   2   8   | 4   5   7   |
+-------------+-------------+-------------+
| 78  1   58  | 25  9   4   | 567 23  36  |
| 6   3   4   | 25  8   7   | 9   12  1-5 |
| 79  2   59c | 3   1   6   | 57b 8   4   |
+-------------+-------------+-------------+
a and b are M-wing pincers on 5, since 9 in a forces 9 in c.

Another way to look at it is c and d are not just a W-wing - they are a remote pair since they are connected by strong links on 9. Then, make the one-link extension of both ends, d to a and c to b, to establish the pincers on 5 at a and b.

Keith
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tlanglet



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

PostPosted: Sat Mar 19, 2011 1:31 am    Post subject: Reply with quote

I initially found three different anp() moves that reduced the puzzle to the BUG+2 posted by Keith, but then I spotted a flightless w-wing(58)r1c2|r7c3 with SL (8)b4
(The w-wing (59)r2c2/r9c3 with SL b4 provides the same pincers on 5)

I could not find a transport that provided a deletion on (5), but with two pincer transports; r7c8,r8c4<>2
(5)r1c2-(8)r1c2=r4c2-(8=9)r5c3-(9=1)r5c8-(1=2)r8c8
||
(5)r7c3-(5=2)r7c4

Fun puzzle.......

Ted
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Sat Mar 19, 2011 2:23 am    Post subject: Reply with quote

tlanglet wrote:
Fun puzzle.......
Ted

I thought so too. Had to break out the Sonoma juice.

It's too bad that these Friday Freep puzzles are so variable, when some of them are quite good.

Keith
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tlanglet



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

PostPosted: Sat Mar 19, 2011 2:39 am    Post subject: Reply with quote

keith wrote:
tlanglet wrote:
Fun puzzle.......
Ted

I thought so too. Had to break out the Sonoma juice
Keith


I agree about breaking out the juice, but I prefer the Zinfandels from the Northern Foothills of California where I live.

Ted
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Sat Mar 19, 2011 3:52 am    Post subject: Reply with quote

Code:
 after basics
 +-----------------------------------------------------+
 |  12   58   6    |  7    3    9    | #125  4   *158  |
 |  12   59   7    |  8    4    25   |  3    6   #159  |
 |  89   4    3    |  1    6    25   |  2-5  7    89   |
 |-----------------+-----------------+-----------------|
 |  5    89   2    |  4    7    1    |  68   39   36   |
 |  4    7    89   |  6    5    3    |  18   19   2    |
 |  3    6    1    |  9    2    8    |  4    5    7    |
 |-----------------+-----------------+-----------------|
 |  78   1    58   |  25   9    4    | #567  23   36   |
 |  6    3    4    |  25   8    7    |  9    12   15   |
 |  79   2    59   |  3    1    6    |  57   8    4    |
 +-----------------------------------------------------+
 # 35 eliminations remain

BUG+4:

(=5)r1c7|r2c9|r7c7  =>  r3c7<>5   -or-

(=1)r1c9 - (1=2)r1c1 - r2c2 = r2c6 - (2=5)r3c6  =>  r3c7<>5

Now, where did I put the Skyy vodka and Bloody Mary mix?
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Sat Mar 19, 2011 12:11 pm    Post subject: Reply with quote

Danny,

That is amazing, I would never have thought to look for it.

Your second chain is a little simpler if you note that in R1, 1 in R1C8 forces 5 in R1C7, and then the first chain applies.

And, this takes us to the BUG+2, right?

Keith
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Sat Mar 19, 2011 4:17 pm    Post subject: Reply with quote

keith wrote:
Your second chain is a little simpler if you note that in R1, 1 in R1C9 forces 5 in R1C7, and then the first chain applies.

And, this takes us to the BUG+2, right?

It was late and I was tired. However, I didn't use any of the 5s from the BUG+4 in the second chain because they were presumed false from the "-or-" condition. What I should have done is show: (5=12)r1c71 - (1)r1c9 to exclude that possibility. Essentially, if the 5s are false, then r1c9=1 is also false. Maybe this is really a BUG+3 scenario?

There were so many XY-Chains that crack the puzzle, I was sure that any elimination in a bivalue cell would crack the puzzle. My oversight!

Thanks for cleaning up my sloppiness!!!

Regards, Danny
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