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Puzzle 10/10/31: B5 XY

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Sat Oct 30, 2010 5:36 pm    Post subject: Puzzle 10/10/31: B5 XY Reply with quote

I'm hanging up my hat on posting puzzles. Today's puzzles are the last.

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

Play this puzzle online at the Daily Sudoku site
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK

PostPosted: Mon Nov 01, 2010 7:44 am    Post subject: Reply with quote

This was a notch tougher than the others so far - for me anyway. Two steps and a chain using all those 57s..
Quote:
ER(5) ; (5)r4c2=r9c2 - r9c79=r78c9 ; r4c9<>5
xy-chain ; (2=5)r3c6 - (5=7)r5c6 ... -(5=7)r9c2 - (7=35)r39c7 - (5=1)r1c7 - (1=7)r2c7 - (7=2)r2c9 ; r3c9<>2
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Marty R.



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

PostPosted: Thu Nov 04, 2010 10:37 pm    Post subject: Reply with quote

ER (5)
XYZ-Wing (135)
XY-Wing(375), flightless with transport; r6c5<>5

There were overlapping XYZ-Wings in box 2 and I was going to be a genius and play them simultaneously, rather than playing one which would destroy the other. However, it wasn't necessary since playing the one accomplished the same thing.
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Fri Nov 05, 2010 12:28 am    Post subject: Reply with quote

I originally tried to get a BUG+4 to work, but became frustrated. Then I saw the same 57s mentioned by Peter and thought of a DP ala Ted. But, I again ended up frustrated.

Code:
 after the ER and 2x XYZ-Wings mentioned by Marty

 <57> DP in (*) leads to: r6c6<>5, r9c3<>7

 ... which leaves a BUG+2
 (2)r8c7 - (2=8)r9c6 - (8)r9c9
 (3                  -  8)r9c9
 +-----------------------------------------------------+
 |  7    23   4    |  13   25   9    |  15   8    6    |
 |  5    23   6    |  13   8    4    |  17   9    27   |
 |  9    8    1    |  7    6    25   |  35   4    23   |
 |-----------------+-----------------+-----------------|
 |  1   *57   3    |  2    9    6    |  8   *57   4    |
 |  2    9    8    |  4    3   *57   |  6   *57   1    |
 |  4    6   *57   |  8    15  *57+1 |  2    3    9    |
 |-----------------+-----------------+-----------------|
 |  8    1    9    |  6    7    3    |  4    2    5    |
 |  3    4    27   |  5    12   128  |  9    6    78   |
 |  6   *57  *57+2 |  9    4    28   |  37   1    378  |
 +-----------------------------------------------------+
 # 31 eliminations remain

So I cheated and checked my solver's output. _ Rolling Eyes _

Code:
 after the ER and 2x XYZ-Wings mentioned by Marty

 internally extended <27> W-Wing
 (7=2)r2c9 - r2c2 = r1c2 - r1c5 = r8c5 - (2=7)r8c3  =>  r8c9<>7

 ... or a 7-cell XY-Chain if you include r6c5
 +-----------------------------------------------------+
 |  7   *23   4    |  13  *25   9    |  15   8    6    |
 |  5   *23   6    |  13   8    4    |  17   9   #27   |
 |  9    8    1    |  7    6    25   |  35   4    23   |
 |-----------------+-----------------+-----------------|
 |  1    57   3    |  2    9    6    |  8    57   4    |
 |  2    9    8    |  4    3    57   |  6    57   1    |
 |  4    6    57   |  8   @15   157  |  2    3    9    |
 |-----------------+-----------------+-----------------|
 |  8    1    9    |  6    7    3    |  4    2    5    |
 |  3    4   #27   |  5   *12   128  |  9    6    8-7  |
 |  6    57   257  |  9    4    28   |  37   1    378  |
 +-----------------------------------------------------+
 # 31 eliminations remain
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tlanglet



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

PostPosted: Fri Nov 12, 2010 8:45 pm    Post subject: Reply with quote

I used three steps, but the first did not contribute to the solution.

ANP(2=57)r9c23-(57=3)r9c7-(3=5=4=2)r3c786; r9c6<>2
ER 5 with hinge b9, SL r59c2; r4c9<>5
ANP(35=2)r3c79-(2=7)r2c9-r789c9=r9c7-r9c2=r4c2-r6c3=r6c56-(7=5)r5c6; r3c6<>5

Ted
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