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Puzzle 11/04/28: ~ (late) 4-cell XY-Chain

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Thu Apr 28, 2011 9:22 pm    Post subject: Puzzle 11/04/28: ~ (late) 4-cell XY-Chain Reply with quote

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

Play this puzzle online at the Daily Sudoku site
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Fri Apr 29, 2011 5:57 pm    Post subject: Reply with quote

Note: This is the last "Moderate" puzzle containing a 4-cell XY-Chain in my solver's solution. I've deleted the others from my puzzles remaining to be posted.

Regards, Danny
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Marty R.



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

PostPosted: Sat Apr 30, 2011 5:00 am    Post subject: Reply with quote

No early or late four-cell chains for me.

M-Wing
XY-Loop
XYZ-Wing
Medusa
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peterj



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

PostPosted: Sat Apr 30, 2011 8:28 am    Post subject: Reply with quote

I couldn't find one either! This was my path...
Quote:
w-wing(14) (4=1)r6c9 - r1c9=r3c8 - (1=4)r7c8 ; r8c9<>4
xy-chain (1=3)r1c9 - (3=1)r1c2 - (1=4)r5c2 - (4=5)r8c2 - (5=4)r8c7 - (4=1)r7c8 ; r3c8<>1, r8c9<>1
I also tried playing the xyz-wing(49-1) but I still couldn't find a 4-cell xy-chain! So maybe they are not easy after all.
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tlanglet



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

PostPosted: Sat Apr 30, 2011 2:27 pm    Post subject: Reply with quote

I found a one step AUR but not the "brass ring".

AUR(14)r68c79 external sis: r7c8=1,r8c2=4; r7c8=1
(4)r8c2-(4=1)r5c2-r13c2=r3c3-r3c8=(1)r7c8;

Ted
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Sat Apr 30, 2011 2:55 pm    Post subject: Reply with quote

I guess it takes the righ combination of earlier steps to reach the 4-cell XY-Chain.

Code:
 <35+1>  XYZ-Wing r3c3/r1c2+r3c8         <> 1    r3c2
 <49+1>  XYZ-Wing r8c9/r7c8+r8c5         <> 1    r8c7

   c67   X-Wing                          <> 9    r2c59
 r38     X-Wing                          <> 9    r2c59

 r24c23  <38> UR Type 4.2243             <> 3    r2c23
 r23c24  <37> UR Type 4.2243             <> 3    r23c2

 +-----------------------------------------------------+
 |  9    13   6    |  4    8    5    |  7    2    13   |
 |  2    578  58   |  37   16   19   |  49   45   36   |
 |  4    57   13   |  37   69   2    |  8    15   69   |
 |-----------------+-----------------+-----------------|
 |  6    38   38   |  1    4    7    |  2    9    5    |
 |  5    14   14   |  9    2    8    |  3    6    7    |
 |  7    2    9    |  6    5    3    |  1    8    4    |
 |-----------------+-----------------+-----------------|
 |  8    9    7    |  5    3    14   |  6    14   2    |
 |  3    45   2    |  8    19   6    |  45   7    19   |
 |  1    6    45   |  2    7    49   |  459  3    8    |
 +-----------------------------------------------------+
 # 31 eliminations remain

 (5=8)r2c3 - (8=3)r4c3 - (3=1)r3c3 - (1=5)r3c8  =>  r2c8,r3c2<>5

Of course, the BUG+2 => r2c3<>5 would probably be easier.
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