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Puzzle 10/10/11: C XY

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Mon Oct 11, 2010 3:17 am    Post subject: Puzzle 10/10/11: C XY Reply with quote

Now, don't work too hard resolving box 5. _ Laughing _

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

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: Mon Oct 11, 2010 3:01 pm    Post subject: Reply with quote

I initially found two xy-loops, and was looking for another when I stumbled on a one step contradiction chain.

Quote:
xy-loop r1c2,r1c9,r8c9,r8c2, r1c2; r1c6<>7,r37c9<>5,r8c6<>2,r3c2<>3
xy-loop r4c2,r3c2,r8c2,r8c6,r8c9,r4c9, r4c2; r6c2<>1,r4c7<>6

xy-chain: (7)r1c2-(7=8)r5c2-(8=5)r5c8-r7c8=r78c9-(5=7)r1c9; r1c2<>7

Ted
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peterj



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

PostPosted: Mon Oct 11, 2010 6:35 pm    Post subject: Reply with quote

A wing...
Quote:
m-wing(57) ; (7=5)r1c9 - r23c7=(5-7)r5c7=r5c2 ; r1c2<>7

(Same elimination as Ted's - different route)
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Marty R.



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

PostPosted: Tue Oct 12, 2010 10:26 pm    Post subject: Reply with quote

I used a typical potpourri of moves, X-Wing, W-Wing, three XY-Wings and an XY-Chain.
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