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Puzzle 10/08/18: C

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Wed Aug 18, 2010 5:24 am    Post subject: Puzzle 10/08/18: C Reply with quote

Code:
 +-----------------------+
 | 4 . . | . . 5 | . 7 . |
 | . 6 9 | . . . | . 5 . |
 | . 7 . | 9 . . | 2 . 6 |
 |-------+-------+-------|
 | . . 8 | 5 . 2 | . . . |
 | . . . | . . 6 | . 8 . |
 | 6 . . | 8 9 3 | . . 7 |
 |-------+-------+-------|
 | . . 5 | . . . | 7 . 2 |
 | 2 9 . | . 5 . | . . 1 |
 | . . 6 | . . 9 | 8 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: Wed Aug 18, 2010 8:41 am    Post subject: Reply with quote

Almost a BBDB for me, and I stared at the grid for some time for the opening play!
Quote:
xyz-wing(34-1) r4c2 ; r56c2<>1
skyscraper(1) ; r12c7<>1, r4c8<>1
xy-wing(38-1) r7c1 ; r1c2<>1, r9c1<>1
xy-chain (1=8)r2c1 - (8=3)r7c1 - (3=7)r9c1 - (7=4)r8c3 - (4=1)r6c3 ; r45c1<>1
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JC Van Hay



Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium

PostPosted: Wed Aug 18, 2010 10:31 am    Post subject: Reply with quote

A 12-SIS solution ...
Quote:
4-SIS AIC : 1R9 7B7 4C3 1C3 : => r1c2<>1
4-SIS AIC : 2C2 8C2 4B7 7C3 : => r5c3<>2
4-SIS AIC : UR(23)r29c45 : [(7)r9c45,(1)r2c45] 1B1 (14)R63 (47)R8C3 : => r8c4<>7
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JC Van Hay



Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium

PostPosted: Wed Aug 18, 2010 12:20 pm    Post subject: Reply with quote

A 10-SIS proof, in the same line of thought as the previous one ...
Quote:
3-SIS AIC : (13)R9C2 (38)R7C1 8C2 : => r1c2<>1
4-SIS AIC : 2C2 8C2 4B7 7C3 : => r5c3<>2
4-SIS AIC : 1B1 8R2 4R2 4R6 : => r6c3<>1
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tlanglet



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

PostPosted: Wed Aug 18, 2010 1:22 pm    Post subject: Reply with quote

Three steps..................

Quote:
ANP(2=13)r13c3-(1=4)r6c3-(4=7)r8c3-(7=13)r9c12-(3=8)r7c1-(8=13)r2c1; r13c3<>13=2

skyscraper (1)r36c3; r12c7,r4c7<>1

xy-wing -138 vertex (38)r7c1; r1c2,r9c1<>1

Ted
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Wed Aug 18, 2010 3:30 pm    Post subject: Reply with quote

Well, it looks like this puzzle was a hit! _ Very Happy _
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tlanglet



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

PostPosted: Wed Aug 18, 2010 4:56 pm    Post subject: Reply with quote

daj95376 wrote:
Well, it looks like this puzzle was a hit! _ Very Happy _


Yes Danny, it and all your other puzzles have been very enjoyable. I especially like puzzles that result in noticeably different solutions paths/steps since they offer me opportunities to study other complex techniques.

Thanks as always for you time and energy.

Ted Very Happy
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peterj



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

PostPosted: Wed Aug 18, 2010 5:39 pm    Post subject: Reply with quote

Ted, seconded.
Danny, thanks!
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Marty R.



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

PostPosted: Fri Aug 20, 2010 1:22 am    Post subject: Reply with quote

Looking at the implications of the potential DP 36 in boxes 28, the DP killers force some common eliminations. That set up a puzzle-ending XY-Wing on 138.
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