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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Thu Oct 14, 2010 1:57 am Post subject: Puzzle 10/10/14: B XY |
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I'm out of puzzles that solve with a single "wing".
| Code: | +-----------------------+
| . 1 8 | . 2 . | 7 4 6 |
| 2 . . | . . . | . 5 3 |
| 6 . 5 | 7 . . | . 2 . |
|-------+-------+-------|
| . . 6 | 8 . 3 | . 7 . |
| 3 . . | . 7 . | . . . |
| . . . | 6 . 2 | . 3 . |
|-------+-------+-------|
| 5 . . | . . . | 3 . . |
| 8 4 7 | 1 . 9 | . 6 5 |
| 1 2 . | . . . | . 9 7 |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Thu Oct 14, 2010 3:21 am Post subject: |
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Two steps...........
| Quote: | Contradiction chain: (1)r5c8-(1=4)r5c6-r5c4=r9c4-(4=8)r7c5-(8=1)r7c8: r5c8<>1
xy-wing 4-58 with extended vertex: (5=4)r9c4-(4=8)r9c7-(8=1=9=5)r234c7-r6c7=(5)r6c5; r5c4,r9c5<>5 |
Ted |
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Thu Oct 14, 2010 7:35 am Post subject: |
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How about two wings combined in a single step? An interesting "almost" wing made by combining a w-wing with an s-wing!
| Quote: | I spotted this s-wing(59) (9)r6c5=r4c5 - (9=5)r4c2 - (5)r4c7=r6c7 but it wasn't very useful.
The "almost" w-wing(48) pattern stood out... and the s-wing resolves the fin!
"almost" w-wing(48) fin (9)r6c9 ; (4=8)r9c7 - r7c8=r5c8 - (8=4)r6c9 ; r6c7<>4
fin(9)r6c9 - s-wing(59)[(9)r6c5=(5)r6c7] ; r6c7<>4
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Thu Oct 14, 2010 1:34 pm Post subject: |
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Very nice Peter 
I am getting the feeling that we are "almost" becoming comfortable with "almost" patterns. 
Ted |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Thu Oct 14, 2010 4:44 pm Post subject: |
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Interesting find Peter. As usual, I tried to find a (slightly) alternate perspective. How about a forcing chain on <9> in r6c9?
| Code: | (-9)r6c9 => W-Wing => ( -4)r6c7
(+9)r6c9 => S-Wing => (5-4)r6c7
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It's essentially the same logic, but separates the W-Wing from the S-Wing. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Oct 15, 2010 3:43 pm Post subject: |
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| Quote: | | I am getting the feeling that we are "almost" becoming comfortable with "almost" patterns. |
I'm not there yet.  
As to the puzzle:
DP (68 ) in boxes 28 forces a few eliminations
XY-Wing (594), flightless with pincer transport, r9c4<>4 |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Tue Nov 02, 2010 11:33 pm Post subject: |
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| Quote: | | It's essentially the same logic, but separates the W-Wing from the S-Wing. |
Could someone point me to a definition of the S-Wing? |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Wed Nov 03, 2010 12:56 am Post subject: |
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| Marty R. wrote: | | Could someone point me to a definition of the S-Wing? |
http://www.dailysudoku.com/sudoku/forums/viewtopic.php?p=21548&sid=e01367a1058157f30745e0c64ee65bba#21548
If you find the above a bit confusing, there's the slightly less confusing chain description:
| Code: | (X)a = (X)b - (X=Y)c - (Y)d = (Y)e => a<>Y,e<>X "a" and "e" in same house
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There's a strong link on X between cells a and b. There's a strong link on Y between cells d and e. Cell c is bivalue and equals {XY}. Cell c also sees cells b and d.
If you check the (*) cells here, you will see an excellent example of an S-Wing. (ignore the elimination on <4>.) |
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