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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Tue Jul 06, 2010 8:34 pm Post subject: Puzzle 10/07/06: XY |
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| Code: | +-----------------------+
| 2 6 . | . 9 4 | 5 . . |
| 9 . . | 6 . 5 | . 2 . |
| . . . | . . . | 6 . . |
|-------+-------+-------|
| . 1 . | 5 . . | 8 . 4 |
| 5 . . | . . . | 9 . . |
| 4 3 . | . . 9 | . . . |
|-------+-------+-------|
| 7 . 8 | 9 1 . | . . 5 |
| . 5 . | . . . | . . . |
| . . . | 4 . . | 3 . 2 |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site
| Code: | after basics
+--------------------------------------------------------------+
| 2 6 13 | 78 9 4 | 5 1378 1378 |
| 9 4 13 | 6 78 5 | 17 2 1378 |
| 8 7 5 | 123 23 12 | 6 4 9 |
|--------------------+--------------------+--------------------|
| 6 1 9 | 5 237 27 | 8 37 4 |
| 5 8 2 | 137 4 167 | 9 137 1367 |
| 4 3 7 | 18 68 9 | 2 5 16 |
|--------------------+--------------------+--------------------|
| 7 2 8 | 9 1 3 | 4 6 5 |
| 3 5 4 | 27 267 2678 | 17 9 178 |
| 1 9 6 | 4 5 78 | 3 78 2 |
+--------------------------------------------------------------+
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Wed Jul 07, 2010 12:42 pm Post subject: |
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| Quote: | Finned X-Wing (7), which I think was useless
UR (13) in boxes 13. R12c9 must be 7 or 8; either one solves box 8 |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Wed Jul 07, 2010 1:03 pm Post subject: |
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Two steps.............
| Quote: | Almost xy-wing 6-78 with vertex (68)r6c5, pincer (78)r2c5, pincer (67)r5c6 and fin (1)r5c6
If xy-wing is true: r4c5<>7
If fin is true: (1)r5c6-(1=2)r3c6-(2=7)r4c6; r4c5<>7
x-wing 7 r49c68; r58c6,r15c8<>7
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Ted |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Wed Jul 07, 2010 1:10 pm Post subject: |
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| Marty R. wrote: | | Quote: | Finned X-Wing (7), which I think was useless
UR (13) in boxes 13. R12c9 must be 7 or 8; either one solves box 8 |
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Marty, that was a very nice find. I orginally looked at that situation also but did not find a solution. However after reading your post, I looked at it again and found it.
Ted |
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dejsmith
Joined: 23 Oct 2005
Posts: 42
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| Posted: Thu Jul 08, 2010 3:29 am Post subject: |
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Here is a different course, if it is valid to extend a W Wing. W Wing (78) with strong link (7) in C7. Extending both ends eliminates 8 in R1C9. That opens up an XYZ Wing (137), which eliminates (1) in R1C8. And the puzzle solves.
Is that valid? I hesitate to even suggest it because if it hasn't been discussed by the time I get to it, something must be wrong.
Dave |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Jul 08, 2010 3:48 am Post subject: |
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| dejsmith wrote: | Here is a different course, if it is valid to extend a W Wing. W Wing (7 with strong link (7) in C7. Extending both ends eliminates 8 in R1C9. That opens up an XYZ Wing (137), which eliminates (1) in R1C8. And the puzzle solves.
Is that valid? I hesitate to even suggest it because if it hasn't been discussed by the time I get to it, something must be wrong.
Dave |
Basically, it's valid to extend pincers in any technique where there are pincers. You just have to show that the existence of a value in a pincer cell proves the same value in another cell. (I hope I said that correctly). |
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