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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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 Posted: Sat Sep 16, 2006 12:22 pm Post subject: DB Saturday Puzzle - September 16, 2006 |
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Puzzle: DB091606 ******
| Code: | +-------+-------+-------+
| 6 2 . | . 7 4 | 9 . . |
| . . 7 | . . 9 | . . . |
| 3 . 4 | . . . | 2 1 . |
+-------+-------+-------+
| . . . | . 4 5 | . . . |
| 9 . 3 | . . . | 5 . 4 |
| . . . | 9 1 . | . . . |
+-------+-------+-------+
| . 8 6 | . . . | 3 . 1 |
| . . . | 5 . . | 6 . . |
| . . 1 | 8 6 . | . 5 9 |
+-------+-------+-------+ |
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Sep 16, 2006 4:57 pm Post subject: |
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This puzzle allowed a fair number of cells to be solved early on. A Finned X-Wing and a breakup of a deadly pattern were of little help and I reached a position, which I posted, at which the only solution for me was a chain. However, while studying my post I noticed I had missed a couple of locked candidates--excuse me, box-line interactions  --so I deleted my post and eliminated some more candidates. Now an XY-Wing was exposed, that solved a cell and everything opened up. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Sep 16, 2006 5:53 pm Post subject: Another solution |
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I got it to here:
| Code: | +----------------+----------------+----------------+
| 6 2 8 | 1 7 4 | 9 3 5 |
| 1 5 7 | 23b 23B 9 | 48 468 68 |
| 3 9 4 | 6 5 8 | 2 1 7 |
+----------------+----------------+----------------+
| 78 67 2 | 37 4 5 | 1 9 368 |
| 9 1 3 | 27B 8 26 | 5 267# 4 |
| 478 467 5 | 9 1 236 | 78 2678 2368 |
+----------------+----------------+----------------+
| 5 8 6 | 4 9 27a | 3 27A 1 |
| 247 347 9 | 5 23b 1 | 6 2478 28 |
| 247 347 1 | 8 6 237 | 47 5 9 |
+----------------+----------------+----------------+ |
Marty, I presume your finned X-wing is in there somewhere. If so, can you point it out?
I used strong links (multi-coloring) on <2>. There are two chains of strong links, connected by a weak link in box 8. Using the same logic as a fork, at least one of A and B must be <2>. So, R5C8 (#) cannot be <2>.
A line-box interaction then gets you to here:
| Code: | +----------------+----------------+----------------+
| 6 2 8 | 1 7 4 | 9 3 5 |
| 1 5 7 | 23 23 9 | 48 468 68 |
| 3 9 4 | 6 5 8 | 2 1 7 |
+----------------+----------------+----------------+
| 78 67 2 | 37 4 5 | 1 9 368 |
| 9 1 3 | 27 8 26 | 5 67 4 |
| 478 467 5 | 9 1 36 | 78 2678 2368 |
+----------------+----------------+----------------+
| 5 8 6 | 4 9 27 | 3 27 1 |
| 247 347 9 | 5 23 1 | 6 2478 28 |
| 247 347 1 | 8 6 237 | 47 5 9 |
+----------------+----------------+----------------+ |
There are three XY-wings to choose from.
Two of them are in R57C68. The first (26, 67, 27) eliminates <2> in R7C6. The second (27, 26, 67) eliminates <7> in R7C8. This is a (sort of trivial) example of overlapping wings, where the candidate elimination of one wing destroys the other wing.
Keith |
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Sat Sep 16, 2006 7:13 pm Post subject: |
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I'll attempt to answer, maybe Marty saw a different one.
X-wing in r67c68 with fin in r6c9.
Makes the same exclusion as the multi-colouring you used. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Sep 16, 2006 9:08 pm Post subject: |
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| I don't know if my finned wing was the same as Tracy's, but I do know that it was on "2." |
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