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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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 Posted: Sat Jul 26, 2008 2:58 am Post subject: LA Times/Freep - July 25, 2008 |
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| Code: | +-------+-------+-------+
| . 8 . | . 9 . | . . . |
| . 3 . | . . . | . . 4 |
| . . . | . 8 6 | 2 . . |
+-------+-------+-------+
| . . . | . 1 . | . 7 . |
| 3 . . | 4 . 9 | . . 1 |
| . 4 . | . . . | . . . |
+-------+-------+-------+
| . . 6 | 1 7 . | . . . |
| 8 . . | . . . | . 5 2 |
| . . . | . . . | . 8 . |
+-------+-------+-------+ |
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Sat Jul 26, 2008 11:57 am Post subject: |
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Two overlapping type 6 (or hidden) UR's leave 1 in r1c3.
And then - lets try to find a finned xy-wing.
| Code: | *--------------------------------------------------*
|#27 8 1 | 27 9 4 | 6 3 5 |
| 6 3 27 | 257 *25 1 | 8 9 4 |
| 49 5 49 | 3 8 6 | 2 1 7 |
|----------------+----------------+----------------|
|-29 6 259 | 8 1 *25 | 4 7 3 |
| 3 7 8 | 4 26 9 | 5 26 1 |
| 1 4 25 | 256 3 7 | 9 26 8 |
|----------------+----------------+----------------|
| 5 2 6 | 1 7 8 | 3 4 9 |
| 8 19 47 | 69 46 3 | 17 5 2 |
|#47 19 3 | 259 #245 25 | 17 8 6 |
*--------------------------------------------------* |
Either the fin r9c5=5 or (xy-wing 247) one of r1c1 and r9c5 is 2.
r9c5=5 => r2c5=2 => r1c1=2.
r9c5=2 => r4c6=2.
So we can eliminate 2 from r4c1.
[Edit: corrected typo]
Last edited by ravel on Sat Jul 26, 2008 8:05 pm; edited 1 time in total |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Sat Jul 26, 2008 1:01 pm Post subject: |
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| I see the Type 6 UR using 27 - but I have 127 in R1C3 - so I'm left with a 12 not a 1. I must have missed something in basics though I can't see what. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Jul 26, 2008 3:33 pm Post subject: |
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| cgordon wrote: | | I see the Type 6 UR using 27 - but I have 127 in R1C3 - so I'm left with a 12 not a 1. I must have missed something in basics though I can't see what. |
Craig,
Because 7 is a strong link in row 2, 7 can be eliminated from r1c3 to break up a deadly pattern. That exposes a true Type 6 UR on 12, forcing r1c3 and r1c6 to both be 1.
After that I couldn't find anything and used Medusa traps to finish it off. |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Sat Jul 26, 2008 9:43 pm Post subject: |
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I find that XY Chains (as well as Type 1, and sometimes Type 4, URs) are frequently useful in these LAT/Freep puzzles. In this case, the 4-cell chain
(2=7)r2c3 - (7=4)r8c3 - (4=6)r8c5 - (6=2)r5c5
removes <2> from r2c5 and converts that UR to a simple Type 1.
Meanwhile, as the recent posted examples have shown, these "Finned XY Wing" things are surely versatile in their possible inner workings! I like them because they allow one to find what are essentially unidirectional AICs that would otherwise be very obscure to discover. |
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