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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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 Posted: Wed Apr 02, 2008 5:37 pm Post subject: FSF |
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M1115024 (122)
| Code: |
+-------+-------+-------+
| . . . | . . 2 | . . . |
| 3 . 7 | 6 . . | 1 . 4 |
| . . 6 | . 3 . | 9 . . |
+-------+-------+-------+
| . 4 . | . 2 . | . . 7 |
| . 8 . | 9 . 4 | . 1 . |
| 1 . . | . 5 . | . 4 . |
+-------+-------+-------+
| . . 5 | . 4 . | 7 . . |
| 6 . 8 | 3 . . | 4 . 9 |
| . . . | . . 6 | . . . |
+-------+-------+-------+
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Play this puzzle online
There's a well-known but somewhat maligned creature hiding in here. Have a go if you want to try to find it, or some other method, before I reveal all.
-----------------------------------------------------------------------------------
Here's the grid after basics, the X-wing, and some UR eliminations:
| Code: |
+------------+----------------+-----------------+
| 489 159 14 | 1458 1789 2 | 358 35678 3568 |
| 3 259 7 | 6 89 589 | 1 258 4 |
| 248 15 6 | 1458* 3 1578*| 9 578 258 |
+------------+----------------+-----------------+
| 5 4 3 | 18* 2 18* | 6 9 7 |
| 7 8 2 | 9 6 4 | 35 1 35 |
| 1 6 9 | 7 5 3 | 28 4 28 |
+------------+----------------+-----------------+
| 29 13 5 | -128 4 -189 | 7 368 1368 |
| 6 127 8 | 3 17# 157# | 4 25 9 |
| 249 379 14 | -1258 1789 6 | 2358 358 1235 |
+------------+----------------+-----------------+
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This is about 1s. Note the effect of trying 1 in each of the c3 14s. (I was vaguely looking for an ER-type position.) If the top 1 is true, then the *s in r3 are true - I've added *s to the 18s to show that we now have an X-wing. Alternatively, if the bottom 1 is true, then the #s are true. Familiar territory: either *s or #s are true, so that we can eliminate the 1s in c46, box 8.
Having thought about it, I've realised that I'd found a finned swordfish - r348, with the fin in r8c5. It's not too easy to see the logic if you try a 1 in each of the 18s, but if you try 1 & not-1 in r3c2, you get the same position as above. Don't fancy my chances of finding one of these things again - I find the logic for swordfish, finned or not, easy if there are just two candidates in each arm, but less obvious when, as here, one or more arm has 3 candidates.
(There's a further tiny detail. I'd already removed a 1 in r9c2 - UR in 17s. Better in fact to delay that, for now you can eliminate the 3 in r7c9 - UR in 13s, and THEN do r9c2) |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Thu Apr 03, 2008 7:44 am Post subject: |
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You can also see those <1> eliminations as a Finned X-Wing in r34 with the otherwise useless remote Fin transported to r9c3 and r7c9.
While it is "tidiest" as a Finned Swordfish, the Finned X-Wing is probably easier for most to spot. It is worthwhile to check for transportation options in such cases. |
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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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| Posted: Thu Apr 03, 2008 12:57 pm Post subject: |
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| Thanks. I didn't really understand the idea of transporting x-wing fins: now I do (I think). |
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Thu Apr 03, 2008 6:24 pm Post subject: |
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Nice application of transports.
After that i saw a useless, but interesting elimination.
| Code: | *--------------------------------------------------------------------*
| 489 159 14 | 145 1789 2 | 358 35678 3568 |
| 3 259 7 | 6 89 59 | 1 258 4 |
| 248 15 6 | 145 3 157 | 9 578 258 |
|----------------------+----------------------+----------------------|
| 5 4 3 | 18 2 18 | 6 9 7 |
| 7 8 2 | 9 6 4 | 35 1 35 |
| 1 6 9 | 7 5 3 | 28 4 28 |
|----------------------+----------------------+----------------------|
| 29 13 5 | 28 4 89 | 7 36 136 |
| 6 127 8 | 3 17 157 | 4 #25 9 |
|-249 379 14 |#25 179 6 |*2358 *358 *12358 |
*--------------------------------------------------------------------*
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Looking at the 25 pairs:
r9c4=2 => r9c789<>2 => r8c8=2
r9c4=5 => r9c789<>5 => r8c8=5
So the pairs must have the same value and 25 is locked to r9c4 and r9c789 (e.g. if r9c4=2, then r8c8=2 and one of r9c789 must be 5).
This eliminates 2 in r9c1.
To solve it, i used a 4-cell xy-chain between r9c4 and r2c6, one of them must be 5. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Apr 04, 2008 12:14 am Post subject: |
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| Would someone like to give me a brief explanation on transporting an X-Wing fin? |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Sat Apr 05, 2008 12:50 am Post subject: |
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| Marty R. wrote: | | Would someone like to give me a brief explanation on transporting an X-Wing fin? |
I'll give it a go. But first, a refresher:
In a finned fish, any candidate that would be eliminated if the fish were true and if the fin were true can be eliminated due to the finned fish.
Transporting a fin (or a pincer in a wing) is the same as "extended" coloring: any candidate which must be true if the fin is true can serve as a transported fin. And, the transportation can be repeated: any candidate which must be true if a transported fin is true can also serve as a transported fin.
So, in the puzzle above, the <1> in r3c2 is the (remote) fin. If it were true, then the <1> in r9c3 must also be true and is thus a transported fin. Since the <1> in r9c4 "sees" both this transported fin and the r34 X-Wing, it is eliminated.
But also, if the transported fin at r9c3 is true, then the <1> at r7c9 must be true. So it, too, is a transported fin, eliminating the <1>s in r7c46. |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Sat Apr 05, 2008 1:03 am Post subject: |
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Ravel,
Your interesting elimination can be seen, slightly differently, as a Sue de Coq. The 6 digits {123568} are confined to the 6 cells r7c89|r9c4789 with <8> locked in r9c789, and a {136} locked set in r7c89|r9c789 overlapping with a {25} locked set in r9c4789. It would eliminate <1>, <3> and <6> in any other cell in b9 and <2>, <5> and <8> in any other cell in r9. The only such elimination is that <2> in r9c1.
By the way... since those {25}s are a complementary pair, there is an extended M-Wing that also eliminates that <2> based on the strongly linked <2>s in c8, r2 and c2 (or b1). |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sun Apr 06, 2008 3:52 am Post subject: |
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| Quote: | | I'll give it a go. |
Thank you. But there are so many things here that I don't understand, I'm reluctant to interrogate you once again. I'll let it marinate and may come back to it. |
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