Why isn't this a finned swordfish?

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Why isn't this a finned swordfish?

Postby JeJ » Thu Mar 17, 2011 3:35 pm

I was playing this puzzle:
Code: Select all
.-----------------.--------------------.-------------.
| 278    35  9    | 25     2578  4     | 23  16   16 |
| 12678  28  1278 | 126    3     12678 | 9   5    4  |
| 126    35  4    | 12569  2569  1256  | 23  8    7  |
:-----------------+--------------------+-------------:
| 9      6   12   | 8      4     12    | 7   3    5  |
| 128    28  5    | 7      26    3     | 4   16   9  |
| 4      7   3    | 156    56    9     | 8   2    16 |
:-----------------+--------------------+-------------:
| 5      1   278  | 249    2789  278   | 6   479  3  |
| 3      9   6    | 24     1     278   | 5   47   28 |
| 278    4   278  | 3      569   56    | 1   79   28 |
'-----------------'--------------------'-------------'

And thought that when looking at "1's", rows 3, 4 and 6 formed a finned swordfish with the fin being at r4c3, but if it were true, I could eliminate the "1" from r5c1 and that gives me an error. So why aren't these 3 rows a finned swordfish?
JeJ
 
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Re: Why isn't this a finned swordfish?

Postby JasonLion » Thu Mar 17, 2011 6:34 pm

Looking at just the pencil marks for 1, we have:
Code: Select all
. . . | . . . | . 1 1
1 . 1 | 1 . 1 | . . .
1 . . | 1 . 1 | . . .
------+-------+------
. . 1 | . . 1 | . . .
1 . . | . . . | . 1 .
. . . | 1 . . | . . 1
------+-------+------
. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
A finned swordfish, ignoring the fin cells, should have 1s in exactly three rows and three columns. But even ignoring R4C3, rows 3, 4, & 6 have 1s in four columns (1, 4, 6, & 9).
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Re: Why isn't this a finned swordfish?

Postby PIsaacson » Thu Mar 17, 2011 6:43 pm

JeJ,

I see a finned X-Wing c36\r24 fin at r3c6 with the exclusion r2c4 <> 1. I don't see how you could build a valid cover set with your proposed r346 base sets unless you use something like a finned franken fish. The only thing I could come up with for the r2c4 <> 1 elimination was c3b5\r24c4, but that's still an X-Wing instead of swordfish variety and it doesn't include all of your proposed base sets. I think the 1r6c9 candidate is the show stopper here, but I'm not an expert fisherman by any stretch of the imagination, so perhaps someone else has a valid cover set with eliminations for the r346 base set.

Cheers,
Paul
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Re: Why isn't this a finned swordfish?

Postby JeJ » Thu Mar 17, 2011 7:42 pm

You two are right, I didn't see the "1" on c9
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