Hard Puzzle question

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Hard Puzzle question

Postby Cabby » Sat Feb 11, 2006 8:15 am

Hi,
While reading the reply to a previous post from Marjorie, I became confused with part of the answer. Could someone elaborate.

Tia,

Cabby
*-----------------------------------------------------------------*
| 2 -359 359 | 8 349 3479 | 347 6 1 |
| 68 1 368 | 47 5 2347 | 23478 9 237 |
| 7 *4 #389 |*29 1 6 | 238 5 23 |
|---------------------+---------------------+---------------------|
| 3 *279 4 |*29 8 1 | 5 27 6 |
| 689 279 6789 | 5 349 2349 | 1 2378 237 |
| 58 25 1 | 6 7 23 | 9 238 4 |
|---------------------+---------------------+---------------------|
| 4 8 257 | 3 6 57 | 27 1 9 |
| 59 3579 3579 | 1 2 579 | 6 4 8 |
| 1 6 279 | 47 49 8 | 237 237 5 |
*-----------------------------------------------------------------*
Eliminating 9 From r1c2 (Finned XWing in rows 3 & 4) ---- or SASHIMI Xwing
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Postby tarek » Sat Feb 11, 2006 10:56 am

Hi Cabby,

This is actually an advanced technique, you can also reach the same conclusion using what is called a turbot fish.

for an understanding of FINNED fishy techniques, you have to read the Filet-O-Fish principle posted in the advanced techniques forum.

Tarek
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Postby QBasicMac » Sat Feb 11, 2006 9:36 pm

Otherwise, if you want to have the fun of trying 3 easy puzzles, do this:

Beginning here

Code: Select all
+------------------+----------------+------------------+
| 2    359   359   | 8    349  3479 | 347    6     1   |
| 68   1     368   | 247  5    2347 | 23478  9     237 |
| 7    4     389   | 29   1    6    | 238    5     23  |
+------------------+----------------+------------------+
| 3    279   4     | 29   8    1    | 5      27    6   |
| 689  279   26789 | 5    349  2349 | 1      2378  237 |
| 58   25    1     | 6    7    23   | 9      238   4   |
+------------------+----------------+------------------+
| 4    8     257   | 3    6    57   | 27     1     9   |
| 59   3579  3579  | 1    2    579  | 6      4     8   |
| 1    6     2379  | 479  49   8    | 237    237   5   |
+------------------+----------------+------------------+


Do eliminations for
Locked candidate 2 in box 7
Locked candidate 3 in box 9
Naked pair 29 in col 4

Then make two more copies of the result and

1) Place 2 in cell r9c8 - try to solve
2) Place 3 in cell r9c8 - try to solve
3) Place 7 in cell r9c8 - try to solve

Two of them will not solve. One will. Thus the puzzle is valid and you have found the only solution.

Mac
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Postby vidarino » Sat Feb 11, 2006 11:37 pm

QBasicMac wrote:Then make two more copies of the result and ...


Hmm, isn't it more rewarding to actually try to deduce the next logical move instead of resorting to blind trial and error? I certainly think it is. I'm not knocking T&E, though, but for me the whole point of solving a puzzle is exactly that; solving it, not doing an exhaustive search to verify that it only has one solution. ;)

Anyway, it's just a game, and the point is to have fun, so if it works for you, knock yourself out.:)

Vidar
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