Sashimi

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zoltag
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Sashimi

Post by zoltag »

This general pattern is interesting and mingles somewhat with grouped x patterns when the sashimi part is in one box, finned or not. I have seen cases where Sudoku Cue misses eliminations that are there. Here is the general case that I mean.


I see a sashimi sword

Code: Select all

1 / / | . / 1 | / / /
. . . | . . . | . . .
. . . | . . . | . . .
---------------------
. . . | # ? 1 | . . .
. . . | # ? # | . . .
. . . | 1 ? # | . . .
---------------------
. . . | . . . | . . .
. . . | . . . | . . .
1 / / | 1 / . | / / /
My observation is that SQ misses the eliminations denoted by the "/" symbols.
The "#" symbol denotes fins that need not be there, but may be.
SQ also misses some exclusions marked by the "?".

Here is an actual position.

Code: Select all

.---------------.---------------.---------------.
| 34   1    3469| 8    5  -369  | 39   2    7   |
| 5    69   7   | 2   *36 -3169 | 1349 34   8   |
| 8    2    39  |*13   7    4   | 139  5    6   |
:---------------+---------------+---------------:
| 1    5    23  | 7    4    23  | 6    8    9   |
| 7    69   69  | 5    1    8   | 2    34   34  |
|-324 *34   8   |*36   9   -326 | 5    7    1   |
:---------------+---------------+---------------:
| 234  7    1234| 9    8    13  | 34   6    5   |
| 9   *34   5   |*346 *36   7   | 8    1    2   |
| 6    8    134 | 14   2    5   | 7    9    34  |
'---------------'---------------'---------------'

Here in Box 2 the 3s in c45 own the box but have no impact on any rows.
Thus 3 should be removed from r12c6. If they were finned, still, remove
3s from c6 in box2.

The general case of a disjoint fish where the fracture is in one box leaves the
pattern able to eliminate much like an x-wing or regular sword for the parts
not involved in the box. The box has no external affect.

Sudoku Cue misses, in this case, 3 of the 4 exclusions, r2c6 r6c16.

Edited to add the original puzzle:

Code: Select all

. 1 . | 8 . . | . 2 7
5 . 7 | 2 . . | . . 8
. 2 . | . . 4 | . . .
---------------------
1 5 . | . 4 . | 6 . .
. . . | 5 . 8 | . . .
. . 8 | . 9 . | . 7 1
---------------------
. . . | 9 . . | . 6 .
9 . . | . . 7 | 8 . 2
6 8 . | . . 5 | . 9 .
Edited to add;"in box2".
zoltag
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Ping

Post by zoltag »

I don't mind being shown wrong.

Ruud, did you look at this?
zoltag
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Post by zoltag »

I don't mind being shown to be correct, either! :)

http://www.setbb.com/phpbb/viewtopic.php?p=7370#7370
zoltag
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Post by zoltag »

And the lack of response suggests this link. :)

http://www.answers.com/topic/hidebound
Last edited by zoltag on Thu Feb 08, 2007 4:25 am, edited 1 time in total.
Ruud
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Post by Ruud »

Zoltag, Havard once introduced the "Extended Skyscraper" technique on the Pappocom forum. I never implemented it in SudoCue, but it looks like you have a similar pattern. There are 2 intertwined finned Swordfishes.

One of the things on the SudoCue todo list is an exhaustive search for all possible steps in the (current) grid. Such a search should at least show the 2 fishes.

Ruud
“If the human brain were so simple that we could understand it, we would be so simple that we couldn't.” - Emerson M Pugh
zoltag
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Post by zoltag »

Thanks Ruud!
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