sheila08 wrote:Hmm--Simple English?
How do you learn to spot these fish??
Sheila
Merry Christmas to all...
They're not usually easy to spot, especially if you don't know one is there and if you're not filtering. Puzzles that requires finding a swordfish to solve are rated "invalid" by Pappocom software.
One way to look for them is to start from the top, look for a row that has exactly two or three of the candidate in question. When you find one, look for another row below it that also has 2 or 3 of the candidate. If all these cells are in the same three columns, look for a third row below these two. (Of course, repeat using columns.)
The swordfish concept is not quite as complex as all these posts with differing ascii styles would imply. They're just hard to spot. It's a good idea to practice on puzzles that are known to contain a swordfish. They can be hard to spot at first even when you know that it is the very next logical step.
Here are three practice puzzles containing Swordfish (when solved by typical, standard methods):
ONE
This puzzle requires only simple tactics -- and one swordfish:
- Code: Select all
. . . | . 6 . | . . 3
. . 3 | . . 9 | . 8 7
2 . . | 5 . . | . 6 .
-------+-------+------
6 . . | . 3 . | . 1 .
9 3 . | . . . | . 2 6
. 7 . | . 9 . | . . 4
-------+-------+------
. 1 . | . . 8 | . . 5
5 4 . | 6 . . | 8 . .
3 . . | . 5 . | . . .
Here's where the swordfish comes in:
- Code: Select all
. . . | . 6 . | 2 . 3
. 6 3 | . . 9 | 5 8 7
2 . . | 5 . 3 | . 6 .
-------+-------+------
6 . . | . 3 . | 9 1 8
9 3 . | . . . | 7 2 6
. 7 . | . 9 6 | 3 5 4
-------+-------+------
7 1 . | 3 . 8 | . . 5
5 4 . | 6 . . | 8 3 .
3 . . | 9 5 . | . 7 .
Here are the candidate lists where the swordfish is swimming:
- Code: Select all
148 589 1578 | 1478 6 147 | 2 49 3
14 6 3 | 124 124 9 | 5 8 7
2 89 78 | 5 478 3 | 14 6 19
-------------------+-------------------+-------------------
6 25 245 | 247 3 2457 | 9 1 8
9 3 1458 | 148 148 145 | 7 2 6
18 7 128 | 128 9 6 | 3 5 4
-------------------+-------------------+-------------------
7 1 269 | 3 24 8 | 46 49 5
5 4 29 | 6 127 127 | 8 3 129
3 28 268 | 9 5 124 | 146 7 12
Additional hints are at the bottom of this post.
===========================================================================
TWO
This puzzle requires some more harder tactics before the one swordfish:
- Code: Select all
. . . | 2 3 1 | . 5 .
. 1 . | . 8 . | . 3 .
9 . . | . . . | . . 7
-------+-------+------
. . 9 | 4 . . | 5 . .
. . 3 | 1 9 8 | 4 . .
. . 6 | . . 3 | 8 . .
-------+-------+------
4 . . | . . . | . . 5
. 9 . | . 1 . | . 4 .
. 8 . | 3 4 2 | . . .
Here's where the swordfish comes in:
- Code: Select all
. . . | 2 3 1 | 9 5 .
. 1 . | . 8 . | . 3 .
9 3 . | . . 4 | 1 . 7
-------+-------+------
8 . 9 | 4 . . | 5 1 3
. 5 3 | 1 9 8 | 4 . .
1 4 6 | . . 3 | 8 . 9
-------+-------+------
4 . 1 | . . . | 3 . 5
3 9 . | . 1 5 | . 4 .
. 8 . | 3 4 2 | . 9 1
Here are the candidate lists where the swordfish is swimming:
- Code: Select all
67 67 48 | 2 3 1 | 9 5 48
25 1 245 | 79 8 79 | 26 3 246
9 3 28 | 56 56 4 | 1 28 7
-------------------+-------------------+-------------------
8 27 9 | 4 267 67 | 5 1 3
27 5 3 | 1 9 8 | 4 267 26
1 4 6 | 57 257 3 | 8 27 9
-------------------+-------------------+-------------------
4 26 1 | 6789 67 679 | 3 268 5
3 9 27 | 68 1 5 | 267 4 268
56 8 57 | 3 4 2 | 67 9 1
Additional hints are at the bottom of this post.
===========================================================================
THREE
This puzzle requires some more harder tactics after the one swordfish:
- Code: Select all
8 . . | . 3 . | 9 2 .
. . . | . . 1 | . . 6
. 2 . | 7 . . | . . 3
-------+-------+------
. . . | . . . | 1 . 8
5 . . | 8 . 7 | . . 2
2 . 9 | . . . | . . .
-------+-------+------
1 . . | . . 3 | . 7 .
9 . . | 6 . . | . . .
. 3 7 | . 1 . | . . 4
Here's where the swordfish comes in:
- Code: Select all
8 7 . | . 3 . | 9 2 .
3 9 5 | 2 8 1 | 7 4 6
4 2 . | 7 . 9 | . . 3
-------+-------+------
7 6 4 | 3 . 2 | 1 . 8
5 1 3 | 8 . 7 | 4 . 2
2 8 9 | 1 4 . | . . 7
-------+-------+------
1 . 8 | . 2 3 | 6 7 9
9 . 2 | 6 7 . | . . .
6 3 7 | 9 1 . | 2 . 4
Here are the candidate lists where the swordfish is swimming:
- Code: Select all
8 7 16 | 45 3 456 | 9 2 15
3 9 5 | 2 8 1 | 7 4 6
4 2 16 | 7 56 9 | 58 158 3
-------------------+-------------------+-------------------
7 6 4 | 3 59 2 | 1 59 8
5 1 3 | 8 69 7 | 4 69 2
2 8 9 | 1 4 56 | 35 356 7
-------------------+-------------------+-------------------
1 45 8 | 45 2 3 | 6 7 9
9 45 2 | 6 7 458 | 358 1358 15
6 3 7 | 9 1 58 | 2 58 4
Additional hints are at the bottom of this post.
=================================================================
HINTS -- scroll down slowly so you can see just one clue at a time.
Hints for puzzle ONE:
a) The swordfish is in 2s.
b) The swordfish is in rows, eliminations in columns.
c) The swordfish is in rows 2, 6 and 7.
d) Just the 2s:
- Code: Select all
. . . | . . . | 2 . .
. . . | 2 2 . | . . .
2 . . | . . . | . . .
-------------------+-------------------+-------------------
. 2 2 | 2 . 2 | . . .
. . . | . . . | . 2 .
. . 2 | 2 . . | . . .
-------------------+-------------------+-------------------
. . 2 | . 2 . | . . .
. . 2 | . 2 2 | . . 2
. 2 2 | . . 2 | . . 2
e) The swordfish marked with '+', the eliminations marked with '-':
[EDIT: nasty typo fixed. Sorry about that.]- Code: Select all
. . . | . . . | 2 . .
. . . |+2 +2 . | . . .
2 . . | . . . | . . .
-------------------+-------------------+-------------------
. 2 -2 |-2 . 2 | . . .
. . . | . . . | . 2 .
. . +2 |+2 . . | . . .
-------------------+-------------------+-------------------
. . +2 | . +2 . | . . .
. . -2 | . -2 2 | . . 2
. 2 -2 | . . 2 | . . 2
Hints for puzzle TWO:
a) The swordfish is in 2s.
b) The swordfish is in rows, eliminations in columns.
c) The swordfish is in rows 4, 6 and 7.
Hints for puzzle THREE:
a) The swordfish is in 5s.
b) The swordfish is in columns, eliminations in rows.
c) The swordfish is in columns 2, 4 and 9.