The New Sudoku Players' Forum

[999_Springs]

I haven't been posting for a while because I have had exams and I have also been away for some time. Anyway, I'm back, and while I was away I found this technique. I wouldn't call it "new" because there seem to be hundreds of fish experts who came to these forums earlier than I did, so it is certain they have found it already.

Suppose you have two columns in the same 3x9 block and they have the same three places for a particular candidate. Now add to that a strong link, one end of which sees a candidate in each of these two columns, thus:

Code: Select all

...|...|X.X
...|.X--+X.
...|...||.|
---+---+|-|
...|...||.|
...|.*.|X.X
---+---+|-|
...|...||.|
...|.*.|X.X

Possibilities in the places with asterisks may be eliminated.

What is this called, and how common is it?

[ronk]

Code: Select all

...|...|X.X
...|.X--+X.
...|...||.|
---+---+|-|
...|...||.|
...|.*.|X.X
...|...||.|
---+---+|-|
...|...||.|
...|.*.|X.X
...|...||.|
Possibilities in the places with asterisks may be eliminated.

What is this called, and how common is it?

To be consistent with The Ultimate FISH Guide, it would be called a sashimi mutant swordfish (r2c79\r58b3 plus fin r2c5). No idea how common it might be. [edit: added link]

[daj95376]

The initial layout seemed to be shy on cells. After filling in, I see ...

Code: Select all

# two Empty Rectangles [r2c8b6] and [r2c8b9]
 *-----------------------*
 | . . . | . . . | X . X |
 | - - - | - X - | - X - |
 | . . . | . . . | - . - |
 |-------+-------+-------|
 | . . . | . . . | - . - |
 | . . . | . * . | X . X |
 | . . . | . . . | - . - |
 |-------+-------+-------|
 | . . . | . . . | - . - |
 | . . . | . * . | X . X |
 | . . . | . . . | - . - |
 *-----------------------*


[Pat]

two Empty Rectangles -- r2c8b6 and r2c8b9

thanks, daj95376, that reduces it to fish of order 2

( with the same fin at r2c5 )

• r2b6\r5c8
• r2b9\r8c8

( the information about r3c79 isn't needed )

Code: Select all

 *-----------------------*
 | . . . | . . . | . . . |
 | / / / | / # / | / X / |
 | . . . | . . . | . . . |
 |-------+-------+-------|
 | . . . | . . . | / X / |
 | . . . | . * . | X X X |
 | . . . | . . . | / X / |
 |-------+-------+-------|