## What is this technique called?

Advanced methods and approaches for solving Sudoku puzzles

### What is this technique called?

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:

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

What is this called, and how common is it?
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Once upon a time I was a teenager who was active on here 2007-2011
999_Springs

Posts: 367
Joined: 27 January 2007
Location: In the toilet, flushing down springs, one by one.

### Re: What is this technique called?

999_Springs wrote:
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`...|...|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]
Last edited by ronk on Sat Jul 14, 2007 8:34 pm, edited 1 time in total.
ronk
2012 Supporter

Posts: 4764
Joined: 02 November 2005
Location: Southeastern USA

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

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`# two Empty Rectangles [r2c8b6] and [r2c8b9] *-----------------------* | . . . | . . . | X . X | | - - - | - X - | - X - | | . . . | . . . | - . - | |-------+-------+-------| | . . . | . . . | - . - | | . . . | . * . | X . X | | . . . | . . . | - . - | |-------+-------+-------| | . . . | . . . | - . - | | . . . | . * . | X . X | | . . . | . . . | - . - | *-----------------------*`
daj95376
2014 Supporter

Posts: 2624
Joined: 15 May 2006

### Empty Rectangle = finned Mutant X-wing

daj95376 wrote: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 )

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

Pat

Posts: 3463
Joined: 18 July 2005