The New Sudoku Players' Forum

[bat999]

Hi
I saw a blog post that said something like...
"by the way, do you know that Swordfish can use boxes? Not just rows and columns"

I can't find the post now.

Does anybody here know about this technique?

If it's true, please explain and show an example.

Or provide a link to some internet documentation about it.

[JasonLion]

There is a swordfish like pattern that uses blocks instead of some/all of the rows/columns, but it is not called a swordfish.

Lookup MutantFish, for example here. The logic is essentially the same as for a swordfish, but they are a fair bit harder to spot in a puzzle.

[Leren]

Hi bat. Fish that use boxes as well as rows and columns are known as Franken or Mutant. You can learn all about Fish on this site here http://forum.enjoysudoku.com/the-ultimate-fish-guide-t4993.html known as the ultimate fish guide
but, as like many other topics on this site, it's a hard slog through a very extensive topic. An easier way is to type franken or mutant in the search box, and you'll see discussion of examples or discussion as they come up in daily puzzles and so on, perhaps a more easy way to digest the information a bit at a time. Here is a link to the Hodoku site that has a fairly basic coverage of the topic, but it has graphical worked examples and may be useful.

http://hodoku.sourceforge.net/en/tech_fishc.php

Leren

[bat999]

OK, thanks.
Not so straightforward, what!

[rjamil]

Hi,

While I am reading Swordfish technique for learning/understanding, found this site.

Here Swordfish example given for candidate 3 in Examples B. stated that, "We can eliminate 3 as candidate in every cell marked in blue." (Where only rows marked in blue.)

In Example C, stated that, "In any case, each of the rows 2, 4, 6 and 8, must contain a 3 in one of the colored cells, so no other cell in those rows can contain a 3." (But the same condition also applies to columns 2, 4, 6 and 8 too.)

My question is, why eliminate candidate 3 from rows 2, 4, 6 and 8 only? Why not from columns 2, 4, 6 and 8 as well?

Edit: get it.
From here, as stated, "When 2 Rows contain only 2 candidates each, and candidates are located in the Same two columns, you may eliminate all other candidates from these 2 columns."

Similarly, when 2 columns contain only 2 candidates each, and candidates are located in the same two rows, you may eliminate all other candidates from these 2 rows.

R. Jamil