Solver App for Android and iPhone
Strategies for Number Puzzles of all kinds
Page Index
Basic Strategies
Tough Strategies
Diabolical Strategies
Extreme Strategies
Deprecated Strategies
Order Str8ts Book 1
Order Now! Order Str8ts Book 2
Order Now!

Finned Swordfish

Finned SwordFish Example 1
Finned SwordFish Example 1 : Load Example or : From the Start
This is a particularly extreme Sudoku puzzle but the Finned Swordfish is nicely arranged. As discussed in the article on SwordFish it is not necessary for every cell in the 3 by 3 formation to contain the candidate, in this example candidate 3. This SwordFish is a 2-2-3 version since we have 3 twice in the first column, twice in the second column and three times in the third column. It is orientated on the columns since they are the units where candidate 3 occurs at least three times but no more. We are eliminating in the rows.

Now, that said it is not a perfect Swordfish because the centre column 5 contains an extra 3 in J5, which ruins the whole formation. However, the Finned Rule says we can ignore it if we confine the eliminations to the box where the fin is, namely box 8. There is one 3 that we can remove, on G4.

Finned Sashimi Example 1
Finned Sashimi Example 1 : Load Example or : From the Start

Two examples now of the Sashimi variety of Finned SwordFishies.

Figure two is a little more bunched up but we have a 2-2-3 formation based on eliminations in rows. The exceptional candidate 3 which blocks this from being a perfect SwordFish is on G2. But we can invoke the Sashimi observation to ignore the lack of a 3 on H2, one of the corners of the SwordFish. Eliminating in row H and box 7 we an remove the 3 from H1.

Finned Sashimi Example 2
Finned Sashimi Example 2 : Load Example or : From the Start

The second example illustrates that the Sashimi cell doesn't have to be a clue or a solved cell. The brown cell A6 simply lacks the candidate 7, which had been removed using previous logical strategies. The double fin is in green, A4 and A5. This is quite a restricted SwordFish, which in row orientation is a 1-2-2 formation - but it works!
Here is a lovely Sudoku made by Klaus Brenner (April 2012).
Try loading this one. It contains
  • 1 X-Wing on 6
  • 1 Finned-X-Wing on 6
  • 1 Swordfish on 9
  • 1 Finned Swordfish on 6, brown cell H9 never contained a 6
  • 1 Finned Sashimi Swordfish on 6, brown cell G8 never contained a 6

Go back to Finned X-WingContinue to Franken Sword Fish


Your Name/Handle

Email Address - required for confirmation (it will not be displayed here)

Your comment or question

Please enter the
letters you see:
Enter these letters Remember me

Please keep your comments relevant to this article.
Email addresses are never displayed, but they are required to confirm your comments. When you enter your name and email address, you'll be sent a link to confirm your comment. Line breaks and paragraphs are automatically converted - no need to use <p> or <br> tags.
Talk Subject Comments
Comments here pertain to corrections to the text, not the subject itself
Article created on 12-April-2008. Views: 134733
This page was last modified on 21-April-2009.
All text is copyright and for personal use only but may be reproduced with the permission of the author.
Copyright Andrew Stuart @ Syndicated Puzzles Inc, 2012