The Shameless Sashimi

Sashimi 5-wing and 5-chainWhich Sashimi did you find in the LA Times 5/14/09 5-panel?  Was this one of them?  We could describe it as a Sashimi 5-wing in r13 with fin r3c1.  Note the new 5-chain added to the panel.  It also removes the victim, and the toxic ends are the fin and the candidate X-wing candidate whose position is taken by the victim.  The fin is seen by ER wink in this case.

In a Sashimi X-wing, the line missing one of the “corner” candidates must have a fin.  Otherwise the remaining candidate would be a clue.

Thinking about these associations, we can conclude that  every Sashimi X-wing is not only a 3 link chain, it is a skyscraper!  And in every skyscraper, there lurks a Sashimi  X-wing.  Add yours to the skyscraper panel.

But wait, there could be another victim of the 5-chain 1 skyscraper  above.  If r8c1 sees the other end r1c5, . . .  And it does, again by ER wink.

This shows that not every 3 link chain is a Sashimi X-wing, because not every one is a skyscraper . You could construct a counter example any of these panels by moving one 5-candidate.

These facts suggest a politician’s strategy for Sashimi X-wings.  In line marking, look for skyscrapers, then brag to your friends about finding a Sashimi X-wing.  If you don’t  care for politics, forget about Sashimi X-wings and just look for live three-link X-chains.

almost nice slink loopDo you get your sysudokie gold star for a slinky loop?   You get it if you found this nearly winkless loop or one of its equivalent variations.

Although it generates  four clues at once,  it is no more decisive than any of the Sashimi X-wing/skyscrapers on the panel, because the slinks just spread the joy around.  It’s a preview of the coming attraction of coloring.


For n-fish of n more than 2, fish lines of less than n X-candidates commonplace.  Only those with a single X-candidate line deserve the “Sashimi” label.  This line also has the fin.   Just like the Sashimi X-wing and for the same reason, victims of the “single X + fin” n > 2 fish are those victims of the definned fish that see the fin.  Once Sashimi are recognized and the fin is identified. They are analyzed for fin box and kraken victims no differently.

Andrew Stuart Sashimi swordfishAndrew Stuart presents this “famed” Sashimi Swordfish” in The Logic of Sudoku.  It is remarkable how only one of the r2 candidates matches the three fish positions defined  by r4 and r6. How many of these have I passed up?

The o’s in the diagram are potential victims of the sashimi.  Virginia found that none are kraken victims.  Maybe you should check these out, as well.


The next post is about Mutant and Franken Fish, made of boxes as well as lines. A Maestro Megastar puzzle formerly appearing here as a “homework assignment”, was removed when it was found to collapse before reaching the mutant fish that it was meant to illustrate.


About Sudent

My real name is John Welch. I'm a happily married, retired professor (computer engineering), timeshare traveling, marathon running father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. The blog is about Sudoku solving. It covers how to start, basic solving to find candidates efficiently, and advanced solving methods in an efficient order of battle. It is about human solving methods, not computer solving.
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2 Responses to The Shameless Sashimi

  1. Ruan says:

    I think it was the Skyscraper logic on this one that caught pelope out, because the actual Sudoku logic didn’t require any sort of particularly advanced logic (not even naked pairs or anything higher).So far as I’m concerned, in terms of complex logic I don’t intend to ever require any strategy which isn’t intuitively obvious to anyone who has solved a reasonable number of Sudoku. In other words, if you’re not likely to work it out on your own eventually then I think the strategy is too hard (at least for a general audience).For definitions of strategies, take a look at . (NB I only use the ones near the top, and the solving technique called ‘skyscraper’ has nothing to do with skyscraper sudoku/skyscraper puzzles!)

    • Sudent says:

      To each is own, Ruan. I’m not writing for a general audience, and I’m a devotee of self discovery. Techniques of efficient human solving are far from obvious, however. Developing and explaining them requires careful writing and a diligent search for good examples. I have to believe that other readers appreciate this. The logic getting you to the skyscraper examples was spelled out completely in the blog. Why don’t you point out how you can get there more efficiently, without guessing?

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