Swordfish identities

[zoltag]

There is confusion between sashimi and finned swordfish. (Not just in my mind. LOL)

The analyzer reports sashimi and the hints take you to finned.
The hint has been correct in all that I remember.

Here is one such, I have UR all off, else the swords won't come up.

Code: Select all

. . 6|. . 8|. 1 3
. 8 .|9 . .|. . .
9 . .|3 4 .|. 7 .
-----+-----+-----
. 7 3|8 . .|4 . 9
. . 1|. . .|3 2 .
2 . .|. . .|. . .
-----+-----+-----
. . .|4 8 .|. . .
1 . 9|. 3 .|. 4 .
7 . .|1 . .|. . 6

[MorganNY]

I noted a similar discrepancy. This will also pertain to the solving guide but a single post make more sense.
I was doing today's nightmare in SudoCue. I got to a point the [vague] hint indicated a Sashimi X-wing. when I used the hint[F8] to show it to me, it identified the step as a Finned X-wing. I'm not sure what nuance, if any, separates these patterns. My confusion stems primarily from differences in what the program describes, and how it is covered in the Solving guide. The program often [vaguely] hints at a 'Skyscraper' (which I'm finally sort of getting), and recently, color traps and wraps (which I am enjoying). It's at this point that parity starts making sense. Skyscrapers, Sashimis etc all fall under what the solving guide calls "Color Wings", a term sudocue has never used. What separates these patterns?
Since this is my first post, I'd like to thank you for the great strides my education in sudoku solving has taken since finding your page, your guide and your program. The learning curve set has also been a big help.
Warmest regards,
Morgan

[Ruud]

Thanks for reporting this issue.

There has been some confusion about the difference between finned fish and sashimi fish, but the latest consensus is that when you disregard the fin(s), if the remaining candidates form a complete fish pattern, it is a finned fish, but if it degenerates to a smaller fish or singles, it is a sashimi fish.

SudoCue still uses the earlier (incorrect) definition, which only checks whether the box containing the fin also has candidates that belong to the underlying fish pattern. I will change this in the coming release, along with some performance improvements in the finned fish function.

About Color Wings

Before I implemented 2-string kite, skyscraper, finned fish and Empty Rectangles, SudoCue often used Color Wing, but these patterns are so powerful, that a real Color Wing has become extremely rare. Keep an eye on the Monday and Tuesday Nightmares. Color Wing is one of the techniques that will be selected for these Nightmares.

cheers,
Ruud