The New Sudoku Players' Forum

[Hambone]

https://imgur.com/a/aAZsTf9

Grateful your advice as to why this fails.
Tks

[eleven]

Hm, this is so far from being a swordfish, that i guess, that you don't know it's definition:
If a digit in 3 rows (or columns resp.) is restricted to (only appears in) 3 columns (rows), you can eliminate it from the other cells of that columns (rows).
(wherever you place it in the 3 rows, you also already occupy the 3 columns)

Here the 7 is neither restricted to 3 columns in rows 348 nor to 3 rows in columns 178.

btw there are 2 skyscrapers for digit 9 (in r28 or c28), which solve the puzzle.

[Hambone]

Hi eleven,
Your reply much appreciated.
You are correct in that my interpretation of the necessary conditions was incorrect.
Now its onto skyscrapers....

[Hambone]

duplicate deleted

[eleven]

Here are some links for skyscrapers:
hodoku solving techniques
sudopedia
or look at
Strong Links for Beginners
For many solvers skyscrapers are a special case of finned x-wings, which in turn are grouped skyscrapers.