sudokUI › Sudoku techniques › Squirmbag
Squirmbag in sudoku
5-fish · flip side of a smaller fish · how it fits
Digit X has two to five candidates in each of five rows, all lying in the same five columns, or likewise with rows and columns swapped.
Why it works
Each of the five rows places X in a different one of the five columns, so all five columns get their X from these rows. Remove X from all other cells in those columns, or in those rows for the swapped form.
How to spot it
Look at the columns outside the pattern: at most four still need X, and they form smaller fish or singles giving the same eliminations.
Implemented, but never needed: an easier technique always reaches the same result first.
In a puzzle's rating
Each time the solver needs Squirmbag, the puzzle's difficulty rating grows by 470. Its class is Unfair. How the rating works.