sudokUI › Sudoku techniques › Leviathan
Leviathan in sudoku
7-fish · flip side of a smaller fish · how it fits
Digit X has two to seven candidates in each of seven rows, all lying in the same seven columns, or likewise with rows and columns swapped.
Why it works
Each of the seven rows places X in a different one of the seven columns, so all seven 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 two still need X, and they form an X-Wing 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 Leviathan, the puzzle's difficulty rating grows by 470. Its class is Unfair. How the rating works.
More basic fish
X-Wing · Swordfish · Jellyfish · Squirmbag · Whale
← WhaleRemote Pair →