Jellyfish Technique
advancedThe ultimate fish pattern with four rows and columns
Jellyfish is the 4x4 extension of the fish family, involving four rows and four columns.
Understanding the Concept
A candidate appears in four rows, confined to the same four columns.
Follows the same logic as X-Wing and Swordfish, extended to 4x4.
Extremely rare in practice - most puzzles never require Jellyfish.
The candidate can be eliminated from all other cells in the four columns.
Named to continue the fish theme (though jellyfish aren't fish!).
Mainly of theoretical interest; if you need Jellyfish, consider if you missed something easier.
Examples
Theoretical Jellyfish
If a digit appears in 4 rows confined to the same 4 columns, eliminations can be made in those columns.
Pro Tips
- •Jellyfish are extraordinarily rare
- •Almost never required in published puzzles
- •If you think you need one, double-check for easier patterns
- •More important to master X-Wing and Swordfish
