GridWits
Extreme tier Technique 19 of 20 Used by Smart Hint

Jellyfish

A value's candidate cells across four rows (or columns) line up in the same four columns (or rows) — eliminate it everywhere else in those columns or rows.

How it works

  1. 1In rows 1, 3, 4 and 6, every candidate for digit 6 is confined to columns 1, 2, 4 and 6.
  2. 2Four rows need four 6s and have only those four columns available. This is a Jellyfish — the four-line version of X-Wing and Swordfish.
  3. 3Those cover columns must receive their 6s from the four pattern rows, so remove 6 from the same columns everywhere else, including all four candidates shown in row 2.
1 6 2 6 4 6 5 6 2 6 3 6 3 6 4 6 3 6 5 6 2 6 1 6
  • Candidates this technique rules out
  • Cells read together — The connecting line shows which cells combine to make the deduction.
  • Conclusion — The coloured candidate, or the final arrow when it lands outside the pattern, shows the result.
Next in the ladder Cross-Line Forcing →

Same as Cross-Line Consistency, but each ordering is also followed through: fill in every value it forces outright, and rule it out if that leaves some other row or column unfinishable.