Swordfish

Swordfish extends X-Wing to three rows and three columns. When a candidate appears 2-3 times in each of three rows, and all occurrences fall within the same three columns, eliminations can be made.

Technique

1. Find three rows where a candidate appears in at most 3 cells each, all within the same 3 columns.
2. The candidate must appear at least once in each row and column of the pattern.
3. Eliminate the candidate from other cells in those three columns.

Tips

• Swordfish requires careful tracking of candidate positions.
• Look for candidates that are restricted to few columns across multiple rows.
• Pencilmark highlighting greatly helps in spotting this pattern.