X-Wing

X-Wing is a fish pattern using two rows and two columns. When a candidate appears in exactly two cells in two different rows, and these four cells share the same two columns, the candidate can be eliminated from other cells in those columns.

Technique

1. Find a candidate that appears in exactly two cells in a row.
2. Find another row where the same candidate appears in exactly two cells in the same columns.
3. These four cells form a rectangle.
4. The candidate must be in two diagonal corners.
5. Eliminate the candidate from other cells in those two columns.

Tips

• X-Wings work on rows (eliminating from columns) or columns (eliminating from rows).
• Look for candidates with exactly 2 occurrences per row/column.
• The pattern forms a rectangle - visualize the 'X' shape.