W-Wing

The W-Wing is a clean, powerful pattern built from two identical bi-value cells and a single strong link between them. Once you have full pencil marks it's surprisingly easy to spot, and it makes eliminations the simple wings can't reach.

What is a W-Wing?

Find two cells, not seeing each other, that hold the same two candidates — say {3, 7}. Now look for a strong link on one of those digits (say 7) connecting the two cells: a unit where 7 has only two homes, one seeing the first cell and one seeing the second. The logic: if either {3,7} cell were 7, the strong link forces the other to be 3 — so one of the two cells is a 3. Any cell seeing both can't be 3.

Step by step

1. Find two matching bi-value cells with the same two candidates, not seeing each other.
2. Look for a strong link on one of the digits connecting them.
3. Eliminate the other digit from any cell that sees both bi-value cells.

Where it fits among the wings

The W-Wing sits alongside the XY-Wing and XYZ-Wing, but its shape is different: instead of a pivot and pincers, it's a matched pair of bi-value cells bridged by a conjugate link. Many solvers find it the easiest of the three to spot once they're used to scanning for repeated candidate pairs, because the two {3, 7} cells jump out and you only then need to check for a link between them.

Common mistakes

• Cells with different candidates. The two cells must share exactly the same pair — {3, 7} and {3, 8} won't do.
• No genuine strong link. The connecting digit must have only two homes in the linking unit, one seeing each bi-value cell.
• Eliminating the wrong digit. You remove the digit that isn't the one carrying the strong link — here the 3, not the 7.

Once the W-Wing feels natural, you're well placed to move on to remote pairs and full chains, which extend the same alternating logic over longer runs of cells.

Which Sudoku types is this best for?

The same logic applies across variants, but it pays off more in some than others.