Sudoku techniques · Master
WXYZ-Wing in Sudoku
A WXYZ-Wing is a pivot and three wings holding only four candidates between them. Three of those numbers can occupy at most one cell each, so at least one cell must take the shared fourth, and any cell seeing every possible home for that number loses it.
Why it works
A pivot and its three wings hold only four candidates between them, and the first three fit at most one cell each, so at least one cell holds the shared fourth, and any cell that sees all its possible spots loses that candidate.
How to spot it
This is where wing patterns start to look like Almost Locked Sets, because that is what they are.
- Four cells, four distinct candidates total, one of which appears in cells that do not all share a unit.
- The shared candidate Z is the elimination target; everything else is structure.
- Look inside one box with two lines running through it; that geometry produces most of them.
Builds on
Worked example
These are the app's own lesson boards. Step through them the same way a hint does.
- 1
The pivot cell holds only candidates from 4, 7, 5 and 3, and it sees three bivalue wings: one with 4 and 3, one with 7 and 3, and one with 5 and 3. Together the four cells hold just those four candidates. This forms a WXYZ-Wing!
- 2
Each of 4, 7 and 5 fits at most one of the four cells, so at least one of the four cells must be 3. We can remove the candidate 3 from any other cell that sees every cell of the pattern holding the candidate 3.