Sudoku technique · First needed at: Expert
W-Wing
Two cells with the same two options are linked by a third line, so any cell seeing both loses the other option.
An example from a real puzzle
- Where the deduction happens
- The cells that make the pattern
- Candidates it removes
How to spot it
- Find two cells, not in the same group, with the same two candidates X and Y.
- Find a line where X has only two places, one seeing each of those cells.
- Any cell that sees both of the two-candidate cells cannot be Y.
Why it works
One of the two places on the line holds X, which forces the cell it sees to be Y. So one of the pair is always Y, and a cell seeing both loses it.
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