XY-Wing
When one pivot and two wings remove a shared candidate.
Explanation
An XY-Wing starts with a two-candidate pivot. Two peer cells each share one pivot candidate and both contain the same third candidate. Any cell that sees both wings cannot contain that shared third candidate.
Practice tip
Scan for two-candidate cells first. Then check whether two peers form matching wings around the pivot.
Example steps
- Find a pivot cell with candidates X/Y.
- Find one peer with X/Z and another peer with Y/Z.
- Remove Z from cells that see both wing cells.