Practise: XY-Wing
Start with three marked two-candidate cells: which cell is the hinge, and which digit do the two wings share?
The prepared notes show one hinge and two wings. Find their shared digit, then look only at notes that see both wings; do not place a digit yet.
Example 1 of 4
Your turn first
Your turn first
Find the two-candidate hinge. Its two neighbours each share one hinge digit and share 9 with each other. Which prepared 9-notes see both wings?
Remember
An XY-Wing has a two-candidate hinge and two two-candidate wings. Each wing shares one hinge digit, and both share a third digit. One wing must contain that third digit, so it can be removed from any cell seeing both wings.
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