XY-Wing
Level 6 · Orange Belt (Green Stripe)
Overview
XY-Wing uses three bi-value cells arranged so each pair shares a candidate. The pivot cell sees both wing cells, and the common candidate of the wings can be eliminated from cells that see both wings.
How It Works
- Find a pivot cell with candidates {X,Y} that sees two wing cells.
- One wing has candidates {X,Z}, the other has {Y,Z}.
- If pivot is X, one wing is Z. If pivot is Y, the other wing is Z.
- Eliminate Z from any cell that sees both wings.
Example
Find a two-candidate pivot cell r3c5 connected to two wing cells.
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Tips & Patterns
- All three cells must be bi-value (exactly 2 candidates).
- The pivot 'sees' both wings; wings may or may not see each other.
- Look for bi-value cells and check if they form the XY-YZ-XZ pattern.