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📋 Y-Wing (XY-Wing) – Advanced Technique

A two-candidate pivot links two wings that each share one candidate with it. The shared candidate is eliminated from any cell that sees both wings. Illustrated with 2 images.

What Is Y-Wing (XY-Wing)?

Y-Wing is a three-cell pattern: a two-candidate pivot (A/B) plus two wings that see the pivot — one {A,C} and the other {B,C}. Because both wings contain C, any cell that sees both wings cannot be C.

Step-by-Step Example

Step 1: Identify pivot and two wings for the Y-Wing
1) Pivot has {1,2}; wings are {1,3} and {2,3}. The shared candidate is 3.
Step 2: Eliminate the shared candidate from cells that see both wings
2) Remove 3 from any cell that can see both wings (red circle). This often forces placements.

How to Use It

  • Find a pivot with exactly two candidates.
  • Locate two wings: {A,C} and {B,C}, both seeing the pivot.
  • Eliminate C from cells that see both wings.

Common Pitfalls

  • Wings with more than two candidates are invalid.
  • Wings do not have to see each other; they must see the pivot.
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