Key Points
  • Y-Wing (also called XY-Wing) uses 3 bi-value cells to eliminate a candidate from cells that see both pincers
  • W-Wing uses 2 cells with the same two candidates linked by a strong link on one of those candidates
  • Both patterns work even when the cells involved are not in the same unit
  • The key to spotting them: look for cells with exactly two candidates first
  • These are standard Expert-level techniques — expect to need them on every Expert puzzle

Y-Wing (XY-Wing) Explained

An XY-Wing has three cells:

  • Pivot: Has candidates XY (exactly two)
  • Pincer 1: Shares a unit with the pivot; has candidates XZ
  • Pincer 2: Shares a unit with the pivot (different unit); has candidates YZ

The logic: if pivot = X, then Pincer 1 must be Z. If pivot = Y, then Pincer 2 must be Z. Either way, Z must be in one of the pincers. Any cell that can "see" both pincers (shares a unit with each) cannot be Z — eliminate Z from it.

How to Spot XY-Wing

  1. Find all cells with exactly two candidates (bi-value cells)
  2. For each bi-value cell, look for two other bi-value cells in its rows, columns, or boxes
  3. Check if the three cells form an XY, XZ, YZ pattern (one candidate shared between each pair)
  4. Find cells that see both pincers — eliminate the shared Z candidate from them

W-Wing Explained

A W-Wing uses two cells that have the same two candidates XY, connected by a strong link on one of those candidates (say X). A strong link means X can only be in those two specific cells within some unit.

Because the two XY cells are linked by X, the other candidate Y cannot be in both cells simultaneously — exactly one of the two cells must be Y. Any cell that sees both XY cells can have Y eliminated.

Practical Tips

Build a habit of marking bi-value cells when you fill in pencil marks — some players circle them or highlight them. Bi-value cells are the building blocks of virtually all chain-based techniques at Expert level and above. If you can identify all bi-value cells quickly, XY-Wing and W-Wing become much easier to spot. Check the full techniques library for worked visual examples.