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W-Wing

When two matching pairs are connected by a strong link.

Explanation

A W-Wing uses two cells with the same two candidates and a strong link on one of those candidates. The link proves one wing must hold the other candidate, so that candidate can be removed from cells seeing both wings.

W-Wing example Sudoku board 4 6 7 2 5 8 1 5 7 3 8 6 8 9 1 4 7 2 8 3 2 5 1 3 5 4 6 1 8 1 2 4 8 7 6 3 9 6 4 9 9 3 8 4 2 5 4 1 6 2 9 3 8
An example board where W-Wing applies

Practice tip

Find matching two-note cells first. Then check whether one candidate has a conjugate pair that touches both wings.

Example steps

  1. Find two non-seeing cells with the same two candidates.
  2. Find a strong link on one candidate that sees both wing cells.
  3. Remove the other candidate from cells that see both wings.

Try this technique on a real puzzle.

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