Hard technique · Technique Academy

X-Wing

An X-Wing is a digit that appears in exactly two cells in each of two rows, with those cells sharing the same two columns. The four cells are the corners of a rectangle.

Professor Cryptic, the owl who teaches in the app
Professor Cryptic is thinking

The reasoning

Why does the X-Wing work?

Either diagonal of the rectangle holds the digit, and either way both columns get theirs from these two rows. So no other cell in those columns can hold it. Swap rows and columns and the same logic runs sideways.

A worked example

What does the X-Wing look like on a real board?

X-Wing worked exampleA sudoku board with pencil marks. The X-Wing uses R2C2, R2C4, R8C2, R8C4 and digit 2 (columns 2 and 4, rows 2 and 8). The move strikes candidates 2 in R2C5, 2 in R2C6, 2 in R8C6.1287912643551292312342487634687519212612378937549546232737817384516298951632474612327924751684671252489163
The move strikes candidates 2 in R2C5, 2 in R2C6, 2 in R8C6. Digit 2, columns 2 and 4, rows 2 and 8.
  • Cells that form the pattern
  • Cells that lose a candidate
  • Struck digit: ruled out

Make it stick

How can you practise the X-Wing?

The Technique Academy in Cryptic gives every technique its own lesson and 5 practice boards that need exactly this move.

Get it onGoogle PlayPlay Cryptic on the web

Further reading: HoDoKu's page on this family of techniques.

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