X-Wing Sudoku: The Game-Changing 4-Cell Pattern That Masters Use - SudokuPuzzles.net

The X-Wing technique is one of the most powerful advanced Sudoku solving methods. It's a fish pattern that can eliminate candidates and unlock progress in difficult puzzles. Understanding this technique will significantly improve your ability to solve challenging Sudoku puzzles.

What Is the X-Wing Pattern?

An X-Wing occurs when a specific number appears as a candidate in exactly two cells in two different rows (or columns), and these cells are also in exactly two different columns (or rows). This creates a rectangular pattern that looks like an "X" when you connect the corners.

How to Identify an X-Wing

To find an X-Wing pattern:

1. Look for a specific number that appears as a candidate in exactly two cells in two different rows
2. Check if these cells are also in exactly two different columns
3. If they form a rectangle, you've found an X-Wing

How X-Wing Eliminates Candidates

When you find an X-Wing, you can eliminate the target number as a candidate from all other cells in the two columns (or rows) that contain the X-Wing. This is because the number must appear in one of the four corner cells of the X-Wing, making it impossible for it to appear elsewhere in those columns.

Example of X-Wing in Action

Imagine the number 7 appears as a candidate in cells (1,3), (1,7), (5,3), and (5,7). This forms an X-Wing pattern. You can then eliminate 7 as a candidate from all other cells in columns 3 and 7.

When to Look for X-Wing

X-Wing patterns typically appear in medium to difficult puzzles. Look for them when:

• You've exhausted basic techniques
• A number appears frequently as a candidate
• You're stuck and need a breakthrough

Practice Tips

To master the X-Wing technique:

• Practice on puzzles rated "Hard" or above
• Look for numbers that appear in exactly two cells per row/column
• Use pencil marks to track candidates
• Don't give up - X-Wing patterns can be subtle