Sudoku Techniques: Y-Wing
Learning to become a more proficient Sudoku player is highly rewarding, especially when you make use of well-known techniques that make solving the puzzle easier. Once you have a good grasp of the basic terms and mechanics of Sudoku, you can then try out these techniques and incorporate them into your solving style to solve medium Sudoku puzzles and higher difficulties.
There are many known tricks and tactics for Sudoku players that can help work through the logic problems of the game, and one of the most useful ones is the Y-Wing. Playing with this technique can significantly increase your Sudoku puzzle-solving skill, and is known to have created other offshoot tricks.
What is the Y-Wing, why is it called that and how does it work? Continue reading down below to learn more Sudoku tips and info!
What Is the Y-Wing?
The Y-Wing is a very useful technique in eliminating numbers in three different cells containing two candidates, regardless if it's an easy Sudoku puzzle or a hard one. However, it’s important to remember that it only works on Sudoku puzzles that have been sufficiently pencil marked with candidates, must have cells that have two-digit candidates and have to meet certain conditions to work.
The first condition is that the three cells to be used in the Y-Wing must share a specific number with one cell. The technique doesn’t have a set distance, and you can use it to press on and finish harder puzzles. Let’s use this example:
Here, we can see that cells r2c5 (3,8), r2c6 (3,6) and r9c6 (6,8) all have candidates in common with one of the cells. Cells r2c5 and r2c6 share the candidate digit 3, r2c6 and r9c6 share the candidate 6, and r2c5 and r9c6 have no similarities.
Now that we’ve got them identified in the Sudoku grid, it’s time to determine the parts of the Y-Wing. This Sudoku technique works off a “pivot cell”, which shares similar candidates with both of the other cells. In this case, our pivot cell is r2c6, and it’s connected to the other two cells, which are called the “wings” of the technique. If you connect them with a line, then it ends up looking like a Y, hence the name.
So to summarize, our pivot cell is r2c6, and the wings are r2c5 and r9c6.
How Does It Work in Free Sudoku Puzzles?
Now to discuss how the technique works in the game!
The Y-Wing works by eliminating candidate numbers using logic around the pivot cell. Our pivot cell has candidates (3,6), while the two wings have candidates (3,8) and (6,8). If the pivot cell is assumed to have a value of 3, then we’ll eliminate candidate 3 in cell r2c5. If the pivot cell is a 6, then candidate 6 is removed in cell r9c6.
Again, to summarize, if r2c6 is (3), then r2c5 (3,8). If r2c6 is (6), then r9c8 (6,8). Regardless of whether one of the wings loses a 3 or a 6 in their candidate notations, one of them is a guaranteed 8.
This results in the elimination of two candidates and arriving at two guaranteed answers at the same time, helping you reach the final answer for your Sudoku game.
The Y-Wing and Further Elimination
Another great aspect of this technique is that it eliminates other candidates in the same row, column and box/subgrid where the two wings are located. In our example, since the guaranteed number is 8, we can then further eliminate the candidates around them.
If cells containing the candidate number 8 are within the same row, column or box/subgrid of the wings, we can then safely remove them from the notes, which further decreases the number of candidate digits that need to be eliminated in the grid and helps fill out other sections of the puzzle.
Adding the Y-Wing to Your Skillset
Like any other great tool in a game, there is no set way to use the Y-Wing in your bag of Sudoku tricks. It’s important to remember that all these techniques are situational and rely heavily on the skill of the player to make the game’s logic work.
Even if you know how the Sudoku Y-Wing works, it can’t be properly used if there are no cells that meet its conditions or if you haven’t sufficiently learned how to fill in candidates. If you're still on the fence about your understanding of the technique, try it out and play easy Sudoku puzzles first on our site, sudokuconquest.com.
As for serious players looking to make use of it, learning other techniques, such as the X-Wing and Swordfish, and using them together with the Y-Wing can make even hard Sudoku puzzles easier with the right application and practice!