The XY-Chain technique is an advanced Sudoku solving strategy that helps you eliminate candidates in certain complex scenarios. It involves identifying a chain of cells, each with only two candidate numbers, that are linked together.
How to Identify an XY-Chain
An XY-Chain pattern consists of the following characteristics:
A chain of cells, where each cell contains only two candidate numbers (X and Y).
Each cell in the chain must see the next cell in the chain.
The chain must start and end with the same candidate number (X).
How the XY-Chain Technique Works
If the above conditions are met, you can eliminate the candidate number X from any cell that is seen by both the first and last cells in the chain.
Example of the XY-Chain Technique
Tips for Spotting XY-Chains
Look for cells with only two candidates.
Focus on cells that see each other.
Remember that the chain must start and end with the same candidate number.
