Within the context of Sudoku, a pattern can be:
- A recognizable structure in the remaining candidates for a single digit.
- A template that represents one possible configuration for all instances of a single digit.
- A set of cells that can be recognized by predefined characteristics. (subset, ALS)
Players often make a distinction between pattern-based solving techniques and chains or loops. However, recent developments in solving techniques have resulted in several advanced solving techniques where patterns are embedded as nodes in chains.
Pattern-based Solving techniques
Note that a single ALS is a pattern, but not a solving technique. The techniques that use ALS either require more than one or use them in chains.