Pattern

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

• Locked Candidates
• Subsets
• Fish
• Skyscraper
• 2-String Kite
• Empty Rectangle
• XY-Wing
• Uniqueness Test
• BUG

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.

See Also

• Pattern Overlay Method