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Sudoku technique · Specialty reference · reference
Backtracking and exact search
Systematic search enumerates solutions or disproves a candidate by contradiction. This app uses it behind the scenes for validation.
How to spot it
Separate the job of finding an answer from the job of explaining a human deduction.
The common mistake
The safety checker is not the reasoning used to discover the named pattern. It does not make a guess into a named technique.
Learn this first
Sudoku rules.
Further reading: hodoku.sourceforge.net