Solving Single-digit Sudoku Subproblems
arXiv:1202.5074
Abstract
We show that single-digit "Nishio" subproblems in nxn Sudoku puzzles may be solved in time o(2^n), faster than previous solutions such as the pattern overlay method. We also show that single-digit deduction in Sudoku is NP-hard.
12 pages, 5 figures. To appear at the 6th International Conference on Fun with Algorithms (FUN 2012). This revision simplifies the algorithm description and adds more references to related prior work