Notice of Retraction Rating and Generating Sudoku Puzzles

The Sudoku puzzle has achieved worldwide popularity recently, and attracted great attention of the computational intelligence community. How to evaluate the difficulty of the puzzle is a difficult thing. In this paper, the nondeterministic degree is regarded as the main factor that affects Sudoku puzzle and we get the difficulty through summing the entropy of each step. We give the difficulty level model by mapping the difficulty to integers. An algorithm is developed to generate Sudoku puzzles when given a difficulty level.