title: A Hybrid alldifferent-Tabu Search Algorithm for Solving Sudoku Puzzles.
abstract: The Sudoku problem is a well-known logic-based puzzle of combinatorial number-placement. It consists in filling a n(2) × n(2) grid, composed of n columns, n rows, and n subgrids, each one containing distinct integers from 1 to n(2). Such a puzzle belongs to the NP-complete collection of problems, to which there exist diverse exact and approximate methods able to solve it. In this paper, we propose a new hybrid algorithm that smartly combines a classic tabu search procedure with the alldifferent global constraint from the constraint programming world. The alldifferent constraint is known to be efficient for domain filtering in the presence of constraints that must be pairwise different, which are exactly the kind of constraints that Sudokus own. This ability clearly alleviates the work of the tabu search, resulting in a faster and more robust approach for solving Sudokus. We illustrate interesting experimental results where our proposed algorithm outperforms the best results previously reported by hybrids and approximate methods.
authors.affiliation: Pontificia Universidad Católica de Valparaíso, 2362807 Valparaíso, Chile ; Universidad Autónoma de Chile, 7500138 Santiago, Chile ; Universidad Cientifica del Sur, Lima 18 Lima, Peru.
authors.forename: Ricardo
authors.identifier: 0000-0002-5755-6929
authors.initials: R
authors.lastname: Soto
authors.affiliation: Pontificia Universidad Católica de Valparaíso, 2362807 Valparaíso, Chile ; Universidad Central de Chile, 8370178 Santiago, Chile ; Universidad San Sebastián, 8420524 Santiago, Chile.
authors.forename: Broderick
authors.initials: B
authors.lastname: Crawford
authors.affiliation: Pontificia Universidad Católica de Valparaíso, 2362807 Valparaíso, Chile.
authors.forename: Cristian
authors.identifier: 0000-0001-9460-8719
authors.initials: C
authors.lastname: Galleguillos
authors.affiliation: Escuela de Ingeniería Industrial, Universidad Diego Portales, 8370109 Santiago, Chile.
authors.forename: Fernando
authors.initials: F
authors.lastname: Paredes
authors.affiliation: Facultad de Ingeniería, Universidad Santo Tomás, 2561694 Viña del Mar, Chile.
authors.forename: Enrique
authors.initials: E
authors.lastname: Norero
mesh_terms: D000465:Algorithms; D001185:Artificial Intelligence; D005716:Game Theory; D006801:Humans; D011340:Problem Solving; D012984:Software