scholarly journals The 2008 Classic Paper Award: Summary and Significance

AI Magazine ◽  
2010 ◽  
Vol 31 (4) ◽  
pp. 109
Author(s):  
Peter Friedland
Keyword(s):  
Local Search ◽  
Constraint Satisfaction ◽  
Wide Class ◽  
Large Scale ◽  
Constraint Satisfaction Problems ◽  
Paper Award ◽  
Scheduling Problems ◽  
Repair Method ◽  
Mark Johnston ◽  
Classic Paper

We at the NASA laboratory believed that our best work came when we simultaneously advanced AI theory and provided immediately usable solutions for current NASA problems. “Solving Large-Scale Constraint Satisfaction and Scheduling Problems Using a Heuristic Repair Method,” by Steve Minton, Mark Johnston, Andy Phillips, and Phil Laird clearly achieved both. It proved that local search and repair was applicable to a wide class of constraint satisfaction problems and clearly explicated the theory behind that proof.

IMPROVING EVOLUTIONARY ALGORITHMS FOR EFFICIENT CONSTRAINT SATISFACTION

1999 ◽  
Vol 08 (04) ◽  
pp. 363-383 ◽  
Author(s):  
PETER STUCKEY ◽  
VINCENT TAM
Keyword(s):  
Evolutionary Algorithms ◽  
Local Search ◽  
Constraint Satisfaction ◽  
Operations Research ◽  
Large Scale ◽  
Optimization Problems ◽  
Constraint Satisfaction Problems ◽  
Search Methods ◽  
Local Search Methods ◽  
Considerable Success

Hard or large-scale constraint satisfaction and optimization problems, occur widely in artificial intelligence and operations research. These problems are often difficult to solve with global search methods, but many of them can be efficiently solved by local search methods. Evolutionary algorithms are local search methods which have considerable success in tackling difficult, or ill-defined optimization problems. In contrast they have not been so successful in tackling constraint satisfaction problems. Other local search methods, in particular GENET and EGENET are designed specifically for constraint satisfaction problems, and have demonstrated remarkable success in solving hard examples of these problems. In this paper we examine how we can transfer the mechanisms that were so successful in (E)GENET to evolutionary algorithms, in order to tackle constraint satisfaction algorithms efficiently. An empirical comparison of our evolutionary algorithm improved by mechanisms from EGENET and shows how it can markedly improve on the efficiency of EGENET in solving certain hard instances of constraint satisfaction problems.

scholarly journals Semantic Width and the Fixed-Parameter Tractability of Constraint Satisfaction Problems

2020 ◽  
Author(s):  
Hubie Chen ◽  
Georg Gottlob ◽  
Matthias Lanzinger ◽  
Reinhard Pichler
Keyword(s):  
Constraint Satisfaction ◽  
Fundamental Problem ◽  
Constraint Satisfaction Problems ◽  
Fixed Parameter Tractability ◽  
Scheduling Problems ◽  
Fixed Parameter Tractable ◽  
Database Theory ◽  
Formal Framework ◽  
Fixed Parameter

Constraint satisfaction problems (CSPs) are an important formal framework for the uniform treatment of various prominent AI tasks, e.g., coloring or scheduling problems. Solving CSPs is, in general, known to be NP-complete and fixed-parameter intractable when parameterized by their constraint scopes. We give a characterization of those classes of CSPs for which the problem becomes fixed-parameter tractable. Our characterization significantly increases the utility of the CSP framework by making it possible to decide the fixed-parameter tractability of problems via their CSP formulations. We further extend our characterization to the evaluation of unions of conjunctive queries, a fundamental problem in databases. Furthermore, we provide some new insight on the frontier of PTIME solvability of CSPs. In particular, we observe that bounded fractional hypertree width is more general than bounded hypertree width only for classes that exhibit a certain type of exponential growth. The presented work resolves a long-standing open problem and yields powerful new tools for complexity research in AI and database theory.

scholarly journals Minimizing conflicts: a heuristic repair method for constraint satisfaction and scheduling problems

1992 ◽  
Vol 58 (1-3) ◽  
pp. 161-205 ◽  
Author(s):  
Steven Minton ◽  
Mark D. Johnston ◽  
Andrew B. Philips ◽  
Philip Laird
Keyword(s):  
Constraint Satisfaction ◽  
Scheduling Problems ◽  
Repair Method

scholarly journals An Ant Colony Optimization Based on Information Entropy for Constraint Satisfaction Problems

Entropy ◽  
2019 ◽  
Vol 21 (8) ◽  
pp. 766 ◽  
Author(s):  
Boxin Guan ◽  
Yuhai Zhao ◽  
Yuan Li
Keyword(s):  
Local Search ◽  
Ant Colony Optimization ◽  
Constraint Satisfaction ◽  
Information Entropy ◽  
Hypothesis Test ◽  
Constraint Satisfaction Problem ◽  
Constraint Satisfaction Problems ◽  
Ant Colony ◽  
Cost Comparison ◽  
Solution Quality

Solving the constraint satisfaction problem (CSP) is to find an assignment of values to variables that satisfies a set of constraints. Ant colony optimization (ACO) is an efficient algorithm for solving CSPs. However, the existing ACO-based algorithms suffer from the constructed assignment with high cost. To improve the solution quality of ACO for solving CSPs, an ant colony optimization based on information entropy (ACOE) is proposed in this paper. The proposed algorithm can automatically call a crossover-based local search according to real-time information entropy. We first describe ACOE for solving CSPs and show how it constructs assignments. Then, we use a ranking-based strategy to update the pheromone, which weights the pheromone according to the rank of these ants. Furthermore, we introduce the crossover-based local search that uses a crossover operation to optimize the current best assignment. Finally, we compare ACOE with seven algorithms on binary CSPs. The experimental results revealed that our method outperformed the other compared algorithms in terms of the cost comparison, data distribution, convergence performance, and hypothesis test.

scholarly journals Solving Weighted Constraint Satisfaction Problems with Memetic/Exact Hybrid Algorithms

2009 ◽  
Vol 35 ◽  
pp. 533-555 ◽  
Author(s):  
J. E. Gallardo ◽  
C. Cotta ◽  
A. J. Fernández
Keyword(s):  
Constraint Satisfaction ◽  
Large Scale ◽  
Constraint Satisfaction Problem ◽  
Heuristic Method ◽  
Optimal Solution ◽  
Constraint Satisfaction Problems ◽  
Still Life ◽  
Level Model ◽  
Weighted Constraint

A weighted constraint satisfaction problem (WCSP) is a constraint satisfaction problem in which preferences among solutions can be expressed. Bucket elimination is a complete technique commonly used to solve this kind of constraint satisfaction problem. When the memory required to apply bucket elimination is too high, a heuristic method based on it (denominated mini-buckets) can be used to calculate bounds for the optimal solution. Nevertheless, the curse of dimensionality makes these techniques impractical on large scale problems. In response to this situation, we present a memetic algorithm for WCSPs in which bucket elimination is used as a mechanism for recombining solutions, providing the best possible child from the parental set. Subsequently, a multi-level model in which this exact/metaheuristic hybrid is further hybridized with branch-and-bound techniques and mini-buckets is studied. As a case study, we have applied these algorithms to the resolution of the maximum density still life problem, a hard constraint optimization problem based on Conway's game of life. The resulting algorithm consistently finds optimal patterns for up to date solved instances in less time than current approaches. Moreover, it is shown that this proposal provides new best known solutions for very large instances.

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