scholarly journals Usage of Exact Algorithms to Enhance Stochastic Local Search Algorithms

2009 ◽  
pp. 103-134 ◽  
Author(s):  
Irina Dumitrescu ◽  
Thomas Stützle
Keyword(s):  
Local Search ◽  
Exact Algorithms ◽  
Search Algorithms ◽  
Stochastic Local Search ◽  
Local Search Algorithms

scholarly journals Circumspect descent prevails in solving random constraint satisfaction problems

2008 ◽  
Vol 105 (40) ◽  
pp. 15253-15257 ◽  
Author(s):  
Mikko Alava ◽  
John Ardelius ◽  
Erik Aurell ◽  
Petteri Kaski ◽  
Supriya Krishnamurthy ◽  
...  
Keyword(s):  
Local Search ◽  
Linear Time ◽  
Search Algorithm ◽  
Solution Space ◽  
Search Algorithms ◽  
Constraint Satisfaction Problems ◽  
Problem Instance ◽  
Stochastic Local Search ◽  
Local Search Algorithms ◽  
Local Energy Minimum

We study the performance of stochastic local search algorithms for random instances of the K-satisfiability (K-SAT) problem. We present a stochastic local search algorithm, ChainSAT, which moves in the energy landscape of a problem instance by never going upwards in energy. ChainSAT is a focused algorithm in the sense that it focuses on variables occurring in unsatisfied clauses. We show by extensive numerical investigations that ChainSAT and other focused algorithms solve large K-SAT instances almost surely in linear time, up to high clause-to-variable ratios α; for example, for K = 4 we observe linear-time performance well beyond the recently postulated clustering and condensation transitions in the solution space. The performance of ChainSAT is a surprise given that by design the algorithm gets trapped into the first local energy minimum it encounters, yet no such minima are encountered. We also study the geometry of the solution space as accessed by stochastic local search algorithms.

Path-relinking intensification methods for stochastic local search algorithms

2011 ◽  
Vol 18 (2) ◽  
pp. 193-214 ◽  
Author(s):  
Celso C. Ribeiro ◽  
Mauricio G. C. Resende
Keyword(s):  
Local Search ◽  
Search Algorithms ◽  
Path Relinking ◽  
Stochastic Local Search ◽  
Local Search Algorithms

An Enhanced Memetic Differential Evolution in Filter Design for Defect Detection in Paper Production

2008 ◽  
Vol 16 (4) ◽  
pp. 529-555 ◽  
Author(s):  
Ville Tirronen ◽  
Ferrante Neri ◽  
Tommi Kärkkäinen ◽  
Kirsi Majava ◽  
Tuomo Rossi
Keyword(s):  
Local Search ◽  
Differential Evolution ◽  
Defect Detection ◽  
High Performance ◽  
Filter Design ◽  
Industrial Process ◽  
Search Algorithms ◽  
Stochastic Local Search ◽  
Local Search Algorithms ◽  
Pivot Rules

This article proposes an Enhanced Memetic Differential Evolution (EMDE) for designing digital filters which aim at detecting defects of the paper produced during an industrial process. Defect detection is handled by means of two Gabor filters and their design is performed by the EMDE. The EMDE is a novel adaptive evolutionary algorithm which combines the powerful explorative features of Differential Evolution with the exploitative features of three local search algorithms employing different pivot rules and neighborhood generating functions. These local search algorithms are the Hooke Jeeves Algorithm, a Stochastic Local Search, and Simulated Annealing. The local search algorithms are adaptively coordinated by means of a control parameter that measures fitness distribution among individuals of the population and a novel probabilistic scheme. Numerical results confirm that Differential Evolution is an efficient evolutionary framework for the image processing problem under investigation and show that the EMDE performs well. As a matter of fact, the application of the EMDE leads to a design of an efficiently tailored filter. A comparison with various popular metaheuristics proves the effectiveness of the EMDE in terms of convergence speed, stagnation prevention, and capability in detecting solutions having high performance.

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