43,737 research outputs found
A dynamic neighborhood learning-based gravitational search algorithm
Balancing exploration and exploitation according to evolutionary states is crucial to meta-heuristic search (M-HS) algorithms. Owing to its simplicity in theory and effectiveness in global optimization, gravitational search algorithm (GSA) has attracted increasing attention in recent years. However, the tradeoff between exploration and exploitation in GSA is achieved mainly by adjusting the size of an archive, named Kbest, which stores those superior agents after fitness sorting in each iteration. Since the global property of Kbest remains unchanged in the whole evolutionary process, GSA emphasizes exploitation over exploration and suffers from rapid loss of diversity and premature convergence. To address these problems, in this paper, we propose a dynamic neighborhood learning (DNL) strategy to replace the Kbest model and thereby present a DNL-based GSA (DNLGSA). The method incorporates the local and global neighborhood topologies for enhancing the exploration and obtaining adaptive balance between exploration and exploitation. The local neighborhoods are dynamically formed based on evolutionary states. To delineate the evolutionary states, two convergence criteria named limit value and population diversity, are introduced. Moreover, a mutation operator is designed for escaping from the local optima on the basis of evolutionary states. The proposed algorithm was evaluated on 27 benchmark problems with different characteristic and various difficulties. The results reveal that DNLGSA exhibits competitive performances when compared with a variety of state-of-the-art M-HS algorithms. Moreover, the incorporation of local neighborhood topology reduces the numbers of calculations of gravitational force and thus alleviates the high computational cost of GSA
Superior Exploration-Exploitation Balance with Quantum-Inspired Hadamard Walks
This paper extends the analogies employed in the development of
quantum-inspired evolutionary algorithms by proposing quantum-inspired Hadamard
walks, called QHW. A novel quantum-inspired evolutionary algorithm, called
HQEA, for solving combinatorial optimization problems, is also proposed. The
novelty of HQEA lies in it's incorporation of QHW Remote Search and QHW Local
Search - the quantum equivalents of classical mutation and local search, that
this paper defines. The intuitive reasoning behind this approach, and the
exploration-exploitation balance thus occurring is explained. From the results
of the experiments carried out on the 0,1-knapsack problem, HQEA performs
significantly better than a conventional genetic algorithm, CGA, and two
quantum-inspired evolutionary algorithms - QEA and NQEA, in terms of
convergence speed and accuracy.Comment: 2 pages, 2 figures, 1 table, late-breakin
A model for characterising the collective dynamic behaviour of evolutionary algorithms
Exploration and exploitation are considered essential notions in evolutionary algorithms. However, a precise interpretation of what constitutes exploration or exploitation is clearly lacking and so are specific measures for characterising such notions. In this paper, we start addressing this issue by presenting new measures that can be used as indicators of the exploitation behaviour of an algorithm. These work by characterising the extent to which available information guides the search. More precisely, they quantify the dependency of a population's activity on the observed fitness values and genetic material, utilising an empirical model that uses a coarse-grained representation of population dynamics and records information about it. The model uses the k-means clustering algorithm to identify the population's "basins of activity". The exploitation behaviour is then captured by an entropy-based measure based on the model that quantifies the strength of the association between a population's activity distribution and the observed fitness landscape information. In experiments, we analysed the effects of the search operators and their parameter settings on the collective dynamic behaviour of populations. We also analysed the effect of using different problems on algorithm behaviours.We define a behavioural landscape for each problem to identify the appropriate behaviour to achieve good results and point out possible applications for the proposed model
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