A New Memory Based Variable-Length Encoding Genetic Algorithm for Multiobjective Optimization
This paper presents a new memory-based variable-length encoding genetic algorithm for solving multiobjective optimization problems. The proposed method is a binary implementation of the NSGA2 and it uses a Hash Table for storing all the solutions visited during algorithm evolution. This data structure makes possible to avoid the re-visitation of solutions and it provides recovering and storage of data with low computational cost. The algorithm memory is used for building crossover, mutation and local search operators with a parameterless variable-length encoding. These operators control the neighborhood based on the density of points already visited on the region of the new solution to be evaluated. Two classical multiobjective problems are used to compare two variations of the proposed algorithm and two variations of the binary NSGA2. A statistical analysis of the results indicates that the memory-based adaptive neighborhood operators are able to provide significant improvement of the quality of the Pareto-set approximations.
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