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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Uma implementa??o paralela h?brida para o problema do caixeiro viajante usando algoritmos gen?ticos, GRASP e aprendizagem por refor?o

Santos, Jo?o Paulo Queiroz dos 06 March 2009 (has links)
Made available in DSpace on 2014-12-17T14:55:11Z (GMT). No. of bitstreams: 1 JoaoPQS.pdf: 1464588 bytes, checksum: ad1e7b6af306b0ce9b1ccb1fb510c4ab (MD5) Previous issue date: 2009-03-06 / The metaheuristics techiniques are known to solve optimization problems classified as NP-complete and are successful in obtaining good quality solutions. They use non-deterministic approaches to generate solutions that are close to the optimal, without the guarantee of finding the global optimum. Motivated by the difficulties in the resolution of these problems, this work proposes the development of parallel hybrid methods using the reinforcement learning, the metaheuristics GRASP and Genetic Algorithms. With the use of these techniques, we aim to contribute to improved efficiency in obtaining efficient solutions. In this case, instead of using the Q-learning algorithm by reinforcement learning, just as a technique for generating the initial solutions of metaheuristics, we use it in a cooperative and competitive approach with the Genetic Algorithm and GRASP, in an parallel implementation. In this context, was possible to verify that the implementations in this study showed satisfactory results, in both strategies, that is, in cooperation and competition between them and the cooperation and competition between groups. In some instances were found the global optimum, in others theses implementations reach close to it. In this sense was an analyze of the performance for this proposed approach was done and it shows a good performance on the requeriments that prove the efficiency and speedup (gain in speed with the parallel processing) of the implementations performed / As metaheur?sticas s?o t?cnicas conhecidas para a resolu??o de problemas de otimiza??o, classificados como NP-Completos e v?m obtendo sucesso em solu??es aproximadas de boa qualidade. Elas fazem uso de abordagens n?o determin?sticas que geram solu??es que se aproximam do ?timo, mas no entanto, sem a garantia de que se encontre o ?timo global. Motivado pelas dificuldades em torno da resolu??o destes problemas, este trabalho prop?s o desenvolvimento de m?todos paralelos h?bridos utilizando a aprendizagem por refor?o e as metaheur?sticas GRASP e Algoritmos Gen?ticos. Com a utiliza??o dessas t?cnicas em conjunto, objetivou-se ent?o, contribuir na obten??o de solu??es mais eficientes. Neste caso, ao inv?s de utilizar o algoritmo Q-learning da aprendizagem por refor?o, apenas como t?cnica de gera??o das solu??es iniciais das metaheur?sticas, este tamb?m aplicado de forma cooperativa e competitiva com o Algoritmo Gen?tico e o GRASP, em uma implementa??o paralela. Neste contexto, foi poss?vel verificar que as implementa??es realizadas neste trabalho apresentaram resultados satisfat?rios, tanto na parte de coopera??o e competi??o entre os algoritmos Q-learning, GRASP a Algoritmos Gen?ticos, quanto na parte de coopera??o e competi??o entre grupos destes tr?s algoritmos. Em algumas inst?ncias foi encontrado o ?timo global; quando n?o encontrado, conseguiu-se chegar bem pr?ximo de seu valor. Neste sentido foi realizada uma an?lise do desempenho da abordagem proposta e verificou-se um bom comportamento em rela??o aos quesitos que comprovam a efici?ncia e o speedup (ganho de velocidade com o processamento paralelo) das implementa??es realizadas

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