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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

Estimation of distribution algorithms for clustering and classification

Cagnini, Henry Emanuel Leal 20 March 2017 (has links)
Submitted by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-06-29T11:51:00Z No. of bitstreams: 1 DIS_HENRY_EMANUEL_LEAL_CAGNINI_COMPLETO.pdf: 3650909 bytes, checksum: 55d52061a10460875dba677a9812fe9c (MD5) / Made available in DSpace on 2017-06-29T11:51:00Z (GMT). No. of bitstreams: 1 DIS_HENRY_EMANUEL_LEAL_CAGNINI_COMPLETO.pdf: 3650909 bytes, checksum: 55d52061a10460875dba677a9812fe9c (MD5) Previous issue date: 2017-03-20 / Extrair informa??es relevantes a partir de dados n?o ? uma tarefa f?cil. Tais dados podem vir a partir de lotes ou em fluxos cont?nuos, podem ser completos ou possuir partes faltantes, podem ser duplicados, e tamb?m podem ser ruidosos. Ademais, existem diversos algoritmos que realizam tarefas de minera??o de dados e, segundo o teorema do "Almo?o Gr?tis", n?o existe apenas um algoritmo que venha a solucionar satisfatoriamente todos os poss?veis problemas. Como um obst?culo final, algoritmos geralmente necessitam que hiper-par?metros sejam definidos, o que n?o surpreendentemente demanda um m?nimo de conhecimento sobre o dom?nio da aplica??o para que tais par?metros sejam corretamente definidos. J? que v?rios algoritmos tradicionais empregam estrat?gias de busca local gulosas, realizar um ajuste fino sobre estes hiper-par?metros se torna uma etapa crucial a fim de obter modelos preditivos de qualidade superior. Por outro lado, Algoritmos de Estimativa de Distribui??o realizam uma busca global, geralmente mais eficiente que realizar uma buscam exaustiva sobre todas as poss?veis solu??es para um determinado problema. Valendo-se de uma fun??o de aptid?o, algoritmos de estimativa de distribui??o ir?o iterativamente procurar por melhores solu??es durante seu processo evolutivo. Baseado nos benef?cios que o emprego de algoritmos de estimativa de distribui??o podem oferecer para as tarefas de agrupamento e indu??o de ?rvores de decis?o, duas tarefas de minera??o de dados consideradas NP-dif?cil e NP-dif?cil/completo respectivamente, este trabalho visa desenvolver novos algoritmos de estimativa de distribui??o a fim de obter melhores resultados em rela??o a m?todos tradicionais que empregam estrat?gias de busca local gulosas, e tamb?m sobre outros algoritmos evolutivos. / Extracting meaningful information from data is not an easy task. Data can come in batches or through a continuous stream, and can be incomplete or complete, duplicated, or noisy. Moreover, there are several algorithms to perform data mining tasks, and the no-free lunch theorem states that there is not a single best algorithm for all problems. As a final obstacle, algorithms usually require hyperparameters to be set in order to operate, which not surprisingly often demand a minimum knowledge of the application domain to be fine-tuned. Since many traditional data mining algorithms employ a greedy local search strategy, fine-tuning is a crucial step towards achieving better predictive models. On the other hand, Estimation of Distribution Algorithms perform a global search, which often is more efficient than performing a wide search through the set of possible parameters. By using a quality function, estimation of distribution algorithms will iteratively seek better solutions throughout its evolutionary process. Based on the benefits that estimation of distribution algorithms may offer to clustering and decision tree-induction, two data mining tasks considered to be NP-hard and NPhard/ complete, respectively, this works aims at developing novel algorithms in order to obtain better results than traditional, greedy algorithms and baseline evolutionary approaches.

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