A Study on DNA Coding Method and Knowledge Discovery

名古屋大学Nagoya University博士(工学)A new coding method for GA based on the biological DNA, called the DNA coding method, and a mechanism of development from the artificial DNA have been proposed in this thesis. The DNA coding method and the mechanism of development from the artificial DNA are suitable for knowledge representation. One of the features of this method is that the length of the proposed DNA chromosome is variable and it is easy to insert and delete parts of chromosomes. By these features, various operations including virus and enzyme operations can be applied easily with no constraint. Another feature of the proposed coding method is that this method has redundancy and overlapping of genes, and this flexible coding works well so that genes survive far beyond the life time of individuals. This method was combined with the PBGA. This combination of the DNA coding method with the PBGA accelerates the knowledge discovery process. The summarized results obtained in this thesis are as follows: In Chapter 2, the flow of development from the DNA chromosome, the genetic operations including virus and enzyme operations, and the features of the DNA coding method were described. The new coding method uses the four bases of DNA, and the way of development from DNA to a set of fuzzy rules is a simple analogy of development of biological DNA. The DNA chromosome has many redundant parts, and allows overlapped representation of genes. This DNA chromosome compresses information by the overlapping of genes. Length of the DNA chromosome is variable, and it has no constraint on genetic operations. The virus and enzyme operations also have no difficulty to apply because it is easy to insert and delete strands of strings from the DNA chromosomes. In chapter 3, the DNA coding method was combined with the PBGA. The biological bacteria can transfer its own DNA from male cells to female cells through transfer of F factor. New bacteria whose parts of DNA are mutated when reproduction has occurred are tested in the environment, and the bacteria which can adapt themselves to the environment best can survive. By these process, the characteristics of more adaptable bacteria can be spread among the entire bacteria population. The PBGA utilizes mechanisms of genetic recombination in bacterial genetics. The PBGA is simple and very efficient in improving local portions of chromosomes. Genes are reproduced and tested, and the elite genes are transferred to the chromosomes. The PBGA can be combined with the DNA coding method easily and accelerates the knowledge discovery process. Chapter 4 described the problem formulation for knowledge discovery, which was a discovery of effective fuzzy control rules using the DNA coding method. The concrete ways of genetic operations including virus, enzyme, and bacterial operations were also presented. These fuzzy rules are used to control mobile robots. The simulation conditions and the performance of two robots which play chasing and avoiding were described in this chapter. The robot which performs well with a set of fuzzy rules receives more payoffs from the environment. Considering these payoffs as fitness values, the genetic operations are applied to the chromosomes, and the fuzzy rules are evolved. This chapter defined the flow of translation from the DNA chromosome and the correspondence between amino acids and the parameters. One gene which starts from a start codon corresponds to one fuzzy rule. The virus and enzyme operations are applied in the simple way by inserting or deleting a part of a chromosome. The bacterial operation is also applied to fuzzy rules. After this bacterial operation to all of the chromosomes, the conventional genetic operations are applied to the population of chromosomes by regarding the payoffs of the robots as their fitness values. Chapter 5 showed the effectiveness of the proposed DNA coding method and the genetic operations described in the previous chapter. Simulations of competitions between the chasing robots and the avoiding robots were done. The effectiveness of this method and the virus, enzyme, and bacterial operations was shown. The performance of this method and these operations showed better result than that of the conventional method and those without these operations. The effects of changes of genes by the bacterial operation were studied in this chapter. The small change of a gene could cause a drastic improvement in the performance of robots. The effectiveness of redundancy and overlapping of genes realized by the proposed method was also shown in this chapter. The redundancy and overlapping of genes worked well so that genes survive far beyond the life time of individuals. The results showed that durations of chromosomes were shorter than long lived genes. The disappearance of chromosomes did not mean the disappearance of genes. Forthermore, many genes were activated again after long inactive time. These genes were kept in chromosomes, even though they did not work.名古屋大学博士学位論文 学位の種類:博士(工学) (課程) 学位授与年月日:平成9年3月25日doctoral thesi

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