Evolutionary Computation - Advanced Artificial Intelligence - page 468

to his experiments, and drew some important conclusions and presented some
effective methods, which has produced prodigious influence on the application
and development of genetic algorithm.
The idea of genetic algorithm originates from biological evolution process. It
is essentially a class of stochastic search algorithm based on information genetic
mechanism and the principle of natural selection, including the principle of
adaptation, struggling for existence, in evolution process. In genetic algorithm, a
state space is expressed as a set of character strings. It is by applying probability
search process that genetic algorithm searches in state space and generates new
individuals. Comparison of genetic algorithm and natural evolution is presented
in Table 13.1.

Table 13.1 Comparison of genetic algorithm and natural evolution

natural evolution

genetic algorithm

Chromosome
gene
allele
locus
genotype
phenotype

character string
character, feature
feather value
location in a string
structure
parameter set, decoding Structure

The adaptation process is pivotal to artificial genetic systems. It generates a
new structure by a population's structures and genetic operations, such as
crossover and mutation, not by a simple structure. In a population, every
structure has its own fitness value, which is used to determine which structures
can generate new structures.
The most simple learning system based on genetic algorithm is shown in Fig.
13.1. The system consists of two subsystems. One is genetic algorithm-based
learning subsystem, which leads to proper change of structures. The other is
executive subsystem, which results in improvement of system's behaviors.
In 1988, Mayr had proposed neo-Darwinism, whose major viewpoints are as
follows (Mayr, 1988):

(1) An individual is a basic goal of selection;
(2) Stochastic process plays a great role in evolution, while most genetic
variations are accidental phenomena;
(3) Most genotypic variations, especially mutations, are the products of
recombination;