Strings - the Genetic Algorithm Solution

There are limits to the applicability of virtually every optimisation method. A GA may only be applied to a problem if it is possible to express the solution as a sequence of values. This sequence is referred to as a chromosome or a string, and each parameter within the chromosome is a gene. The entire set of genes constitutes the genotype, and the solution to which this genotype corresponds is known as the phenotype (Fig. 8). The GA works to refine strings with the help of the evolutionary operators outlined previously. 

GA strings are generally one-dimensional, but two-dimensional and higher-order strings have also been used where such a representation permits more 

The requirement that it be possible to represent the solution as a string is a necessary but not sufficient requirement for successful use of the GA, but when the problem has the appropriate structure, GAs may outperform conventional methods of solution by a significant margin. The characteristics that problems must display if the GA is to be an appropriate method to tackle them are discussed in most standard texts (see Further Reading). 

Other choices, beyond that of choosing binary or real-valued genes, may be available in the way in which the solution is represented and it is important that this be considered at an early stage. Just as the geometry of a molecule might be 

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