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Application of Genetic Algorithm in Multi-objective Optimization

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problem. Some strategy parameters (variances and covariance <strong>of</strong> <strong>in</strong>dividuals) are used to direct the<br />

actions <strong>of</strong> the mutation operator. Mutation operator acts on the strategy parameters first and then<br />

the object variables are mutated us<strong>in</strong>g the probability distribution generated from the mutated<br />

strategy parameters. With these self-adapted strategy parameters and determ<strong>in</strong>istic selection process,<br />

ESs evolve to optimal solution and stop when any stopp<strong>in</strong>g criteria are met. Though only one<br />

application <strong>of</strong> ESs has mentioned <strong>in</strong> computational chemistry [11], they have the potential to be an<br />

alternative to GAs, especially <strong>in</strong> parameter optimization.<br />

2.1.2.3 Evolutionary Programm<strong>in</strong>g (EP):<br />

In EP, limited symbolic alphabets are used to represent the f<strong>in</strong>ite state mach<strong>in</strong>es. It was first<br />

developed by Fogel et al. [12] and later modified by D. B. Fogel to represent real numbers [6].<br />

Though it deals with a str<strong>in</strong>g <strong>of</strong> real numbers similar to ESs, the ma<strong>in</strong> difference between them is<br />

that EP does not use any recomb<strong>in</strong>ation operator. Thus, the convergence to better solution depends<br />

only on mutation operator by us<strong>in</strong>g Gaussian probability distribution. EP is suitable for parameter<br />

optimization and has been applied <strong>in</strong> some other areas too [13, 14].<br />

2.1.2.4 <strong>Genetic</strong> Programm<strong>in</strong>g (GP):<br />

Individuals are embodied as computer programs <strong>in</strong> GP. Based on a given problem, GP generates<br />

computer program automatically to solve that problem. Here, a computer program is encoded as<br />

chromosome and evaluated to measure its fitness to meet predef<strong>in</strong>ed <strong>objective</strong>s or goals. It is also<br />

considered as an application <strong>of</strong> GAs for problems hav<strong>in</strong>g computer programs as the <strong>in</strong>dividuals. In<br />

1985, Cramer [15] first developed the modern “Tree-based” GP where programm<strong>in</strong>g languages are<br />

organized <strong>in</strong> tree-based arrangements and modified us<strong>in</strong>g various GA operators. Koza [16] showed<br />

its application <strong>in</strong> various complex optimization problems along with <strong>in</strong> model<strong>in</strong>g DNA expression.<br />

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