Application of Genetic Algorithm in Multi-objective Optimization
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2. The solution is strictly better than <strong>in</strong> at least one <strong>objective</strong>, or mathematically, ) ⊲<br />
) for at least one ∈1,2,3,….,M<br />
The dom <strong>in</strong>ance relation does not have reflexive property as no solution dom<strong>in</strong>ates itself. It also<br />
does not exhibit symmetric characteristic as the dom<strong>in</strong>ance <strong>of</strong> one solution x over another solution y<br />
does not mean the dom<strong>in</strong>ance <strong>of</strong> y over x. If x dom<strong>in</strong>ates y and y dom<strong>in</strong>ates z (a third solution),<br />
then x dom<strong>in</strong>ates z which shows the transitive property <strong>of</strong> the dom<strong>in</strong>ance relation.<br />
<br />
Pareto-Optimal Set (Non-dom<strong>in</strong>ated set):<br />
A set is said to be a non-dom<strong>in</strong>ated set or Pareto-optimal set if it is not dom<strong>in</strong>ated by any other<br />
solution that belongs to the solution set. The Pareto-optimal set is the best optimal solution for all<br />
<strong>objective</strong> functions and cannot be improved with respect to one <strong>objective</strong> by worsen<strong>in</strong>g another<br />
one. Mathematically, if P is a set <strong>of</strong> solutions, the non-dom<strong>in</strong>ated set <strong>of</strong> solutions P * comprises those<br />
solutions which are not dom<strong>in</strong>ated by any member <strong>of</strong> the set P. The non-dom<strong>in</strong>ated set <strong>of</strong> solutions<br />
can be generated by compar<strong>in</strong>g all possible pairs <strong>of</strong> a given solution set and determ<strong>in</strong><strong>in</strong>g which<br />
solutions dom<strong>in</strong>ate which, and which are not dom<strong>in</strong>ated by each other. The Pareto-optimal set, P *<br />
can be written as:<br />
∗ ∈ | ∃ ∈ ≼ <br />
Pareto-optimal sets are called global when the set <strong>of</strong> solutions, P, is the entire search space. If for<br />
every member x <strong>in</strong> a set P, there exist no solutions y <strong>in</strong> the neighborhood <strong>of</strong> x, then‖‖ ,<br />
dom<strong>in</strong>at<strong>in</strong>g any member <strong>of</strong> the set, then P establishes a locally Pareto-optimal set.<br />
<br />
Pareto-front:<br />
The Pareto-front conta<strong>in</strong>s the values <strong>of</strong> <strong>objective</strong> functions for all solutions <strong>in</strong> the Pareto-optimal set<br />
<strong>in</strong> the <strong>objective</strong> space. If the Pareto-front is ∗ for a given MOOP hav<strong>in</strong>g <strong>objective</strong> function F(x),<br />
then mathematically:<br />
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