Title:
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Improving Convergence, Diversity and Pertinency in Multiobjective Optimisation
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Real-world problems commonly require the simultaneous consideration of multiple, often
conflicting, objectives. Solving a multiobjective optimisation problem (MOP) is concerned with
finding an ideal set of tradeoff solutions which are close to and uniformly distributed across the
optimal tradeoff surface. Convergence and diversity are thus essential requirements .of
multiobjective optimisers, which are sometimes also required to focus on pertinent areas of the
search space. Evolutionary computation (EC) techniques are stochastic, population-based, global
search techniques well suited for solving MOPs. However, EC techniques can often involve a
large number of objective function calculations which can make the convergence towards optimal
tradeoff surfaces computationally expensive. Additionally, in the evolutionary multiobjective
optimization community, the bi-objective case is the most heavily studied. Conclusions drawn
from such low-dimensional frameworks used to be generalized for all problems' dimensions.
Research, however, has shown that high-dimensional problems (> 3 objectives) can possess
different characteristics. One of the most important challenges faced in such optimisation
scenarios is the conflict between convergence and diversity of solutions.
In this study, new approaches are proposed for enhancing the convergence and diversification
capacities of so~e of the best multiobjective evolutionary optimisers (MOEAs). The inclusion of
quality metrlcs as indicators is implemented as an approach for solving the conflict between
solutions' convergence and diversity in high-dimensional optimisation problems. Moreover, a
convergence acceleration technique for MOEAs which exploits the objective space, where the
goal and objectives lies,is devised and assessed. In the final part of the study, some established
progressive preference articulation techniques are examined, and their utility for tackling MOPs
is discussed from the viewpoint of the decision maker. Progressive preference articulation
techniques are effective methods for supporting the decision maker in guiding the search into
pertinent regions of interest and coping with the curse of dimensionality.
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