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Number 4 - December 2016
Volume 26 - 2016
The impatience mechanism as a diversity maintaining and saddle crossing strategy
Iwona Karcz-Duleba
Abstract
The impatience mechanism diversifies the population and facilitates escaping from a local optima trap by modifying fitness
values of poorly adapted individuals. In this paper, two versions of the impatience mechanism coupled with a phenotypic
model of evolution are studied. A population subordinated to a basic version of the impatience mechanism polarizes
itself and evolves as a dipole centered around an averaged individual. In the modified version, the impatience mechanism
is supplied with extra knowledge about a currently found optimum. In this case, the behavior of a population is quite
different than previously—considerable diversification is also observed, but the population is not polarized and evolves as
a single cluster. The impatience mechanism allows crossing saddles relatively fast in different configurations of bimodal
and multimodal fitness functions. Actions of impatience mechanisms are shown and compared with evolution without the
impatience and with a fitness sharing. The efficiency of crossing saddles is experimentally examined for different fitness
functions. Results presented in the paper confirm good properties of the impatience mechanism in diversity maintaining
and saddle crossing.
Keywords
phenotypic evolution, impatience operator without and with extra knowledge, polarization of population, maintaining population diversity, saddle crossing