The impatience mechanism as a diversity maintaining and saddle crossing strategy

• Main Author: Karcz-Duleba Iwona
• Format: Article
• Language: English
• Published: Sciendo 2016-12-01
• Series: International Journal of Applied Mathematics and Computer Science
• Subjects: phenotypic evolution; impatience operator without and with extra knowledge; polarization of population; maintaining population diversity; saddle crossing
• Online Access: https://doi.org/10.1515/amcs-2016-0064

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.