# IMPROVED COMPRESSED OBJECTIVE GENETIC ALGORITHM: COGA-II

### Kittipong Boonlong, Nachol Chaiyaratana, Kuntinee Maneeratana

#### Abstract

This paper presents an improved version of compressed objective genetic algorithm to solve problems with a large number of objectives. The improved compressed objective genetic algorithm (COGA-II) employs a rank assignment for the screening of non-dominated solutions that best approximate the Pareto front from vast numbers of available non-dominated solutions. Since the winning non-dominated solutions are heuristically determined from the survival competition, the procedure is referred to as a winning-score based ranking mechanism. In COGA-II, an m-objective vector is transformed to only one criterion, the winning score of which assignment is improved from that of the previous version, COGA. COGA-II is subsequently benchmarked against a non-dominated sorting genetic algorithm II (NSGA-II) and an improved strength Pareto genetic algorithm (SPEA-II), in seven scalable DTLZ benchmark problems. The results reveal that for the closeness to the true Pareto front COGA-II is much better than NSGA-II, and SPEA-II. For diversity of solutions, the diversity of the solutions by COGA-II is comparable to that of SPEA-II, while NSGA-II has poor diversity. COGA-II can also prevent solutions diverging from true Pareto solutions that occur on NSGA-II and SPEA-II for problems with more than 4 objectives. Thus, it can be concluded that COGA-II is suitable for solving an optimization problem with a large number of objectives.

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#### Paper Citation

#### in Harvard Style

Boonlong K., Chaiyaratana N. and Maneeratana K. (2010). **IMPROVED COMPRESSED OBJECTIVE GENETIC ALGORITHM: COGA-II** . In *Proceedings of the International Conference on Evolutionary Computation - Volume 1: ICEC, (IJCCI 2010)* ISBN 978-989-8425-31-7, pages 95-103. DOI: 10.5220/0003086700950103

#### in Bibtex Style

@conference{icec10,

author={Kittipong Boonlong and Nachol Chaiyaratana and Kuntinee Maneeratana},

title={IMPROVED COMPRESSED OBJECTIVE GENETIC ALGORITHM: COGA-II},

booktitle={Proceedings of the International Conference on Evolutionary Computation - Volume 1: ICEC, (IJCCI 2010)},

year={2010},

pages={95-103},

publisher={SciTePress},

organization={INSTICC},

doi={10.5220/0003086700950103},

isbn={978-989-8425-31-7},

}

#### in EndNote Style

TY - CONF

JO - Proceedings of the International Conference on Evolutionary Computation - Volume 1: ICEC, (IJCCI 2010)

TI - IMPROVED COMPRESSED OBJECTIVE GENETIC ALGORITHM: COGA-II

SN - 978-989-8425-31-7

AU - Boonlong K.

AU - Chaiyaratana N.

AU - Maneeratana K.

PY - 2010

SP - 95

EP - 103

DO - 10.5220/0003086700950103