2004 Volume 17 Issue 7 Pages 278-287
One advantage of evolutionary multiobjective optimization (EMO) algorithms over classical approaches is that many non-dominated solutions can be simultaneously obtained by their single run. This paper shows how this advantage can be utilized in genetic rule selection for the design of fuzzy rule-based classification systems. Our genetic rule selection is a two-stage approach. In the first stage, a pre-specified number of candidate rules are extracted from numerical data using a data mining technique. In the second stage, an EMO algorithm is used for finding non-dominated rule sets with respect to three objectives. Since one of the three objectives is to maximize a classification rate on training patterns, the evolution of rule sets tends to overfit to training patterns. The question is whether the other two objectives with respect to complexity work as a safeguard against the over-fitting. In this paper, we examine the effect of the three-objective formulation on the generalization ability of obtained rule sets through computational experiments where many non-dominated rule sets are generated using an EMO algorithm for a number of high-dimensional pattern classification problems. Finally, we demonstrate that an ensemble of generated fuzzy rule-based systems leads to high generalization ability.
