Alternative Bloat Control Methods

Bloat control is an important aspect of evolutionary computation methods, such as genetic programming, which must deal with genomes of arbitrary size. We introduce three new methods for bloat control: Biased Multi-Objective Parsimony Pressure (BMOPP), the Waiting Room, and Death by Size. These methods are unusual approaches to bloat control, and are not only useful in various circumstances, but two of them suggest novel approaches to attack the problem. BMOPP is a more traditional parsimony-pressure style bloat control method, while the other two methods do not consider parsimony as part of the selection process at all, but instead penalize for parsimony at other stages in the evolutionary process. We find parameter settings for BMOPP and the Waiting Room which are effective across all tested problem domains. Death by Size does not appear to have this consistency, but we find it a useful tool as it has particular applicability to steady-state evolution.