Down-Sampled Epsilon-Lexicase Selection for Real-World Symbolic Regression Problems

TL;DR

This paper introduces down-sampled epsilon-lexicase selection, combining subsampling with epsilon-lexicase to enhance symbolic regression performance, reducing diversity but significantly improving solution quality in real-world problems.

Contribution

The paper proposes a novel down-sampled epsilon-lexicase selection method and demonstrates its effectiveness over traditional methods in symbolic regression tasks.

Findings

Down-sampled epsilon-lexicase reduces population diversity.

It exhibits high hyperselection rates.

It improves solution quality by up to 85%.

Abstract

Epsilon-lexicase selection is a parent selection method in genetic programming that has been successfully applied to symbolic regression problems. Recently, the combination of random subsampling with lexicase selection significantly improved performance in other genetic programming domains such as program synthesis. However, the influence of subsampling on the solution quality of real-world symbolic regression problems has not yet been studied. In this paper, we propose down-sampled epsilon-lexicase selection which combines epsilon-lexicase selection with random subsampling to improve the performance in the domain of symbolic regression. Therefore, we compare down-sampled epsilon-lexicase with traditional selection methods on common real-world symbolic regression problems and analyze its influence on the properties of the population over a genetic programming run. We find that the diversity is reduced by using down-sampled epsilon-lexicase selection compared to standard epsilon-lexicase selection. This comes along with high hyperselection rates we observe for down-sampled epsilon-lexicase selection. Further, we find that down-sampled epsilon-lexicase selection outperforms the traditional selection methods on all studied problems. Overall, with down-sampled epsilon-lexicase selection we observe an improvement of the solution quality of up to 85% in comparison to standard epsilon-lexicase selection.