An Exploration of Exploration: Measuring the ability of lexicase selection to find obscure pathways to optimality
Jose Guadalupe Hernandez, Alexander Lalejini, Charles Ofria

TL;DR
This paper introduces an exploration diagnostic to evaluate how different lexicase selection variants influence search space exploration, revealing insights into their effectiveness and guiding future algorithm design.
Contribution
It develops a diagnostic tool for measuring exploration capacity and applies it to analyze lexicase variants, providing new understanding of their exploratory behaviors.
Findings
Lexicase selection out-explores tournament selection.
Relaxing lexicase with epsilon improves exploration.
Down-sampling and cohort methods affect exploration differently.
Abstract
Parent selection algorithms (selection schemes) steer populations through a problem's search space, often trading off between exploitation and exploration. Understanding how selection schemes affect exploitation and exploration within a search space is crucial to tackling increasingly challenging problems. Here, we introduce an "exploration diagnostic" that diagnoses a selection scheme's capacity for search space exploration. We use our exploration diagnostic to investigate the exploratory capacity of lexicase selection and several of its variants: epsilon lexicase, down-sampled lexicase, cohort lexicase, and novelty-lexicase. We verify that lexicase selection out-explores tournament selection, and we show that lexicase selection's exploratory capacity can be sensitive to the ratio between population size and the number of test cases used for evaluating candidate solutions.…
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Taxonomy
TopicsIdentification and Quantification in Food · HIV Research and Treatment · Advanced biosensing and bioanalysis techniques
