A Comparison Study on Rule Extraction from Neural Network Ensembles, Boosted Shallow Trees, and SVMs

One way to make the knowledge stored in an artificial neural network more intelligible is to extract symbolic rules. However,producing rules from Multilayer Perceptrons (MLPs) is an NP-hard problem. Many techniques have been introduced to generaterules from single neural networks, but very few were proposed for ensembles. Moreover, experiments were rarely assessed by10-fold cross-validation trials. In this work, based on the Discretized Interpretable Multilayer Perceptron (DIMLP), experimentswere performed on 10 repetitions of stratified 10-fold cross-validation trials over 25 binary classification problems. The DIMLParchitecture allowed us to produce rules from DIMLP ensembles, boosted shallow trees (BSTs), and Support Vector Machines(SVM). The complexity of rulesets was measured with the average number of generated rules and average number of antecedentsper rule. From the 25 used classification problems, the most complex rulesets were generated from BSTs trained by “gentle boosting”and “real boosting.” Moreover, we clearly observed that the less complex the rules were, the better their fidelity was. In fact, rulesgenerated from decision stumps trained by modest boosting were, for almost all the 25 datasets, the simplest with the highestfidelity. Finally, in terms of average predictive accuracy and average ruleset complexity, the comparison of some of our results to those reported in the literature proved to be competitive.