Knowledge Extraction and Problem Structure Identification in XCS

XCS has been shown to solve hard problems in a machine-learning competitive way. Recent theoretical advancements show that the system can scale-up polynomially in the problem complexity and problem size given the problem is a k-DNF with certain properties. This paper addresses two major issues in XCS: (1) knowledge extraction and (2) structure identification. Knowledge extraction addresses the issue of mining problem knowledge from the final solution developed by XCS. The goal is to identify most important features in the problem and the dependencies among those features. The extracted knowledge may not only be used for further data mining, but may actually be re-fed into the system giving it further competence in solving problems in which dependent features, that is, building blocks, need to be processed effectively. This paper proposes to extract a feature dependency tree out of the developed rule-based problem representation of XCS. The investigations herein focus on Boolean function problems. The extension to nominal and real-valued features is discussed.