Learning Classifier Systems: Looking Back and Glimpsing Ahead -- Knowledge Representations -- Analysis of Population Evolution in Classifier Systems Using Symbolic Representations -- Investigating Scaling of an Abstracted LCS Utilising Ternary and S-Expression Alphabets -- Evolving Fuzzy Rules with UCS: Preliminary Results -- Analysis of the System -- A Principled Foundation for LCS -- Revisiting UCS: Description, Fitness Sharing, and Comparison with XCS -- Mechanisms -- Analysis and Improvements of the Classifier Error Estimate in XCSF -- A Learning Classifier System with Mutual-Information-Based Fitness -- On Lookahead and Latent Learning in Simple LCS -- A Learning Classifier System Approach to Relational Reinforcement Learning -- Linkage Learning, Rule Representation, and the ?-Ary Extended Compact Classifier System -- New Directions -- Classifier Conditions Using Gene Expression Programming -- Evolving Classifiers Ensembles with Heterogeneous Predictors -- Substructural Surrogates for Learning Decomposable Classification Problems -- Empirical Evaluation of Ensemble Techniques for a Pittsburgh Learning Classifier System -- Applications -- Technology Extraction of Expert Operator Skills from Process Time Series Data -- Analysing Learning Classifier Systems in Reactive and Non-reactive Robotic Tasks.