Principles of Data Mining and Knowledge Discovery : Third European Conference PKDD99 Prague Czech Republic September 15 18 1999 Proceedings This book constitutes the refereed proceedings of the Third European Conference on Principles and Practice of Knowledge Discovery in Databases PKDD99 held in Prague Czech Republic in September 1999. The 28 revised full papers and 48 poster presentations were carefully reviewed and selected from 106 full papers submitted. The papers are organized in topical sections on time series applications taxonomies and partitions logic methods distributed and multirelational databases text mining and feature selection rules and induction and interesting and unusual issues