Ralf Hartmut Guting is Professor of computer science at the University of Hagen, Germany. After a one-year visit to the IBM Almaden Research Center in 1985, extensible and spatial database systems became his major research interests. He is the author of two German textbooks on data structures/algorithms and on compilers and has published about 50 articles on computational geometry and database systems. He is an associate editor of ACM Transactions on Database Systems.