Dr. Hirtle is Professor Emeritus in the School of Computing and Information at the University of Pittsburgh. He has held positions as chair of the Department of Information Science and Telecommunications, joint appointments in the Department of Psychology and Intelligent Systems Program. In addition, he was the founding co-editor of Spatial Cognition and Computation, past-president of the Classification Society of North America and Book Review Editor of the Journal of Classification. He has had visiting appointments in the Department of Geoinformation at the Technical University of Vienna in Austria and the Department of Computer Science at Molde College in Norway. He hosted the Third International Conference on Spatial Information Theory (COSIT'97), in the Laurel Highlands, outside of Pittsburgh, PA, in October of 1997 and co-chaired the NCGIA/Varenius Panel on "Cognitive Models of Dynamic Phenomena and Their Representations" in October of 1998 with Alan MacEachren.Specialties: He directed the Spatial Information Research Group at the University of Pittsburgh, which conducted research on the structure of cognitive maps, navigation in hypertext, and models for spatial cognition.