This edition of a pioneering biomedical informatics text has been radically reorganized for courses that go beyond standard introductory material. It includes exercises, project ideas, and new topics such as tree-structured data, interval trees, and time-oriented medical data and their use; On Line Application Processing (OLAP); nursing knowledge and advice in a rule-based system; X-ray physics and algorithms for image reconstruction; Introduction to Markov processes; Fundamental elements of hospital IT security. It describes core research concepts of biomedical data and knowledge representation, information access, decision-making, information and technology in biomedical contexts and is a teaching reference. It includes example programs in Common LISP. It also includes humor, history, and anecdotal material to balance the mathematically and computationally intensive development of many topic—and emphasizes ideas and methods of potentially lasting value. Ira Kalet is Professor Emeritus of Radiation Oncology and Biomedical Informatics and Medical Education, University of Washington. He was an adjunct professor in Computer Science and Engineering and Biological Structure. He was IT Security Director for the University of Washington School of Medicine. He is a member of the American Medical Informatics Association and a Fellow of the American College of Medical Informatics. His research interests include simulation systems in radiation treatment of cancer, software development methodology, and artificial intelligence applications in medicine. The book develops principles and methods for representing biomedical data; offers principles for expressing biomedical data and ideas in computable form; and discusses user interfaces, interactive graphics, and knowledge resources and reference material on programming languages.