• [Sept 1998 - present] Lecturer in Computer Science, California Institute of Technology, Pasadena, California.
• [Sept 1996 - present] Senior Scientist, Department of Electrical Engineering, California Institute of Technology, Pasadena, California.
• [Sept 1995 - June 1996] Instructor, Department of Computer Science, University of California, Los Angeles.
• [Feb 1994 - Dec 1994] Visiting Researcher, Division of Neurosurgery, School of Medicine, and Computer Science Department, University of California, Los Angeles
• [Sept 1992-Jan 1994] Member of Technical Staff, Computer Systems Research Department, The Aerospace Corporation, Los Angeles
• [Feb-Aug 1992] Sony Sabbatical Chair, Sony Computer Science Research Laboratory, Tokyo
• [1985-1991] Principal Development Engineer, University of California, Los Angeles
• [1983-5] Senior Research Scientist, Electrical Engineering Systems Department, University of Southern California, Los Angeles
• [1982] Visiting Research Professor, Image Processing Institute, University of Southern California, Los Angeles
• [1969 - 1984] Lecturer (Corresponds to Assistant and Associate Professor) in Computer Science, Queen Mary College, London University (tenured from 1973)
• [1968-9] Acting Assistant Professor, Engineering Department, UCLA, Los Angeles
• [1967-8] Visiting Assistant Professor, Computer Science Department, Carnegie-Mellon University, Pittsburgh
• [1966-7] Research Scientist, Computer Science Department, Carnegie Institute of Technology, Pittsburgh
• [1966] Research Assistant in Computing Methods, Mathematics Department, Royal Holloway College, London University

Visiting Posts

• [Summer 1981] Engineer, Naval Ocean Systems Center, San Diego
• [Summer 1980] Visiting Researcher, Computer Science Department, Carnegie-Mellon University, Pittsburgh
• [Summer 1973] Visiting Lecturer, Mackerere University, Kampala, Uganda
• Esprit DAI project IMAGINE 1991 Logic Programming Group, Imperial College, London, PI: Keith Clark.