Professor Emeritus, Computer Science and Philosophy, University of Texas at Austin. 2008- (Note: The UT Department of Computer Sciences has changed its name to Computer Science, singular.)

Professor in Computer Sciences, Mathematics, and Philosophy Departments
University of Texas at Austin, 1981-2008.

Senior Computing Research Scientist, Fall 1993 - Spring 1995,
Computational Logic, Inc.
Austin, Texas

Senior Member of Technical Staff, 1985-1987
Microelectronics and Computer Technology Corporation
Artificial Intelligence Program
Austin, Texas

Associate Professor, 1981-1985
Computer Sciences Department,
University of Texas at Austin

Staff Scientist, 1981
Senior Research Mathematician, 1979-81
Research Mathematician, 1973-78
Computer Science Laboratory
SRI International
Menlo Park, California

Research Fellow, 1971-73
Department of Computational Logic
University of Edinburgh, Edinburgh, Scotland

Research Assistant, 1970-71
Artificial Intelligence Laboratory
Massachusetts Institute of Technology, Cambridge, Mass.

Teaching Assistant, 1967-70
Department of Mathematics
University of Texas, Austin, Texas