 He is the author of the book "Literature and Cognition", and was also editor of the book "Formal Theories of the Commonsense World".He led SRI's text-understanding research, and directed the development of the abduction-based TACITUS system for text understanding, and the FASTUS system for rapid extraction of information from text based on finite-state automata.The latter system constituted the basis for an SRI spinoff, Discern Communications.