The principal investigator's approach is to study problems in the management of data in the CAD design process. In previous NSF- supported research, the proposer has implemented a prototype version server for computer-aided design (CAD) data. He plans to use this as an operational testbed in which to investigate how to apply and implement object-oriented and logic-programming concepts, such as prototypical objects, inheritance, and inference, within the CAD environment. Dr. Katz plans to investigate two problems: (1) new ways to propagate data through a lattice of interrelated design objects; and (2) extend some recent work, applying inference techniques to validate design correctness, to the problem of controlling constraint and change propagation. VLSI (very large scale integration) is a recent field that explores how to design highly complex integrated circuits and related electronic systems. Development of the field is important to the nation's competitive lead in electronics. The proposed research is in CAD design management, a subject that is of exceptional importance to the CAD industry. Traditional database techniques are not adequate to support today's CAD design process. This research addresses the need to carefully manage the many information details which are typically produced during the CAD process. Such research is needed to promote automation in the CAD field, where design of very and ultra large scale integrated (VLSI/ULSI) circuits is now so complex that humans cannot effectively deal with them. The principal investigator has made important contributions to the CAD design management area. He brings to bear a useful blend of theoretical and practical talents.