Perspectives on Complex Systems

Edward A. Lee
Dept. of Electrical Engineering and Computer Science
UC Berkeley

Friday, September 12th, 1997
Hogan Room, 531 Cory Hall
4:00-5:00 p.m.


Complete modeling of complex systems is not possible because of insufficient understanding, insufficient information, or insufficient computer cycles. This talk summarizes a study done under ISAT, the information science and technology board of DARPA. The study focused on the use of abstraction in modeling, designing, and understanding such systems. An abstraction is a model within a semantic framework, and the choice of semantic framework affects the ease of design, the modularity of a system, the ability to evolve a design, and the ability to understand properties such as security, robustness in the presense of faults, safety, and real-time performance. A rich variety of semantic frameworks have been developed over time, and no single one is adequate for understanding all important aspects of a complex system, so heterogeneous modeling is essential. This study identifies as a key research area systematic approaches to heterogeneity.