On Hierarchical Design of Computer Systems for Critical Applications.

We consider here the design of computer systems that must be trusted to satisfy simultaneously a variety of critical requirements such as human safety, fault tolerance, high availability, security, privacy, integrity, and timely responsiveness-and to continue to do so throughout maintenance and long-term evolution. Hierarchical abstraction provides the basis for successive layers of trust with respect to the full sel of critical requirements, explicitly reflecting differing degrees of criticality. [ABSTRACT FROM AUTHOR]