The Temporal Specification and Verification of Real-Time Systems

We extend the specification language of temporal logic, the corresponding verification framework, and the underlying computational model to deal with real-time properties of reactive systems.

• Semantics We introduce the abstract computational model of timed transition systems as a conservative extension of traditional transition systems: qualitative fairness requirements are superseded by quantitative real-time constraints on the transitions. Digital clocks are introduced as observers of continuous real-time behavior. We justify our semantical abstractions by demonstrating that a wide variety of concrete real-time systems can be modeled adequately.

• Specification We present two conservative extensions of temporal logic that allow for the specification of timing constraints: while timed temporal logic provides access to time through a novel kind of time quantifier, metric temporal logic refers to time through time-bounded versions of the temporal operators. We justify our choice of specification languages by developing a general framework for the classification of real-time logics according to their complexity and expressive power.

• Verification We develop tools for determining if a real-time system that is modeled as a timed transition system meets a specification that is given in timed temporal logic or in metric temporal logic. We present both model-checking algorithms for the automatic verification of finite-state real-time systems and proof methods for the deductive verification of real-time systems. Both techniques are conservative generalizations of the corresponding conventional approaches to program verification, which abstract time from consideration.

Ph.D. Thesis, Technical Report STAN-CS-91-1380, Stanford University, August 1991, 272 pages.