An old-fashioned recipe for real time

Abstract

Traditional methods for specifying and reasoning about concurrent systems work for real-time systems. Using TLA (the temporal logic of actions), we illustrate how they work with the examples of a queue and of a mutual-exclusion protocol. In general, two problems must be addressed: avoiding the real-time programming version of Zeno's paradox, and coping with circularities when composing real-time assumption/guarantee specifications. Their solutions rest on properties of machine closure and realizability.