An Automata-Theoretic Approach to Reasoning about Infinite-State Systems

We develop an automata-theoretic framework for reasoning about infinitestate sequential systems. Our framework is based on the observation that states of such systems, which carry a finite but unbounded amount of information, can be viewed as nodes in an infinite tree, and transitions between states can be simulated by finite-state automata. Checking that the system satisfies a temporal property can then be done by an alternating two-way tree automaton that navigates through the tree. As has been the case with finite-state systems, the automatatheoretic framework is quite versatile. We demonstrate it by solving several versions of the model-checking problem for -calculus specifications and prefixrecognizable systems, and by solving the realizability and synthesis problems for -calculus specifications with respect to prefix-recognizable environments.