Computing and Informatics

Conventional computation models assume symbolic representations of states and actions. Gurevich's ``Abstract-State Machine'' model takes a more liberal position: Any mathematical structure may serve as a state. This results in ``a computational model that is more powerful and more universal than standard computation models'' citeGur85. We characterize the Abstract-State Machine model as a special class of transition systems that widely extends the class of ``computable'' transition systems. This characterization is based on a fundamental Theorem of Y. Gurevich.