Slicing Hierarchical Automata for Model Checking UML Statecharts

Hierarchical Automata has been widely used in modeling dynamic aspects of reactive software, such as in UML Statecharts. At the same time, model checking is an automatic technique to ensure the correctness of software models, where state space explosion is the main obstacle to applying this technique in large scale applications. The paper presents a method for slicing hierarchical automata with respect to properties to be verified. The considered formalism is Extended Hierarchical Automata (EHA), in which a set of dependence relations is specified after analyzing characteristics such as hierarchy, concurrency and synchronization. We present the algorithm of slicing EHA based on the slicing criterion in terms of states and transitions. The algorithm can remove the hierarchies and concurrent states which are irrelevant to the property, and reduce the state space efficiently in model checking UML Statecharts.