Hierarchical State Machines

Hierarchical state machines are finite state machines whose states themselves can be other machines. In spite of their popularity in many modeling tools for software design, very little is known concerning their complexity and expressiveness. In this paper, we study these questions for hierarchical state machines as well as for communicating hierarchical state machines, that is, finite state machines extended with both hierarchy and concurrency. We present a comprehensive set of results characterizing (1) the complexity of the reachability, emptiness and universality problems, (2) the complexity of the language inclusion and equivalence problems, and (3) the succinctness relationships between different types of machines.

• Type: Conference
• Year: 2000
• Where: IFIPTCS
• Authors: Mihalis Yannakakis
• Keywords: Finite State Machines, Hierarchical State Machines, IFIPTCS 2000, State Machines, Theoretical Computer Science