|Advisor:||Edward A. Lee|
Hierarchical concurrent FSMs (HCFSMs) increase the usefulness of FSMs by extending them with structuring and communication mechanisms. However, most formalisms that support HCFSMs, such as Statecharts and its variants, tightly integrate the concurrency semantics with the FSM semantics. Based on the Ptolemy philosophy of hierarchical composition of heterogeneous models of computation, the *charts formalism  allows embedding hierarchical FSMs within various concurrency models, in particular continuous time, dataflow, discrete event and synchronous/reactive models. In this heterogeneous model, the semantics of FSM, concurrency and hierarchy are naturally supported. Our scheme decouples the FSM from the concurrency models, enabling selection of the most appropriate concurrency model for the problem at hand.
An FSM domain has been developed in Ptolemy II and is integrated with the CT, DE, SDF, and Giotto domains. We are currently working on integrating the FSM domain with process-based domains such as CSP and PN. We will also investigate what formal verification methods can be applied to the *charts formalism.
Last updated 11/18/02