Representing hierarchical state machine models in SMT-LIB

Abstract

We motivate and present a proposal for how to represent the syntax of behavioural models written in extended finite-state machine languages with hierarchical states (e.g., the Statecharts family) in SMT-LIB. By including the state structure explicitly in the SMT-LIB model, our goal is to facilitate effective automated deductive reasoning, which can exploit the structure found in the state hierarchy. We present a novel method that combines deep and shallow encoding techniques to describe models that have both state hierarchy and use the rich datatypes found in SMT-LIB. Our representation permits varying semantics to be chosen for the syntax recognizing the rich variety of semantics that exist for this family of modelling languages. We hope that discussion of these representation issues will facilitate model sharing for investigation of analysis techniques.