Structured operational semantics for concurrency and hierarchy

Abstract

This paper presents a language, CHA, and semantics for studying Statechartslike drawings. CHA is a process algebra. CHA terms are interpreted as programs that extend Mealy- style finite automata with concurrent execution and hierarchical structure. Transitions in CHA can cross hierarchy boundaries, and it is this fact that makes giving a semantics to CHA (and to Statecharts) an interesting problem. In the terminology of [Mil89] all of the function symbols in CHA except the constants are static combinators.CHA is given an operational semantics in the Structural Operational Semantics (SOS) style of Plotkin [Plo81]. The Transition System Specification (TSS) methodology of [GV88] is employed, and the TSS presented is in the tyft/tyxt format from that paper. Conformance to the tyft/tyxt format has several benefits for analyzing CHA, the most important of which is that bisimulation is a congruence in the Labeled Transition System (LTS) C of the language.KeywordsInference RuleFunction SymbolOperational SemanticLabel Transition SystemProcess AlgebraThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.