UTP Semantics for Shared-State, Concurrent, Context-Sensitive Process Models

Process Modelling Language (PML) is a notationfor describing software development and business processes. It takes the form of a shared-state concurrent imperative language describing tasks asactivities that require resources to startand provide resources when they complete. Its syntax covers sequential composition, parallelism, iteration and choice, but without explicit iteration and choice conditions. It is intended to support a range of context-sensitive interpretations, from a rough guide for intended behaviour, to being very prescriptive about the order in which tasks must occur. We are using Unifying Theories of Programming (UTP) to modelthis range of semantic interpretations, with formal links between them, typically of the nature of a refinement. We address a number of challenges that arise when trying to developa compositional semantics for PML and its shared-state concurrent underpinnings, most notably in how UTP observations need to distinguishbetween dynamic state-changes and static context parameters. The formal semantics are intended as the basis for tool support for process analysis, with applicationsin the healthcare domain, covering such areas as healthcare pathwaysand software development and certification processesfor medical device software.