A Veri cation Calculus for the TAO Coordination Model

The TAO coordination model combines logical concepts and concurrency mechanisms: a set of processes cooperate via a common, content addressable, shared state. Computation and communication are achieved through queries and updates of the common store, the basic statements in this paradigm. A query checks whether some information is or is not entailed by the store, and an update changes the contents of the store, possibly in a non-monotonic way. We propose a calculus to support the development of systems in this model, based on as-sertional reasoning and on the deenition of an axiomatic semantics in the weakest precondition style, the speciication language being rst order temporal logic.