We present the semantics of the dynamic hiding operator, which allows hiding new channels as they are acquired in a mobile network. However, silent channels cannot be moved out. Using dynamic hiding, we model the behaviour of a mobile telecommunications network Private Branch Exchange (PBX), which allows the network operator to lease some channels for private use.

We present a translation of CCS into CSP which is correct with respect to strong bisimulation. To our knowledge this is the first such translation to enjoy a correctness property. This contributes to the unification of the CCS and CSP families of concurrent calculi, in the spirit of Hoare and He’s unification programme through Unifying Theories of Programming. To facilitate this translation, we define CCSTau, the extension of CCS with visible synchronisation actions and the hiding operator. This separation of concerns between synchronisation and hiding turns out be sufficient to obtain our correct translation. Our translation, implemented in a Haskell prototype, makes it possible to use CSP-based verifiers such as FDR to reason about trace and failure (hence may- and must-testing) preorders for CCS processes.

Abstract In this paper, we present the denotational semantics for channel mobility in the Unifying Theories of Programming (UTP) semantics framework. The basis for the model is the UTP theory of reactive processes, precisely, the UTP semantics for Communicating Sequential Processes (CSP), which is extended to allow the mobility of channels—the set of channels that a process can use for communication (its interface), originally static or constant (set during the process's definition), is now made dynamic or variable: it can change during the process's execution. A channel is thus moved around by communicating it via other channels and then allowing the receiving process to extend its interface with the received channel. We introduce a new concept, thecapabilityof a process, which allows separating the ownership of channels from the knowledge of their existence. Mobile processes are then defined as having a static capability and a dynamic interface. Operations of a mobile telecommunications network, e.g., handover, load balancing, are used to illustrate the semantics. We redefine CSP operators and in particular provide the first semantics for the renaming and hiding operators in the context of channel mobility.