An Observational Theory for Mobile Ad Hoc Networks

AbstractWe propose a process calculus to study the observational theory of Mobile Ad Hoc Networks. The operational semantics of our calculus is given both in terms of a Reduction Semantics and in terms of a Labelled Transition Semantics. We prove that the two semantics coincide. The labelled transition system is then used to derive the notions of simulation and bisimulation for ad hoc networks. As a main result, we prove that the (weak) labelled bisimilarity completely characterises (weak) reduction barbed congruence, a standard, branching-time, contextually-defined program equivalence. We then use our (bi)simulation proof methods to formally prove a number of non-trivial properties of ad hoc networks

On Expressiveness and Behavioural Theory of Attribute-based Communication

Attribute-based communication is an interesting alternative to broadcast and binary communication when providing abstract models for the so called Collective Adaptive Systems which consist of a large number of interacting components that dynamically adjust and combine their behavior to achieve specifc goals. A basic process calculus, named AbC, is introduced whose primary primitive for interaction is attribute-based communication. An AbC system consists of a set of parallel components each of which is equipped with a set of attributes. Communication takes place in an implicit multicast fashion, and interactions among components are dynamically established by taking into account\connections" as determined by predicates over the attributes exposed by components. First, the syntax and the semantics of AbC are presented, then expressiveness and effectiveness of the calculus are demonstrated both in terms of the ability to model scenarios featuring collaboration, reconfiguration, and adaptation and of the possibility of encoding a process calculus for broadcasting channel-based communication and other communication paradigms. Behavioral equivalences for AbC are introduced for establishing formal relationships between different descriptions of the same system

Towards a Primitive Higher Order Calculus of Broadcasting Systems

Ethernet-style broadcast is a pervasive style of computer communication. In this style, the medium is a single nameless channel. Previous work on modelling such systems proposed a first order process calculus called CBS. In this paper, we propose a fundamentally different calculus called HOBS. Compared to CBS, HOBS 1) is higher order rather than first order, 2) supports dynamic subsystem encapsulation rather than static, and 3) does not require an "underlying language" to be Turing-complete. Moving to a higher order calculus is key to increasing the expressivity of the primitive calculus and alleviating the need for an underlying language. The move, however, raises the need for significantly more machinery to establish the basic properties of the new calculus. This paper develops the basic theory for HOBS and presents two example programs that illustrate programming in this language. The key technical underpinning is an adaptation of Howe\u27s method to HOBS to prove that bisimulation is a congruence. From this result, HOBS is shown to embed the lazy λ-calculus