Value passing for Communicating Piecewise Deterministic Markov Processes

In this paper we extend the CPDP model, which is used for compositional specification of PDP-type stochastic hybrid systems, to the value passing CPDP model. With value passing we can express communication of values of continuous variables between CPDP components. We show that the class of value passing CPDPs is closed under composition. We illustrate the use of value passing CPDPs by modelling an Air Traffic Management system as a network of interacting value passing CPDPs.

State-based and process-based value passing

State-based and process-based formalisms each come with their own distinct set of assumptions and properties. To combine them in a useful way it is important to be sure of these assumptions in order that the formalisms are combined in ways which have, or which allow, the intended combined properties. Consequently we cannot necessarily expect to take on state-based formalism and one process-based formalism and combine them and get something sensible, especially since the act of combining can have subtle consequences. Here we concentrate on value-passing, how it is treated in each formalism, and how the formalisms can be combined so as to preserve certain properties. Specifically, the aim is to take from the many process-based formalisms definitions that will best fit with our chosen stat-based formalism, namely Z, so that the fit is simple, has no unintended consequences and is as elegant as possible

A symbolic semantics for a clculus for service-oriented computing

We introduce a symbolic characterisation of the operational semantics of COWS, a formal language for specifying and combining service-oriented applications, while modelling their dynamic behaviour. This alternative semantics avoids infinite representations of COWS terms due to the value-passing nature of communication in COWS and is more amenable for automatic manipulation by analytical tools, such as e.g. equivalence and model checkers. We illustrate our approach through a ‘translation service’ scenario

State- and event-based refinement

In this paper we give simple example abstract data types, with atomic operations, that are related by data refinement under a definition used widely in the literature, but these abstract data types are not related by singleton failure refinement. This contradicts results found in the literature. Further we show that a common way to change a model of atomic operations to one of value passing operations actually changes the underlying atomic operational semantics

Relational Rippling: a General Approach

We propose a new version of rippling, called relational rippling. Rippling is a heuristic for guiding proof search, especially in the step cases of inductive proofs. Relational rippling is designed for representations in which value passing is by shared existential variables, as opposed to function nesting. Thus relational rippling can be used to guide reasoning about logic programs or circuits represented as relations. We give an informal motivation and introduction to relational rippling. More details, including formal definitions and termination proofs can be found in the longer version of this paper, [Bundy and Lombart, 1995]

Observational mu calculus

We propose an extended modal mu-calculus to provide an `assembly language' for modal logics for real time, value-passing calculi, and other extended models of computation

Abstract games for infinite state processes

In this paper we propose finding winning strategies of abstract games as an approach to verification problems which permits both a variable level of abstraction and on-the-fly exploration. We describe a generic algorithm which, when instantiated with certain functions specific to the concrete game, computes a winning strategy. We apply this technique to bisimulation and model-checking of value-passing processes, and to timed automata

About compositional analysis of pi-calculus processes

We set up a logical framework for the compositional analysis of finite pi-calculus processes. In particular, we extend the partial model checking techniques developed for value passing process algebras to a nominal calculus, i.e. the pi-calculus. The logic considered is an adaptation of the ambient logic to the pi-calculus. As one of the possible applications, we show that our techniques may be used to study interesting security properties as confidentiality for (finite) pi-calculus processes