Controlling information flows through a system is the fundamental issue in information security. It turns out that making precise the notion of information flow, and in particular the absence of information flow, is a remarkably subtle question. Many formalizations have been proposed, many inspired by the seminal ideas of Goguen and Meseguer with their notion of non-interference. Even now the s...

The formalism of modal transition systems (MTS) is a well established framework for systems specification as well as abstract interpretation. Nevertheless, due to incapability to capture some useful features, various extensions have been studied, such as e.g. mixed transition systems or disjunctive MTS. Thus a need to compare them has emerged. Therefore, we introduce transition system with obli...

The real world exhibits concurrency at all levels of scale – from atomic, through human, to astronomic. This concurrency is endemic. Central points of control do not remain stable for long. Most of the novel paradigms identified in the GC7 description paper hint at something stronger – namely that central points of control actively work against the logic and efficiency of whatever it is that is...

In process algebras like μCRL and ACP communication is defined globally. In the context of component-based architectures one wishes to define subcomponents of a system separately, including communication within that subcomponent. We define a process algebra with an operator for local communication that facilitates component-based architectures. Besides being compositional, this language is aime...

We propose a process algebra obtained by extending a combination of the process algebra with continuous relative timing from Baeten and Middelburg [Process Algebra with Timing, Springer, Chap. 4, 2002] and the process algebra with propositional signals from Baeten and Bergstra [Theoretical Computer Science 177:381–405, 1997]. The proposed process algebra makes it possible to deal with the behav...

The possibility of two or more actions to be performed consecutively at the same point in time is not excluded in the process algebras from the framework of process algebras with timing presented by Baeten and Middelburg [Handbook of Process Algebra, Elsevier, 2001, Chapter 10]. This possibility is useful in practice when describing and analyzing systems in which actions occur that are entirely...

This note contains the contribution to the Concurrency Column of the EATCS Bulletin of February, 2004. It indicates on the one hand what the strengths of process algebras are, and on the other hand mentions a major shortcoming. Using elementary process algebra it is hard to prove correctness of complex distributed algorithms, protocols and systems. We encountered this when providing a process a...

The-angelic choice is an operator that captures the behaviour of the external choice of CSP in a branching time setting. The idea of the-angelic choice is to delay any choice until an observable action happens. In this way, this new operator avoids preemption introduced by internal actions (actions). It is studied in theories with abstraction, more precisely, branching bisimulation and-bisimula...

An extension of Milner's CCS is presented. The language takes into account a number of resources/processors which have processes at disposal. It enables to consider various distributions and nesting of (sub)processes. Both an operational semantics in Plotkin style and bisimulation semantics for the language are deened. An axiomatiza-tion for nite processes is given, that may be the basis for an...

A Master Equation provides a complete probabilistic description of the dynamics of stochastic processes. We give a master equation for a small stochastic process algebra (a subset of CCS with interaction rates). We show that it is equivalent to the standard Chemical Master Equation, connecting our process algebra to the stochastic chemistry of unary and binary reactions.