this paper have been presented at the 4th European Summer School in Logic, Language and Information, University of Essex, 1992; at the Tempus Summer School for Algebraic and Categorical Methods in Computer Science, Masaryk University, Brno, 1993; and the Summer School in Logic Methods in Concurrency, Aarhus University, 1993. I would like to thank the organisers and the participants of these summer schools, and of the Banff higher order workshop. I would also like to thank Julian Bradfield for use of his Tex tree constructor for building derivation trees and Carron Kirkwood, Faron Moller, Perdita Stevens and David Walker for comments on earlier drafts.

We introduce a temporal logic for the polyadic ß-calculus based on fixed point extensions of Hennessy-Milner logic. Features are added to account for parametrisation, generation, and passing of names, including the use, following Milner, of dependent sum and product to account for (unlocalised) input and output, and explicit parametrisation on names using lambda-abstraction and application. The latter provides a single name binding mechanism supporting all parametrisation needed. A proof system and decision procedure is developed based on Stirling and Walker's approach to model checking the modal ¯-calculus using constants. One difficulty, for both conceptual and efficiency-based reasons, is to avoid the explicit use of the !-rule for parametrised processes. A key idea, following Hennessy and Lin's approach to deciding bisimulation for certain types of value-passing processes, is the relativisation of correctness assertions to conditions on names. Based on this idea a proof system and ...

We present a proof system for determining satisfaction between processes in a fairly general process algebra and assertions of the modal µ-calculus. The proof system is compositional in the structure of processes. It extends earlier work on compositional reasoning within the modal µ-calculus and combines it with techniques from work on local model checking. The proof system is sound for all processes and complete for a class of finite-state processes.

Abstract. This paper presents a method for the decomposition of HML formulae. It can be used to decide whether a process algebra term satisfies a HML formula, by checking whether subterms satisfy certain formulae, obtained by decomposing the original formula. The method uses the structural operational semantics of the process algebra. The main contribution of this paper is that an earlier decomposition method from Larsen [14] for the De Simone format is extended to the more general ntyft/ntyxt format without lookahead. 1

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Recently the use of formal methods in describing and analysing the behaviour of (computer) systems has become more common. This has resulted in the proliferation of a wide variety of different specification formalisms, together with analytical techniques and methodologies for specification development. The particular specification formalism adopted for this study is LOTOS, an ISO standard formal description technique. Although there are many works dealing with how to write LOTOS specifications and how to develop a LOTOS specification from the initial abstract requirements specification to concrete implementation, relatively few works are concerned with the problems of expressing and proving the correctness of LOTOS specifications, i.e. verification. The main objective of this thesis is to address this shortfall by investigating the meaning of verification as it relates to concurrent systems in general, and in particular to those systems described using LOTOS. Further goals are to autom...

Model checking is an automatic technique for verifying nite state systems: in this approach, properties are expressed in a temporal logic and systems are modelled as transition systems. A main problem of model checking is state explosion: very complex systems are often represented by transition systems with a prohibitive number of states. The primary cause of this problem is the parallel composition of interacting processes. Many techniques have been proposed to attack this problem, among them compositional techniques. These techniques reduce state explosion exploiting the natural decomposition of complex systems into processes. In this paper we present a formula-based compositional rule that allows us to deduce a property of a parallel composition of processes by checking it only on a component process. Keywords: model checking, compositionality, temporal logic, state explosion. 1.

s from the Third Workshop Flemming Nielson (editor) October 1993 1 Introduction The third DART workshop took place on Thursday August l9th and Friday August 20th at the Department of Computer Science (DIKU) at the University of Copenhagen; it was organized by Mads Rosendahl and others at DIKU, and Torben Amtoft and Susanne Brønberg helped producing this report. The first day comprised survey presentations whereas the second contained more research oriented talks. The primary aim of the workshop was to increase the awareness of DART participants for each other's work, to stimulate collaboration between the di#erent groups, and to inform Danish industry about the skills possessed by the groups. The DART project started in March 1991 (prematurely terminating a smaller project on Formal Implementation, Transformation and Analysis of Programs) and is funded by the Danish Research Councils as part of the Danish Research Programme on Informatics. To date it has received about 8 million Danis...

In this paper we study the problem of verifying general temporal and functional properties of mobile and dynamic process networks, cast in terms of the pi-calculus. Much of the expressive power of this calculus derives from the combination of name generation and communication (to handle mobility) with dynamic process creation. In the paper we introduce the ß-¯-calculus, an extension of the modal mu-calculus with name equality, inequality, first-order universal and existential quantification, and primitives for name input and output as an appropriate temporal logic for the picalculus. A compositional proof system is given with the scope of verifying dynamic networks of pi-calculus agents against properties specified in this logic. The proof system is shown to be sound in general and complete for the modal fragment of the specification logic. Milner's encoding of data types into the pi-calculus provide an interesting application study, since the encodings make essential use of all the d...

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