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This paper describes a structuring scheme for the VDM Specification Language. A VDM document may be split into a number of modules which may be parameterised. Modules may import and export constructs. A parameterised module may be instantiated by another module. We define an abstract syntax and give a compositional denotational semantics. Context Conditions are discussed informally, but are not set...
Stepwise refinement can be formalised in a natural way by regarding specifications as unimplemented program components. We present a graphical notation for specifications and their refinement rules which supports this approach. The resulting development style is proposed as an appropriate model for introductory programming instruction.
Clear indications are awaited from within the standards bodies before the most appropriate direction will emerge for the continuation of this work—i.e. whether it should be purely concerned with the GKS Review or with developing new graphics standards, possibly including a radically different successor to GKS, within the context of a Computer Graphics Reference Model. Either way (or both), there is...
The FOREST project, supported under the Alvey initiative, addressed the problem of capture and specification of requirements of software systems. The specification technique is based on the use of a formal system built around a form of modal logic, which has come to be referred to as MAL, which permits both the effects of actions and the circumstances in which they are to be invoked to be defined...
VDM development with Ada as the target language is examined. The aim is to study in detail the issues involved and to demonstrate the feasibility of providing semi-automatic tool support for VDM/Ada development, this support being based on a "rule set" for the process. Familiarity with VDM and Ada is assumed.
It proves very useful to give a formal specification of the software to be developed before the development. To write formal specifications, a specification language is to be used. This paper describes the specification language NUSL which has a supporting system. NUSL is an applicative executable specification language, centered around the concept of data abstraction, with module construct...
In Flagship, we have attempted to perform a very gradual introduction of the use of formal methods without proclaiming it to be the answer to all of our problems. Since this is not a formal methods project, our primary concern has been to gain some benefit from the use of formal methods, rather than to research their use in an industrial environment. In particular, this led us to drive our...
A three year research project is currently being undertaken at Leicester University, The National Physical Laboratory (NPL) and The British Standards Institution (BSI). The project aims to produce a formal definition of the syntax and semantics of the programming language Modula-2, written in VDM Meta IV, together with a rigorously verified interpreter derived directly from the definition. In the...
This paper describes the design validation process adopted by the VLSI Distributed Array Processor (VDAP) Project. In this project structured, informal design techniques were used in the hardware design process, but the validation team used some of the tools and methods of VDM as a means of defining the testing strategy.
VVSL is a VDM specification language of the ‘British School’ with modularisation constructs allowing sharing of hidden state variables and parameterisation constructs for structuring specifications, and with constructs for expressing temporal aspects of the concurrent execution of operations which interfere via state variables. VVSL was designed and is being used in the ESPRIT project 1283: VIP. ...
Different calculi of partial or three-valued predicates have been used and studied by several authors in the context of software specification, development and validation. This paper offers a critical survey on the development of three-valued logics based on such calculi. In the first part of the paper we review two three-valued predicate calculi, based on, respectively, McCarthy's and Kleene's...
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