David H. Pitt

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This paper presents a survey of recent approaches in the application of the object-oriented paradigm to formal specification. The complexity of current information systems demands the use of a higher degree of formalism in the development process. Formal languages such as Z, VDM and Lotos have been used extensively in academic environments and research(More)
Pre-/postconditions have been extensively used in program specification, e.g. Z [Spi89], VDM [Jon86], and proof, e.g. Hoare logic, Dijkstra's guarded commands [DiF88]. In [ScP86, SPB90] the authors introduced neutral and central relations to formalise the concept of “the rest stays the same”. In this paper we abstract away from the specific definition of(More)
In this paper, we investigate the structure of the asynchronous behaviour of systems of cyclical, deterministic sequential processes. Specifically, we find conditions which, under certain finiteness assumptions, characterise periodic behaviours and pseudo-periodic behaviours, where a behaviour is periodic if it goes through a sequence of periods, i.e. of(More)
A local invariant is a set of states of a transition system with the property that every action possible from each of its states takes the system back into the local invariant, unless it is an ‘exit’ action, each of which is accessible from every state in the set via a sequence of non-‘exit’ actions. This idea supports a form of abstraction construction,(More)
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