How firing conditions help inheritance

Strulo, Ben

doi:10.1007/3-540-60271-2_125

Cited by 25 publications

(12 citation statements)

References 5 publications

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“…This illustrates an interesting aspect of specifying internal operations in Z -they can output data (in fact some interpretations of unobservableness in Z outlaw this possibility e.g. CR92], but generally this is the case Str95,WJ94]). This is in contrast to a process algebra where typically internal actions can have no data attributes.…”

Section: Internal Operations With Outputmentioning

confidence: 99%

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Specifying and Refining Internal Operations in Z

et al. 1998

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Abstract. An important aspect in the speci cation of distributed systems is the role of the internal (or unobservable) operation. Such operations are not part of the interface to the environment (i.e. the user cannot invoke them), however, they are essential to our understanding and correct modelling of the system. In this paper we are interested in the use of the formal speci cation notation Z for the description of distributed systems. Various conventions have been employed to model internal operations when specifying such systems in Z. If internal operations are distinguished in the speci cation notation, then re nement needs to deal with internal operations in appropriate ways. Using an example of a telecommunications protocol we show that standard Z re nement is inappropriate for re ning a system when internal operations are speci ed explicitly. We present a generalization of Z re nement, called weak renement, which treats internal operations di erently from observable operations when re ning a system. We discuss the role of internal operations in a Z speci cation, and in particular whether an equivalent speci cation not containing internal operations can be found. The nature of divergence through livelock is also discussed.

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Section: Internal Operations With Outputmentioning

confidence: 99%

“…Other work in this area includes Str95], But97] and Eva97]. The work of Strulo,Str95], was discussed in Section 3.4, and we consider here the proposals of Butler But97] and Evans Eva97].…”

Section: Related Workmentioning

confidence: 99%

Specifying and Refining Internal Operations in Z

et al. 1998

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“…They can arise either due to the natural non-determinism of a distributed system 11], or due to communication within the system 15] or due to some aspect of the system being hidden at this level of abstraction 2]. The necessity for the speci cation of internal events in process algebras is well recognised 15], and a number of researchers have found it convenient or necessary to specify internal operations in Z when specifying distributed systems 7,16,19,21,9]. In each case the internal operation is speci ed as normal and either has a distinguished name or informal commentary telling us that it is not part of the user interface.…”

Section: Internal Operationsmentioning

confidence: 99%

“…Now the use of Z for the speci cation of sequential systems is gaining acceptance, attention is being turned to new domains of applicability -one such example is the use of Z for the speci cation of concurrent and distributed systems 5,17,14,13,19]. One aspect that is important in the speci cation of distributed systems is the role of the internal (or unobservable) operation.…”

Section: Introductionmentioning

confidence: 99%

Weak refinement in Z

Derrick

Boiten

Bowman

et al. 1997

Lecture Notes in Computer Science

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Abstract. An important aspect in the speci cation of distributed systems is the role of the internal (or unobservable) operation. Such operations are not part of the user interface (i.e. the user cannot invoke them), however, they are essential to our understanding and correct modelling of the system. Various conventions have been employed to model internal operations when specifying distributed systems in Z. If internal operations are distinguished in the speci cation notation, then re nement needs to deal with internal operations in appropriate ways. However, in the presence of internal operations, standard Z re nement leads to undesirable implementations. In this paper we present a generalization of Z re nement, called weak re nement, which treats internal operations di erently from observable operations when re ning a system. We illustrate some of the properties of weak re nement through a speci cation of a telecommunications protocol.

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“…This is an alternative proof theoretic characterisation of refinement, which is closely connected to refinement in the behavioural approach, as discussed, for example, in [3] and [16].…”

Section: Sp-refinementmentioning

confidence: 98%