In ZUM ’ 95 : The Z Formal Specification Notation
نویسندگان
چکیده
A report is given on work undertaken to produce a struc-tured speciication in Z of a model which aims to capture the essential abstractions of hypertext systems. The speciication is presented in part and the potential value of this speciication to the hypertext community is explored and discussed. We argue that this speciication provides a framework for hypertext systems in that it provides: explicit and un-ambiguous deenitions of hypertext terms, an explicit environment for the presentation, comparison and evaluation of hypertext systems and a foundation for future research and development in the eld. Although there are many formal reference models of hypertext, we have found Z expressive enough to allow a uniied account of a system and its operations. Our model does not restrict the speciier to any particular design, but provides a mathematical framework within which diierent models may be compared. Further, we were able to structure the speciication in order that the model could be described initially at the highest level of abstraction with complexity added at increasingly lower levels of abstraction. This structured speciication allows the functionality of hyper-text systems to be considered at diierent levels of granularity which, we argue, gives rise to a well-deened robust model and a beneecial environment within which to reason about hypertext design. The use of this model in presenting and comparing existing models, as well as its use in developing a new hypertext learning model, is brieey discussed.
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