Abstract:
In a unified conceptual model for first-order knowledge bases the data and
knowledge are modelled formally in a uniform way. A knowledge base is
maintained by modifying its conceptual model and by using those
modifications to specify changes to its implementation. The maintenance
problem is to determine which parts of that model should be checked for
correctness. in response a change in the application. The maintenance
problem is not computable for first-order knowledge bases. Two things in
the conceptual model are joined by a maintenance link if a modification to
one of them means that the other must be checked for correctness, and so
possibly modified, if consistency of the model is to be preserved. A
characterisation is given of four different kinds of maintenance links in a
unified conceptual model. Two of these four kinds of maintenance links
can be removed by transforming the conceptual model.
