Abstract:
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. In a unified
conceptual model for first-order knowledge bases the data
and knowledge are modelled formally in a uniform way, 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. In this way the
maintenance problem is simplified.
