The knowledge-systems community is interested in easing the knowledge-system development process. One approach, the mechanisms approach, views knowledge systems as a set of tasks, each of which can be realized by a computation mechanism. To be effective, knowledge-acquisition (KA) tools must be automatically configured once a set of mechanisms has been selected. We present a method for automatically generating a model-based KA tool for a given set of mechanisms. The method advocates combining KA mechanisms, which acquire knowledge in the small, and a set of strategies that provide a global view of the KA activity. We show that these global strategies are necessary for the KA tool to efficiently interact with a domain expert.
To support the sharing and reuse of formally represented knowledge among AI systems, it is useful to define the common vocabulary in which shared knowledge is represented. A specification of a representational vocabulary for a shared domain of discourse—definitions of classes, relations, functions, and other objects—is called an ontology. This paper describes a mechanism for defining ontologies that are portable over representation systems. Definitions written in a standard format for predicate calculus are translated by a system called Ontolingua into specialized representations, including frame-based systems as well as relational languages. This allows researchers to share and reuse ontologies, while retaining the computational benefits of specialized implementations.
We discuss how the translation approach to portability addresses several technical problems. One problem is how to accommodate the stylistic and organizational differences among representations while preserving declarative content. Another is how to translate from a very expressive language into restricted languages, remaining system-independent while preserving the computational efficiency of implemented systems. We describe how these problems are addressed by basing Ontolingua itself on an ontology of domain-independent, representational idioms.
We argue that it is important for the development of large knowledge models to integrate conceptual and operational modeling. We show that conceptual models can be operationalized by continuous refinement, without the need for a separate manual and structure-transforming implementation phase. Moreover, we show that such a continuity can be the basis for a fruitful integration of both kinds of modeling in a spiral development cycle. This allows us to integrate the best of both worlds: (1) the sloppiness required by conceptual modeling in order to develop structures unhampered by the constraints of an operational language; and (2) the feedback that an operational language provides for the ongoing model development process by allowing for testing, validating, and analysing the formalized structures of the model. To support our claims, we show how a large conceptual model of cancer-chemotherapy administration benefits from this integrating view on modeling.