In the field of Knowledge Engineering, dissatisfaction with the rapid-prototyping approach has led to a number of more principled methodologies for the construction of knowledgebased systems. Instead of immediately implementing the gathered and interpreted knowledge in a given implementation formalism according to the rapid-prototyping approach, many such methodologies centre around the notion of a conceptual model: an abstract, implementation independent description of the relevant problem solving expertise. A conceptual model should describe the task which is solved by the system and the knowledge which is required by it. Although such conceptual models have often been formulated in an informal way, recent years have seen the advent of formal and operational languages to describe such conceptual models more precisely, and operationally as a means for model evaluation. In this paper, we study a number of such formal and operational languages for specifying conceptual mode...

Much of the work on validation and verification of knowledge based systems (KBSs) has been done in terms of implementation languages (mostly rule-based languages). Recent papers have argued that it is advantageous to do validation and verification in terms of a more abstract and formal specification of the system. However, constructing such formal specifications is a difficult task. This paper proposes the use of formal specification languages for KBS-development that are closely based on the structure of informal knowledge-models. The use of such formal languages has as advantages that (i) we can give strong support for the construction of a formal specification, namely on the basis of the informal description of the system; and (ii) we can use the structural correspondence to verify that the formal specification does indeed capture the informally stated requirements. This paper has been submitted to the Journal of Human Computer Studies (formerly the Journal of Man Machine Studies)....

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Conceptual models, such as the ones used in KADS, have been proposed as important tools for developing knowledge-based systems. These models come usually associated with a domain-independent task such as planning or diagnosis. Such strategy, however, has been criticized for not paying enough attention to the representation and acquisition of domain knowledge. It has been argued that ontologies can provide this missing step. Ontologies are coherent specifications (theories) of the main concepts involved in application domains such as physical systems, medicine or law. Nevertheless, research on these two perspectives have been usually separated. One can find libraries of ontologies (such as the ones developed with ONTOLINGUA) or conceptual models (such as the KADS library), but rarely both. In this article, we show with a specific example that the two ends meet. We propose separately a KADS conceptual model for a central legal task (namely assessment) and an ontology of lega...