Formally specifying reusable knowledge model components

Abstract

This paper outlines some of the problems with using predefined building blocks to specify knowledge level models of problem solving, in particular in the context of the KADS methodology. The definition of the basic building blocks in KADS, the primitive inferences, or knowledge sources, often seems to be inadequate to aid the knowledge engineer in constructing an abstract model of problem solving. We argue that the informal, verbal way in which the building blocks are defined is the cause of this problem, and propose to formalize them to make their semantics clear and to assess the consequences of various modeling decisions. We discuss choices among different formalizations, and show in detail the formalization of one class of knowledge sources.