Knowledge Representation and Semantics in a Complex Domain: The UNIX Natural Language Help System GOETHE

It is commonly agreed ihat natural language systems fox" semantically rich domains require a level of sema~tic representation in order to provide for a sufficiently deep processing of the natural language input. The level of semantic representation is sometimes called a representation of linguistic knowledge. In addition, a natural language help system also requires a lo~owledge base of the application domain in order to answer the requests for domain specific help. The level of knowledge representation is sometimes called a representation of world knowledge. Most present day natural language processing sy,'stems, including, amongst others, SRI's Core I_,anguage Engine (Alshawi et.al. 1986), ESPRIT I project ACORD (Bez et.al. 1990), and the UNIX natural language help systems UNIX-Consultant (Wilensky et.al. 1988), SINIX-Consultant (Wahlster et.al. 1988), and AQUA (Ouilici et.al. 1986), keep the two levels of representation distinct. In addition, there usually is no feed-back of information between the semantic representation and the knowledge base. Thus, parsing is supposed to result in a complete semantic representation of the user input which then is passed on to tilt knowledge base manager for further processing. This kind of architecture follows a strategy, that can be called stepwise processing. We claim that for complex domains this kind of approach is inadequate because it ig,mrcs the user's cognitive misconceptions about the particular application. Instead, we wish to argue that at least with respect to semantics and knowledge representation in natural language help systems an h~tegmted approach should be preferred, in the approach we advocate, semantics and knowledge representation interact to correct (or complete) a possibly incorrect (or incomplete) semantic representation. The mechanism by which this is achieved is based on the notion of a fi'ame-semandcs (cf. Heyer et.al. 1988, tlausser 1989). We demonstrate our "integrated approach with examples from GOETHE, a natural language help system for UNIX as a complex domain.