A description-logic based knowledge representation system is more than an inference engine for a particular description logic. A knowledge representation system must provide a number of services to human users, including presentation of the information stored in the system in a manner palatable to users and justification of the inferences performed by the system. If human users cannot understand what the system is doing, then the development of knowledge bases is made much more difficult or even impossible. A knowledge representation system must also provide a number of services to application programs, including access to the basic information stored in the system but also including access to the machinations of the system. If programs cannot easily access and manipulate the information stored in the system, then the development of applications is made much more difficult or even impossible.
Deborah L. McGuinness, Peter F. Patel-Schneider