Design and Implementation of a Type System for a Knowledge Representation System

A knowledge representation system (krs) is made up of both a language to represent knowledge of a domain and well-deened reasoning facilities to infer new knowledge from known facts. This paper deals with krss close to frame-based systems, that include description logic systems and object-based systems. In these systems, the main relation that leads to inferences is subsumption. Knowledge terms are described through roles which refer to either other knowledge terms or data types. Subsumption between term descriptions is usually interpreted as data set inclusion, where data is either a knowledge term or an external term (integer, string, etc.). Although subsumption between knowledge terms is well-deened, its implementation on external data depends upon the host language since there are actually the data types of the krs. As a consequence, no krs is able to integrate a new data type (e.g. Matrix) such that its values can be safely involved in subsumption and further inferences. This is the problem addressed in this paper. The proposed solution is the design of a polymorphic type system connected to both the krs and the host language. It is designed so that it can extend the krs with any data type implementation available in the host language (library, user-coded). Meanwhile, the values of the new data type get safely involved in the krs reasoning processes. The presented type system avoids the incompleteness of subsumption due to its incomplete processing on external data. Conception et R ealisation d'un Syst eme de Types pour un Syst eme de Repr esentation des Connaissances R esum e : Un syst eme de repr esentation des connaissances (src) est constitu e, d'une part d'un lan-gage pour repr esenter et structurer les connaissances d'un domaine, et, d'autre part, de processus de raisonnement bien d eenis pour l'inf erence de nouvelles connaissances a partir de celles d ejj a repr esen-t ees. Ce rapport traite des srcs issus des syst emes de frames, tels que les syst emes de descriptions logiques ou les syst emes a base d'objets. La relation principale qui m ene a des inf erences y est la subsomption. Les termes de connaissances sont d ecrits par le biais d'attributs qui font r ef erence, ou bien a d'autres termes de connaissances, ou bien a des types de donn ees externes. La subsomption entre descriptions de termes est souvent interpr et ee comme l'inclusion ensembliste, o u les ensembles …