A Terminological Logic with Defaults: A Definition and an Application

Abstract

In this paper we present a terminological language whi ch includes defaults , and a definition of default subsumption based on the notion of skeptical inherita nce in default reasoning . Except for the inclusion of defaults the language is limited when compared to most terminological logics. Howev er defaults are a ne cessa ry construct in many applications and we suggest that the language presented here is a useful tradeoff between different. types of expressivity. We present an algorithm for classifying n ew concepts into the default. hierarchy representing the taxonomy, and in addition an algorithm for what we call default classification, suitable for interactive reasoning about. individuals. We describe a diagnosis application whi ch has been implemented using this langu age and reasoning me chanisms. We present an evaluation of the diagnosis application on the basis of comparison with 63 patient protocols. We co nclude that. the language pr esented is in fa ct adequate for the application pr esented here and hypoth es ize that. it is interesting for a significant gro up of applications.