Imprecision and uncertainty in the UFO database model

Database systems which have a semantically rich underlying database model, can offer better, more user‐friendly facilities to model applications more efficiently and more truthfully. The object‐oriented database model (OODBM) is equipped with some important semantic constructs such as objects, classes, and the inheritance relationship; its emergence is one of the new steps towards semantically richer database models. Along the same path, the UFO (Uncertainty and Fuzziness in an Object‐oriented) database model enhances the OODBM with the ability to process and record fuzzy and uncertain (imprecise) information. This article discusses how imprecision and uncertainty are dealt with in the UFO database model. Such information is expressed by means of possibility distributions, and modeled by means of the proposed concept of “role objects.” The role objects model uncertain, tentative information about objects, and thus the uncertain roles that objects might play. Uncertain and imprecise data (found at the level of the attribute values, of the “is‐an‐instance‐of” relationship, and of the applicability of attributes and methods) as well as uncertain information (found at the level of the database scheme) are modeled using this new concept. © 1998 John Wiley & Sons, Inc.