Imprecision and uncertainty in the UFO database model

Abstract

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.

Fuzzy Techniques in Object Based Modeling

“…Recent efforts have extended these results to object oriented databases by introducing the related notions of classes, generalizations, specialization and inheritance [5,6,7,8]. The uncertainty is handled at data level and conceptual model level both [9,10,11].…”

“…CLASS NAME WITH m DEGREE where 0 m 1 [16,17] Like, for a class in a data model, we can write the syntax "Person WITH 0.8 DEGREE". The class will not be declared having degree 0 and 1.…”

STEP implementation of imperfect EXPRESS model in fuzzy object-oriented databases

“…In [3], the definition of graph-based operations to select and browse a FOODB that manages both crisp and fuzzy information was further proposed for the fuzzy graph-based model. A UFO (uncertainty and fuzziness in an object-oriented) database model was proposed in [21] to model fuzziness and uncertainty by means of fuzzy set theory and generalized fuzzy sets, respectively. The fact that the behavior and structure of the object are incompletely defined results in a gradual nature for the instantiation of an object.…”

Database design and querying within the fuzzy semantic model

“…Several proposals for extending object-oriented and semantic database models to support the management of fuzziness, uncertainty and imprecision of real-world at the class definition level have been recently proposed [12,9,13,25,22,15]. In this respect, the authors have proposed a new data model, namely the fuzzy semantic model (FSM) [6,7], that authorizes an entity to be, albeit partially, a member of its class according to a given degree of membership.…”