Set operations in semantic data models

Class creation by set operations has largely been ignored in the literature. Precise semantics of set operations on complex objects require a clear distinction between the dual notions of a set and a type, both of which are present in a class. Our paper fills this gap by presenting a framework for executing set-theoretic operations on the class construct. The proposed set operations determine both the type description of the derived class as well as its set membership. For the former, we develop inheritance rules for property characteristics such as single- versus multi-valued and required versus optional. For the later, we borrow the object identity concept from data modeling research. Our framework allows for property inheritance among classes that are not necessarily is-a related

A Flexible Approach to the Multidimensional Model: The Fuzzy Datacube

As a result of the use of OLAP technology in new fields of knowledge and the merge of data from different sources, it has become necessary for models to support this technology. In this paper, we propose a new multidimensional model that can manage imprecision both in dimensions and facts. Consequently, the multidimensional structure is able to model data imprecision resulting from the integration of data from different sources or even information from experts, which it does by means of fuzzy logic