Abstract

In contrast to the relatively complex information that can be expressed in DL ABoxes (which we might call knowledge or information), databases and other sources such as files, semistructured data, and the World Wide Web provide rather simpler data, which must however be managed effectively. This chapter surveys the major classes of application of Description Logics and their reasoning facilities to the issues of data management, including: (i) expressing the conceptual domain model/ontology of the data source, (ii) integrating multiple data sources, and (iii) expressing and evaluating queries. In each case we utilize the standard properties of Description Logics, such as the ability to express ontologies at a level closer to that of human conceptualization (e.g., representing conceptual schemas), determining consistency of descriptions (e.g., determining if a query or the integration of some schemas is consistent), and automatically classifying descriptions that are definitions (e.g., queries are really definitions, so we can classify them and determine subsumption between them).

Introduction

According to [EIMasri and Navathe, 1994], a database is a coherent collection of related data, which have some “inherent meaning”. Databases are similar to knowledge bases because they are usually used to maintain models of some universe of discourse (UofD). Of course, the purpose of such computer models is to support end-users in finding out things about the world, and therefore it is important to maintain an up-to-date and error-free model.