In Description Logics (DLs) and in the ontology-based data access (OBDA) scenario, the use of actual datatypes (such as those adopted in DBMSs) has received only limited attention, although datatypes, with their predefined semantics, might have a substantial impact on the computational complexity of inference in ontology systems. In this work we aim at overcoming these limitations, and study the impact of adding datatypes to the OBDA scenario. To this aim, we introduce a language for datatypes and we define the notion of a datatype hierarchy, constituted by a set of datatypes that depend on each other. We classify hierarchies in three classes according to their distinguishing properties, and we establish a theoretical framework for datatypes in the OBDA scenario, based on three major components: a DL, a class of datatype hierarchies, and a query language. We establish the computational complexity of query answering for various significant instantiations of this framework, as ranging from FOL-rewritable to coNP in data complexity.
IOS Press, Inc.
6751 Tepper Drive
Clifton, VA 20124
Tel.: +1 703 830 6300
Fax: +1 703 830 2300 email@example.com
(Corporate matters and books only) IOS Press c/o Accucoms US, Inc.
For North America Sales and Customer Service
West Point Commons
Lansdale PA 19446
Tel.: +1 866 855 8967
Fax: +1 215 660 5042 firstname.lastname@example.org