We extend the description logic EL++ with reflexive roles
and range restrictions, and show that subsumption remains tractable if
a certain syntactic restriction is adopted. We also show that subsumption
becomes PSpace-hard (resp. undecidable) if this restriction is weakened
(resp. dropped). Additionally, we prove that tractability is lost when
symmetric roles are added: in this case, subsumption becomes ExpTime-
hard
What is the Semantic Web? Read on for a brief introduction to the Semantic Web, how to get started using it, and to understand why we should invest in making our content semantic.
Ontotext GraphDB is a highly-efficient and robust graph database with RDF and SPARQL support. This documentation is a comprehensive guide, which explains every feature of GraphDB as well as topics such as setting up a repository, loading and working with data, tuning its performance, scaling, etc.
I. Niles, and A. Pease. Proceedings of the International Conference on Formal Ontology in Information Systems - Volume 2001, page 2--9. New York, NY, USA, ACM, (2001)
K. Lüttich, T. Mossakowski, and B. Krieg-Brückner. Recent Trends in Algebraic Development Techniques, 17th International Workshop (WADT 2004), volume 3423 of Lecture Notes in Computer Science, page 106-125. Springer; Berlin; http://www.springer.de, (2005)
O. Kutz, J. Hastings, and T. Mossakowski. 15th International Conference on Artificial Intelligence: Methodology, Systems, Applications, volume 7557 of Lecture Notes in Computer Science, page 103-111. Springer, (2012)