Foundations of Semantic Web Technologies
Foundations of Semantic Web Technologies
LUBM: A benchmark for OWL knowledge base systems
Web Semantics: Science, Services and Agents on the World Wide Web
SPARQL beyond subgraph matching
ISWC'10 Proceedings of the 9th international semantic web conference on The semantic web - Volume Part I
Querying semantic web data with SPARQL
Proceedings of the thirtieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Optimizing query answering over OWL ontologies
ESWC'11 Proceedings of the 8th extended semantic web conference on The semanic web: research and applications - Volume Part II
Semantic query answering in digital libraries
SETN'12 Proceedings of the 7th Hellenic conference on Artificial Intelligence: theories and applications
Magic-Sets for datalog with existential quantifiers
Datalog 2.0'12 Proceedings of the Second international conference on Datalog in Academia and Industry
Cost based query ordering over OWL ontologies
ISWC'12 Proceedings of the 11th international conference on The Semantic Web - Volume Part I
Querying Semantic Data on the Web?
ACM SIGMOD Record
Disjunctive datalog with existential quantifiers: Semantics, decidability, and complexity issues
Theory and Practice of Logic Programming
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The SPARQL query language is currently being extended by W3C with so-called entailment regimes, which define how queries are evaluated under more expressive semantics than SPARQL's standard simple entailment. We describe a sound and complete algorithm for the OWL Direct Semantics entailment regime. The queries of the regime are very expressive since variables can occur within complex class expressions and can also bind to class or property names.We propose several novel optimizations such as strategies for determining a good query execution order, query rewriting techniques, and show how specialized OWL reasoning tasks and the class and property hierarchy can be used to reduce the query execution time. We provide a prototypical implementation and evaluate the efficiency of the proposed optimizations. For standard conjunctive queries our system performs comparably to already deployed systems. For complex queries an improvement of up to three orders of magnitude can be observed.