Sound and Complete Forward and backward Chainingd of Graph Rules
ICCS '96 Proceedings of the 4th International Conference on Conceptual Structures: Knowledge Representation as Interlingua
The Description Logic Handbook
The Description Logic Handbook
Tractable Reasoning and Efficient Query Answering in Description Logics: The DL-Lite Family
Journal of Automated Reasoning
Terminological cycles in a description logic with existential restrictions
IJCAI'03 Proceedings of the 18th international joint conference on Artificial intelligence
Extending decidable cases for rules with existential variables
IJCAI'09 Proceedings of the 21st international jont conference on Artifical intelligence
Efficient Query Answering for OWL 2
ISWC '09 Proceedings of the 8th International Semantic Web Conference
On rules with existential variables: Walking the decidability line
Artificial Intelligence
Ontological queries: Rewriting and optimization
ICDE '11 Proceedings of the 2011 IEEE 27th International Conference on Data Engineering
Optimized query rewriting for OWL 2 QL
CADE'11 Proceedings of the 23rd international conference on Automated deduction
A general Datalog-based framework for tractable query answering over ontologies
Web Semantics: Science, Services and Agents on the World Wide Web
The combined approach to ontology-based data access
IJCAI'11 Proceedings of the Twenty-Second international joint conference on Artificial Intelligence - Volume Volume Three
A sound and complete backward chaining algorithm for existential rules
RR'12 Proceedings of the 6th international conference on Web Reasoning and Rule Systems
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Querying large databases while taking ontologies into account is currently a very active domain research. In this paper, we consider ontologies described by existential rules (also known as Datalog+/-), a framework that generalizes lightweight description logics. A common approach is to rewrite a conjunctive query w.r.t an ontology into a union of conjunctive queries (UCQ) which can be directly evaluated against a database. However, the practicability of this approach is questionable due to 1) the weak expressivity of classes for which efficient rewriters have been implemented 2) the large size of optimal rewritings using UCQ. We propose to use semi-conjunctive queries (SCQ), which are a restricted form of positive existential formulas, and compute sound and complete rewritings, which are union of SCQ (USCQ). A novel algorithm for query rewriting, COMPACT, is presented. It computes sound and complete rewritings for large classes of ontologies. First experiments show that USCQ are both efficiently computable and more efficiently evaluable than their equivalent UCQ.