Journal of Intelligent Information Systems - Special issue on methodologies for intelligent systems
On the decidability of query containment under constraints
PODS '98 Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Combining Horn rules and description logics in CARIN
Artificial Intelligence
A Portrait of the Semantic Web in Action
IEEE Intelligent Systems
Data Complexity of Query Answering in Expressive Description Logics via Tableaux
Journal of Automated Reasoning
Answering regular path queries in expressive description logics: an automata-theoretic approach
AAAI'07 Proceedings of the 22nd national conference on Artificial intelligence - Volume 1
Conjunctive query answering for the description logic SHIQ
IJCAI'07 Proceedings of the 20th international joint conference on Artifical intelligence
Data complexity of reasoning in very expressive description logics
IJCAI'05 Proceedings of the 19th international joint conference on Artificial intelligence
FDNC: decidable non-monotonic disjunctive logic programs with function symbols
LPAR'07 Proceedings of the 14th international conference on Logic for programming, artificial intelligence and reasoning
Conjunctive queries for a tractable fragment of OWL 1.1
ISWC'07/ASWC'07 Proceedings of the 6th international The semantic web and 2nd Asian conference on Asian semantic web conference
The Complexity of Conjunctive Query Answering in Expressive Description Logics
IJCAR '08 Proceedings of the 4th international joint conference on Automated Reasoning
Query Answering in the Description Logic Horn-$\mathcal{SHIQ}$
JELIA '08 Proceedings of the 11th European conference on Logics in Artificial Intelligence
LPAR '08 Proceedings of the 15th International Conference on Logic for Programming, Artificial Intelligence, and Reasoning
Query Answering in Description Logics: The Knots Approach
WoLLIC '09 Proceedings of the 16th International Workshop on Logic, Language, Information and Computation
Fusion of Logic Programming and Description Logics
ICLP '09 Proceedings of the 25th International Conference on Logic Programming
Query answering in description logics with transitive roles
IJCAI'09 Proceedings of the 21st international jont conference on Artifical intelligence
Conjunctive query answering in the description logic SH using knots
Journal of Computer and System Sciences
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Answering conjunctive queries (CQs) has been recognized as a key task for the usage of Description Logics (DLs) in a number of applications, and has thus been studied by many authors. In this paper, we present an algorithm for this problem in the DL ALCH which works in exponential time. It improves over previous algorithms which require double exponential time and is worst-case optimal, as already satisfiability testing in ALC is EXPTIME-complete. Furthermore, it shows that inverse roles cause an exponential jump in complexity; as recently shown, the problem is 2EXPTIME- complete for ALCI. The algorithm is based on a technique that compiles knowledge bases into sets of trees of depth 1. It is in coNP under data complexity (i.e., if the taxonomy part and the query are fixed), thus worst-case optimal. An extension from ALCH to DLs with further constructs is possible.