ACM Transactions on Database Systems (TODS)
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
Data integration: a theoretical perspective
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
A Conjunctive Query Language for Description Logic Aboxes
Proceedings of the Seventeenth National Conference on Artificial Intelligence and Twelfth Conference on Innovative Applications of Artificial Intelligence
Description logics for databases
The description logic handbook
Discrete Applied Mathematics - Special issue: Discrete algorithms and optimization, in honor of professor Toshihide Ibaraki at his retirement from Kyoto University
Reasoning in Description Logics by a Reduction to Disjunctive Datalog
Journal of Automated Reasoning
Building Scalable Semantic Peer-to-Peer Data Management Systems: The SomeWhere Approach
ENC '07 Proceedings of the Eighth Mexican International Conference on Current Trends in Computer Science
Conjunctive query containment and answering under description logic constraints
ACM Transactions on Computational Logic (TOCL)
SFCS '79 Proceedings of the 20th Annual Symposium on Foundations of Computer Science
Data Complexity of Query Answering in Expressive Description Logics via Tableaux
Journal of Automated Reasoning
Computational aspects of monotone dualization: A brief survey
Discrete Applied Mathematics
Query Answering in the Description Logic Horn-$\mathcal{SHIQ}$
JELIA '08 Proceedings of the 11th European conference on Logics in Artificial Intelligence
Temporal Description Logics: A Survey
TIME '08 Proceedings of the 2008 15th International Symposium on Temporal Representation and Reasoning
Web Semantics: Science, Services and Agents on the World Wide Web
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
Characterizing data complexity for conjunctive query answering in expressive description logics
AAAI'06 Proceedings of the 21st national conference on Artificial intelligence - Volume 1
Integrating description logics and action formalisms: first results
AAAI'05 Proceedings of the 20th national conference on Artificial intelligence - Volume 2
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
Worst-case optimal conjunctive query answering for an expressive description logic without inverses
AAAI'08 Proceedings of the 23rd national conference on Artificial intelligence - Volume 1
Terminological reasoning in SHIQ with ordered binary decision diagrams
AAAI'08 Proceedings of the 23rd 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
A correspondence theory for terminological logics: preliminary report
IJCAI'91 Proceedings of the 12th international joint conference on Artificial intelligence - Volume 1
Reasoning on UML class diagrams
Artificial Intelligence
FDNC: Decidable nonmonotonic disjunctive logic programs with function symbols
ACM Transactions on Computational Logic (TOCL)
Regular path queries in expressive description logics with nominals
IJCAI'09 Proceedings of the 21st international jont conference on Artifical intelligence
Query answering in description logics with transitive roles
IJCAI'09 Proceedings of the 21st international jont conference on Artifical intelligence
The complexity of finite model reasoning in description logics
Information and Computation - Special issue: 19th international conference on automated deduction (CADE-19)
Complexity of planning in action formalisms based on description logics
LPAR'07 Proceedings of the 14th international conference on Logic for programming, artificial intelligence and reasoning
Reasoning over extended ER models
ER'07 Proceedings of the 26th international conference on Conceptual modeling
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
Journal on data semantics X
LPAR'10 Proceedings of the 17th international conference on Logic for programming, artificial intelligence, and reasoning
Reasoning about actions using description logics with general TBoxes
JELIA'06 Proceedings of the 10th European conference on Logics in Artificial Intelligence
Ontology-based data access with databases: a short course
RW'13 Proceedings of the 9th international conference on Reasoning Web: semantic technologies for intelligent data access
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Answering conjunctive queries (CQs) has been recognized as an important task for the widening use of Description Logics (DLs) in a number of applications. The problem has been studied by many authors, who developed a number of different techniques for its solution. We present a novel approach to CQ answering that is based on knots, which are schematic trees of depth at most one that can be used to represent the terminological information represented in a TBox. They allow us to obtain an algorithm for the DL SH that has some advantages with respect to previous approaches, proceeding as follows. We build a compilation of an input knowledge base using knots, and then use this compilation to answer CQs in two stages. In the first stage we employ knots to rewrite the input query into a set of queries (a union of CQs, short UCQ) that incorporate the terminological constraints. In the next stage we answer the query over the full knowledge base, by answering the constructed UCQ over a set of relational structures that are obtained by enriching the assertional part of the knowledge base. Since in the first stage we process the query and the taxonomy, and the assertional part of the knowledge base is only processed in the second stage, parts of the computation can be reused; in particular, answering a query over changing assertional data amounts to re-executing the last step. Notably, the algorithm handles CQs with distinguished (i.e., output) variables in a direct manner and scales down nicely: while double exponential in general, it runs in single exponential time under various restrictions on transitive roles in queries, including the case of CQ answering in the DL ALCH. This is worst-case optimal, given that CQ answering is 2ExpTime-complete for SH and ExpTime-complete already for the core expressive DL ALC. Furthermore, the last step is amenable to a realization in disjunctive Datalog, which yields a worst-case optimal implementation under data complexity.