Open AccessProceedings Article
On the complexity of consistent query answering in the presence of simple ontologies
Meghyn Bienvenu
- pp 705-711
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TLDR
In order to be able to handle arbitrary conjunctive queries, a novel inconsistency-tolerant semantics is proposed and it is shown that under this semantics, first-order expressibility is always guaranteed.Abstract:
Consistent query answering is a standard approach for producing meaningful query answers when data is inconsistent. Recent work on consistent query answering in the presence of ontologies has shown this problem to be intractable in data complexity even for ontologies expressed in lightweight description logics. In order to better understand the source of this intractability, we investigate the complexity of consistent query answering for simple ontologies consisting only of class subsumption and class disjointness axioms. We show that for conjunctive queries with at most one quantified variable, the problem is first-order expressible; for queries with at most two quantified variables, the problem has polynomial data complexity but may not be first-order expressible; and for three quantified variables, the problem may become co-NP-hard in data complexity. For queries having at most two quantified variables, we further identify a necessary and sufficient condition for first-order expressibility. In order to be able to handle arbitrary conjunctive queries, we propose a novel inconsistency-tolerant semantics and show that under this semantics, first-order expressibility is always guaranteed. We conclude by extending our positive results to DL-Lite ontologies without inverse.read more
Citations
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Book ChapterDOI
Ontology-Mediated Query Answering with Data-Tractable Description Logics
Meghyn Bienvenu,Magdalena Ortiz +1 more
TL;DR: A brief introduction to ontology-mediated query answering using description logic (DL) ontologies, with a focus on DLs for which query answering scales polynomially in the size of the data, as these are best suited for applications requiring large amounts of data.
Proceedings Article
Tractable approximations of consistent query answering for robust ontology-based data access
Meghyn Bienvenu,Riccardo Rosati +1 more
TL;DR: This paper proposes two new families of inconsistency-tolerant semantics which approximate the CQA semantics from above and from below and converge to it in the limit, and shows a general tractability result for all known first-order rewritable ontology languages.
Journal ArticleDOI
Inconsistency-tolerant query answering in ontology-based data access
TL;DR: This work proposes a different repair-based semantics, and shows that query answering under the new semantics is first-order rewritable in OBDA, even if the ontology is expressed in one of the most expressive members of the DL-Lite family.
Proceedings Article
Querying Inconsistent Description Logic Knowledge Bases under Preferred Repair Semantics (Extended Abstract)
TL;DR: This paper studies variants of two popular inconsistency-tolerant semantics obtained by replacing classical repairs by various types of preferred repair, and proposes an approach combining incomplete tractable methods with calls to a SAT solver.
Proceedings Article
From classical to consistent query answering under existential rules
TL;DR: This work performs an in-depth analysis of the complexity of consistent query answering under the main decidable classes of existential rules enriched with negative constraints, and focuses on one of the most prominent inconsistency-tolerant semantics, namely, the AR semantics.
References
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Journal ArticleDOI
Tractable Reasoning and Efficient Query Answering in Description Logics: The DL-Lite Family
TL;DR: It is shown that, for the DLs of the DL-Lite family, the usual DL reasoning tasks are polynomial in the size of the TBox, and query answering is LogSpace in thesize of the ABox, which is the first result ofPolynomial-time data complexity for query answering over DL knowledge bases.
Proceedings Article
Pushing the EL envelope
TL;DR: This work identifies a set of expressive means that can be added to EL without sacrificing tractability, and shows that basically all other additions of typical DL constructors to EL with GCIs make subsumption intractable, and in most cases even EXPTIME-complete.
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Elements of Finite Model Theory
TL;DR: This book describes applications in databases, complexity theory, and formal languages, as well as other branches of computer science, and highlights the computer science aspects of the subject.
Proceedings ArticleDOI
Consistent query answers in inconsistent databases
TL;DR: The problem of the logical characterization of the notion of consistent answer in a relational database that may violate given integrity constraints is considered and its soundness and completeness are proved.
Journal Article
Consistent query answers in inconsistent databases
TL;DR: In this article, the authors consider the problem of the logical characterization of the notion of consistent answer in a relational database that may violate given integrity constraints and present a method for computing consistent answers.