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19
Query Answering for OWL-DL with Rules
- Journal of Web Semantics
, 2004
"... Both OWL-DL and function-free Horn rules are decidable fragments of first-order logic with interesting, yet orthogonal expressive power. A combination of OWL-DL and rules is desirable for the Semantic Web; however, it might easily lead to the undecidability of interesting reasoning problems. Here, w ..."
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Cited by 329 (28 self)
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Both OWL-DL and function-free Horn rules are decidable fragments of first-order logic with interesting, yet orthogonal expressive power. A combination of OWL-DL and rules is desirable for the Semantic Web; however, it might easily lead to the undecidability of interesting reasoning problems. Here, we present a decidable such combination where rules are required to be DL-safe: each variable in the rule is required to occur in a non-DL-atom in the rule body. We discuss the expressive power of such a combination and present an algorithm for query answering in the related logic SHIQ extended with DL-safe rules, based on a reduction to disjunctive programs.
Data Complexity of Reasoning in Very Expressive Description Logics
- IN PROC. IJCAI 2005
, 2005
"... Data complexity of reasoning in description logics (DLs) estimates the performance of reasoning algorithms measured in the size of the ABox only. We show that, even for the very expressive DL SHIQ, satisfiability checking is data complete for NP. For applications with large ABoxes, this can be a mor ..."
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Cited by 122 (20 self)
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Data complexity of reasoning in description logics (DLs) estimates the performance of reasoning algorithms measured in the size of the ABox only. We show that, even for the very expressive DL SHIQ, satisfiability checking is data complete for NP. For applications with large ABoxes, this can be a more accurate estimate than the usually considered combined complexity, which is EXPTIMEcomplete. Furthermore, we identify an expressive fragment, Horn-SHIQ, which is data complete for P, thus being very appealing for practical usage.
Reasoning in Description Logics using Resolution and Deductive Databases
, 2006
"... This dissertation was updated on 12.07.2006 to correct a couple of minor errors. The original version is available at the following address: ..."
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Cited by 100 (14 self)
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This dissertation was updated on 12.07.2006 to correct a couple of minor errors. The original version is available at the following address:
Resolution-based approximate reasoning for OWL DL
- PROC. ISWC-2005
, 2005
"... We propose a new technique for approximate ABox reasoning with OWL DL ontologies. Essentially, we obtain substantially improved reasoning performance by disregarding non-Horn features of OWL DL. Our approach comes as a side-product of recent research results concerning a new transformation of OWL D ..."
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Cited by 36 (10 self)
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We propose a new technique for approximate ABox reasoning with OWL DL ontologies. Essentially, we obtain substantially improved reasoning performance by disregarding non-Horn features of OWL DL. Our approach comes as a side-product of recent research results concerning a new transformation of OWL DL ontologies into negation-free disjunctive datalog [1,2,3,4], and rests on the idea of performing standard resolution over disjunctive rules by treating them as if they were non-disjunctive ones. We analyse our reasoning approach by means of non-monotonic reasoning techniques, and present an implementation, called Screech.
Integrating linear arithmetic into superposition calculus
- In Computer Science Logic (CSL’07
, 2007
"... Abstract. We present a method of integrating linear rational arithmetic into superposition calculus for first-order logic. One of our main results is completeness of the resulting calculus under some finiteness assumptions. 1 ..."
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Cited by 27 (3 self)
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Abstract. We present a method of integrating linear rational arithmetic into superposition calculus for first-order logic. One of our main results is completeness of the resulting calculus under some finiteness assumptions. 1
Uncertainty and description logic programs: A proposal . . .
- FUZZY LOGIC AND THE SEMANTIC WEB, CAPTURING INTELLIGENCE, CHAPTER 7
, 2004
"... Rule-based and object-oriented techniques are rapidly making their way into the infrastructure for representing and reasoning about the Semantic Web and combining these two paradigms emerges as an important objective. We present a new family of representation languages, which extents existing langua ..."
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Cited by 25 (8 self)
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Rule-based and object-oriented techniques are rapidly making their way into the infrastructure for representing and reasoning about the Semantic Web and combining these two paradigms emerges as an important objective. We present a new family of representation languages, which extents existing language families for the Semantic Web: namely Description Logic Programs (DLPs) and DLPs with uncertainty (µDLPs). The former combine the expressive power of description logics (which capture the meaning of the most popular features of structured representation of knowledge) and disjunctive logic programs (powerful rule-based representation languages). The latter are DLPs in which the management of uncertainty is considered as well. We show that µDLPs may be applied in the context of distributed information search in the Semantic Web, where the representation of the inherent uncertainty of the relationships among resource ontologies, to which an automated agent has access to, is required.
Ontology-Based User Context Management: The Challenges of Imperfection and Time-Dependence
- in On the Move to Meaningful Internet Systems 2006: CoopIS, DOA, GADA, and ODBASE. Part I., ser. Lecture
, 2006
"... Robust and scalable user context management is the key enabler for the emerging context- and situation-aware applications, and ontology-based approaches have shown their usefulness for capturing especially context information on a high level of abstraction. But so far the problem has not been app ..."
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Cited by 15 (3 self)
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Robust and scalable user context management is the key enabler for the emerging context- and situation-aware applications, and ontology-based approaches have shown their usefulness for capturing especially context information on a high level of abstraction. But so far the problem has not been approached as a data management problem, which is key to scalability and robustness. The specific challenges lie in the imperfection of high-level context information, its time-dependence and the variability in the dynamics between its different elements.
Description logics and disjunctive datalog -- the story so far
- PROC. INTERNATIONAL WORKSHOP ON DESCRIPTION LOGICS
, 2005
"... In this paper we present an overview of our recent work on the relationship between description logics and disjunctive datalog. In particular, we reduce satisfiability and instance checking in SHIQ to corresponding problems in disjunctive datalog. This allows us to apply practically successful deduc ..."
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Cited by 7 (0 self)
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In this paper we present an overview of our recent work on the relationship between description logics and disjunctive datalog. In particular, we reduce satisfiability and instance checking in SHIQ to corresponding problems in disjunctive datalog. This allows us to apply practically successful deductive database optimization techniques, such as magic sets. Interestingly, the reduction also allows us to obtain novel theoretical results on description logics. In particular, we show that the data complexity of reasoning in SHIQ is in NP, and we define a fragment called Horn-SHIQ for which the data complexity is in P. Finally, the reduction provides a basis for query answering in an extension of SHIQ with so-called DL-safe rules.
Description Logics and Disjunctive Datalog—More Than just a Fleeting Resemblance
- In Proc. of the 4th Workshop on Methods for Modalities (M4M4
, 2005
"... As applications of description logics (DLs) proliferate, efficient reasoning with large ABoxes (sets of individuals with descriptions) becomes ever more important. Motivated by the prospects of reusing optimization techniques of deductive databases, we developed a novel algorithm for reasoning in de ..."
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Cited by 2 (0 self)
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As applications of description logics (DLs) proliferate, efficient reasoning with large ABoxes (sets of individuals with descriptions) becomes ever more important. Motivated by the prospects of reusing optimization techniques of deductive databases, we developed a novel algorithm for reasoning in description logic, which reduces a DL knowledge base to a disjunctive datalog program without changing the set of relevant consequences. This allows to answer queries by applying optimization techniques, such as join-order optimizations or magic sets. The algorithm supports the very expressive logic SHIQ(D), so the reduction is quite technically involved. In this paper we present a simplified algorithm for the basic logic ALC. Whereas this algorithm is much easier to understand, it is based on the same principles as the general one. 1
Description logic programs: Normal forms
, 2004
"... An intersection of OWL with (function-free non-disjunctive) Datalog, called DLP (for Description Logic Programs), has recently been described [GHVD03, Vol04]. We provide normal forms for DLP in Description Logic syntax and in Datalog syntax. 1 ..."
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Cited by 2 (2 self)
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An intersection of OWL with (function-free non-disjunctive) Datalog, called DLP (for Description Logic Programs), has recently been described [GHVD03, Vol04]. We provide normal forms for DLP in Description Logic syntax and in Datalog syntax. 1
