Results 1 - 10
of
22
Managing Uncertainty and Vagueness in Description Logics for the Semantic Web
, 2007
"... Ontologies play a crucial role in the development of the Semantic Web as a means for defining shared terms in web resources. They are formulated in web ontology languages, which are based on expressive description logics. Significant research efforts in the semantic web community are recently direct ..."
Abstract
-
Cited by 135 (14 self)
- Add to MetaCart
Ontologies play a crucial role in the development of the Semantic Web as a means for defining shared terms in web resources. They are formulated in web ontology languages, which are based on expressive description logics. Significant research efforts in the semantic web community are recently directed towards representing and reasoning with uncertainty and vagueness in ontologies for the Semantic Web. In this paper, we give an overview of approaches in this context to managing probabilistic uncertainty, possibilistic uncertainty, and vagueness in expressive description logics for the Semantic Web.
Ontologies and databases: The DL-Lite approach
- IN REASONING WEB, VOLUME 5689 OF LNCS
, 2009
"... Ontologies provide a conceptualization of a domain of interest. Nowadays, they are typically represented in terms of Description Logics (DLs), and are seen as the key technology used to describe the semantics of information at various sites. The idea of using ontologies as a conceptual view over d ..."
Abstract
-
Cited by 58 (34 self)
- Add to MetaCart
Ontologies provide a conceptualization of a domain of interest. Nowadays, they are typically represented in terms of Description Logics (DLs), and are seen as the key technology used to describe the semantics of information at various sites. The idea of using ontologies as a conceptual view over data repositories is becoming more and more popular, but for it to become widespread in standard applications, it is fundamental that the conceptual layer through which the underlying data layer is accessed does not introduce a significant overhead in dealing with the data. Based on these observations, in recent years a family of DLs, called DL-Lite, has been proposed, which is specifically tailored to capture basic ontology and conceptual data modeling languages, while keeping low complexity of reasoning and of answering complex queries, in particular when the complexity is measured w.r.t. the size of the data. In this article, we present a detailed account of the major results that have been achieved for the DL-Lite family. Specifically, we concentrate on DL-LiteA,id, an expressive member of this family, present algorithms for reasoning and query answering over DL-LiteA,id ontologies,
AN OVERVIEW OF UNCERTAINTY AND VAGUENESS IN DESCRIPTION LOGICS FOR THE SEMANTIC WEB
, 2006
"... Ontologies play a crucial role in the development of the Semantic Web as a means for defining shared terms in Web resources. They are formulated in web ontology languages, which are based on expressive description logics. Significant research efforts are recently directed towards representing and ..."
Abstract
-
Cited by 22 (7 self)
- Add to MetaCart
Ontologies play a crucial role in the development of the Semantic Web as a means for defining shared terms in Web resources. They are formulated in web ontology languages, which are based on expressive description logics. Significant research efforts are recently directed towards representing and reasoning with uncertainty and vagueness in ontologies for the Semantic Web. In this paper, we give an overview of probabilistic uncertainty, possibilistic uncertainty, and vagueness in expressive description logics for the Semantic Web.
Top-k retrieval in description logic programs under vagueness for the Semantic Web
- In Proc. SUM-2007
, 2007
"... Abstract. Description logics (DLs) and logic programs (LPs) are important representation languages for the Semantic Web. In this paper, we address an emerging problem in such languages, namely, the problem of evaluating ranked top-k queries. Specifically, we show how to compute the top-k answers in ..."
Abstract
-
Cited by 19 (6 self)
- Add to MetaCart
(Show Context)
Abstract. Description logics (DLs) and logic programs (LPs) are important representation languages for the Semantic Web. In this paper, we address an emerging problem in such languages, namely, the problem of evaluating ranked top-k queries. Specifically, we show how to compute the top-k answers in a datacomplexity tractable combination of DLs and LPs under vagueness. 1
S.: Scalable querying service over fuzzy ontologies
- In: International World Wide Web Conference (WWW 2008), Beijing
, 2008
"... Fuzzy ontologies are envisioned to be useful in the Semantic Web. Existing fuzzy ontology reasoners are not scalable enough to handle the scale of data that the Web provides. In this paper, we propose a framework of fuzzy query languages for fuzzy ontologies, and present query answering algorithms f ..."
Abstract
-
Cited by 19 (10 self)
- Add to MetaCart
(Show Context)
Fuzzy ontologies are envisioned to be useful in the Semantic Web. Existing fuzzy ontology reasoners are not scalable enough to handle the scale of data that the Web provides. In this paper, we propose a framework of fuzzy query languages for fuzzy ontologies, and present query answering algorithms for these query languages over fuzzy DL-Lite ontologies. Moreover, this paper reports on implementation of our approach in the fuzzy DL-Lite query engine in the ONTOSEARCH2 system and preliminary, but encouraging, benchmarking results. To the best of our knowledge, this is the first ever scalable query engine for fuzzy ontologies. Categories and Subject Descriptors
Tightly integrated probabilistic description logic programs for the semantic web
- In Proc. ICLP-2007
, 2007
"... Abstract. Creating mappings between ontologies is a common way of approaching the semantic heterogeneity problem on the Semantic Web. To fit into the landscape of semantic web languages, a suitable, logic-based representation formalism for mappings is needed. We argue that such a formalism has to be ..."
Abstract
-
Cited by 13 (5 self)
- Add to MetaCart
(Show Context)
Abstract. Creating mappings between ontologies is a common way of approaching the semantic heterogeneity problem on the Semantic Web. To fit into the landscape of semantic web languages, a suitable, logic-based representation formalism for mappings is needed. We argue that such a formalism has to be able to deal with uncertainty and inconsistencies in automatically created mappings. We analyze the requirements for such a formalism, and we propose a novel approach to probabilistic description logic programs as such a formalism, which tightly combines disjunctive logic programs under the answer set semantics with both description logics and Bayesian probabilities. We define the language, and we show that it can be used to resolve inconsistencies and merge mappings from different matchers based on the level of confidence assigned to different rules. Furthermore, we explore the computational aspects of consistency checking and query processing in tightly integrated probabilistic description logic programs. We show that these problems are decidable and computable, respectively, and that they can be reduced to consistency checking and cautious/brave reasoning, respectively, in tightly integrated disjunctive description logic programs. We also analyze the complexity of consistency checking and query processing in the new probabilistic description logic programs in special cases. In particular, we present a special case of these problems with polynomial data complexity. 1
DLMedia: An ontology mediated multimedia information retrieval system
- IN: PROC. DL-2007
, 2007
"... We outline DLMedia, an ontology mediated multimedia information retrieval system, which combines logic-based retrieval with multimedia featurebased similarity retrieval. An ontology layer may be used to define (in terms of a DLR-Lite like description logic) the relevant abstract concepts and relati ..."
Abstract
-
Cited by 8 (5 self)
- Add to MetaCart
(Show Context)
We outline DLMedia, an ontology mediated multimedia information retrieval system, which combines logic-based retrieval with multimedia featurebased similarity retrieval. An ontology layer may be used to define (in terms of a DLR-Lite like description logic) the relevant abstract concepts and relations of the application domain, while a content-based multimedia retrieval system is used for feature-based retrieval.
Towards vague query answering in logic programming for logicbased information retrieval
- in: World Congress of the International Fuzzy Systems Association (IFSA-07
, 2007
"... Abstract. We address a novel issue for logic programming, namely the problem of evaluating ranked top-k queries. The problem occurs for instance, when we al-low queries such as “find cheap hotels close to the conference location ” in which vague predicates like cheap and close occur. Vague predicate ..."
Abstract
-
Cited by 7 (7 self)
- Add to MetaCart
Abstract. We address a novel issue for logic programming, namely the problem of evaluating ranked top-k queries. The problem occurs for instance, when we al-low queries such as “find cheap hotels close to the conference location ” in which vague predicates like cheap and close occur. Vague predicates have the effect that each tuple in the answer set has now a score in [0,1]. We show how to compute the top-k answers in case the set of facts is huge, without evaluating all the tuples.
Vague knowledge bases for matchmaking in P2P e-marketplaces
- IN: PROC. ESWC-2007
, 2007
"... In this paper we propose an approach to semantic matchmaking that exploits various knowledge representation technologies to find most promising partners in peer-to-peer e-marketplaces. In particular we mix in a formal and principled way the semantic expressiveness of DLR-lite Logic Programs, fuzzy l ..."
Abstract
-
Cited by 6 (2 self)
- Add to MetaCart
In this paper we propose an approach to semantic matchmaking that exploits various knowledge representation technologies to find most promising partners in peer-to-peer e-marketplaces. In particular we mix in a formal and principled way the semantic expressiveness of DLR-lite Logic Programs, fuzzy logic and utility theory. We adopt DLR-Lite Logic Programs to obtain a reasonable compromise between expressiveness and complexity to ensure the scalability of our approach to large e-marketplaces, and Fuzzy Logic to model logical specifications as soft constraints. Furthermore, fully exploiting the peer-to-peer paradigm, we consider in the matchmaking process preferences and corresponding utilities of both parties.
Employing DL-LiteR-Reasoners for Fuzzy Query Answering?
"... Abstract. Fuzzy Description Logics generalize crisp ones by providing membership degree semantics for concepts and roles by fuzzy sets. Re-cently, answering of conjunctive queries has been investigated and imple-mented in optimized reasoner systems based on the rewriting approach for crisp DLs. In t ..."
Abstract
-
Cited by 2 (2 self)
- Add to MetaCart
(Show Context)
Abstract. Fuzzy Description Logics generalize crisp ones by providing membership degree semantics for concepts and roles by fuzzy sets. Re-cently, answering of conjunctive queries has been investigated and imple-mented in optimized reasoner systems based on the rewriting approach for crisp DLs. In this paper we investigate how to employ such exist-ing implementations for crisp query answering in DL-LiteR over fuzzy ontologies. To this end we give an extended rewriting algorithm for the case of fuzzy DL-LiteR-ABoxes that employs the one for crisp DL-LiteR and investigate the limitations of this approach. We also tested the per-formance of our proto-type implementation FLite of this method. 1
