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» Conjunctive Query Answering in SH using Knots
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EDBT
2006
ACM
121views Database» more  EDBT 2006»
14 years 7 months ago
A Decomposition-Based Probabilistic Framework for Estimating the Selectivity of XML Twig Queries
In this paper we present a novel approach for estimating the selectivity of XML twig queries. Such a technique is useful for approximate query answering as well as for determining...
Chao Wang, Srinivasan Parthasarathy, Ruoming Jin
ICDT
1999
ACM
97views Database» more  ICDT 1999»
13 years 11 months ago
Optimizing Large Join Queries in Mediation Systems
In data integration systems, queries posed to a mediator need to be translated into a sequence of queries to the underlying data sources. In a heterogeneous environment, with sour...
Ramana Yerneni, Chen Li, Jeffrey D. Ullman, Hector...
PVLDB
2010
151views more  PVLDB 2010»
13 years 5 months ago
Advanced Processing for Ontological Queries
Ontology-based data access is a powerful form of extending database technology, where a classical extensional database (EDB) is enhanced by an ontology that generates new intensio...
Andrea Calì, Georg Gottlob, Andreas Pieris
OTM
2007
Springer
14 years 1 months ago
Scalability of OWL Reasoning: Role condensates
In the last years, there has been an increasing interest in the performance of reasoning on the Semantic Web in presence of large ABoxes. Traditional reasoners make heavily use of ...
Sebastian Wandelt, Ralf Möller
CORR
2007
Springer
77views Education» more  CORR 2007»
13 years 7 months ago
Query Evaluation and Optimization in the Semantic Web
We address the problem of answering Web ontology queries efficiently. An ontology is formalized as a Deductive Ontology Base (DOB), a deductive database that comprises the ontology...
Edna Ruckhaus, Eduardo Ruiz, Maria-Esther Vidal