Principles of database and knowledge-base systems, Vol. I
Principles of database and knowledge-base systems, Vol. I
Algebraic optimization of object-oriented query languages
ICDT Selected papers of the 4th international conference on Database theory
The object data standard: ODMG 3.0
The object data standard: ODMG 3.0
XAL: an algebra for XML query optimization
ADC '02 Proceedings of the 13th Australasian database conference - Volume 5
The Semantic Web: The Roles of XML and RDF
IEEE Internet Computing
TRIPLE - A Query, Inference, and Transformation Language for the Semantic Web
ISWC '02 Proceedings of the First International Semantic Web Conference on The Semantic Web
RDF Aggregate Queries and Views
ICDE '05 Proceedings of the 21st International Conference on Data Engineering
SPARQ2L: towards support for subgraph extraction queries in rdf databases
Proceedings of the 16th international conference on World Wide Web
Product Life-Cycle Metadata Modeling and Its Application with RDF
IEEE Transactions on Knowledge and Data Engineering
Cardinality estimation for the optimization of queries on ontologies
ACM SIGMOD Record
Semantics and complexity of SPARQL
ACM Transactions on Database Systems (TODS)
RCQ-GA: RDF Chain Query Optimization Using Genetic Algorithms
EC-Web 2009 Proceedings of the 10th International Conference on E-Commerce and Web Technologies
An object-oriented based algebra for ontologies and their instances
ADBIS'07 Proceedings of the 11th East European conference on Advances in databases and information systems
Approximating query answering on RDF databases
World Wide Web
A query language for logic architectures
PSI'09 Proceedings of the 7th international Andrei Ershov Memorial conference on Perspectives of Systems Informatics
Ant colony optimization for RDF chain queries for decision support
Expert Systems with Applications: An International Journal
RCQ-ACS: RDF Chain Query Optimization Using an Ant Colony System
WI-IAT '12 Proceedings of the The 2012 IEEE/WIC/ACM International Joint Conferences on Web Intelligence and Intelligent Agent Technology - Volume 01
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To make the World Wide Web machine-understandable there is a strong demand both for languages describing metadata and for languages querying metadata. The Resource Description Framework (RDF), a language proposed by W3C, can be used for describing metadata about (Web) resources. RDF Schema (RDFS) extends RDF by providing means for creating application specific vocabularies (ontologies). While the two above languages are widely acknowledged as a standard means for describing Web metadata, a standardized language for querying RDF metadata is still an open issue. Research groups coming both from industry and academia are presently involved in proposing several RDF query languages. Due to the lack of an RDF algebra such query languages use APIs to describe their semantics and optimization issues are mostly neglected. This paper proposes RAL (an RDF algebra) as a reference mathematical study for RDF query languages and for performing RDF query optimization. We define the data model, we present the operators to manipulate the data, and we address the application of RAL for query optimization. RAL includes: extraction operators to retrieve the needed resources from the input RDF model, loop operators to support repetition, and construction operators to build the resulting RDF model.