Jeen Broekstra

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RDF and RDF Schema are two W3C standards aimed at enriching the Web with machine-processable semantic data. We have developed Sesame, an architecture for efficient storage and expressive querying of large quantities of metadata in RDF and RDF Schema. Sesame’s design and implementation are independent from any specific storage device. Thus, Sesame can be(More)
representation techniques. T he World Wide Web is possible because a set of widely established standards guarantees interoperability at various levels. Until now, the Web has been designed for direct human processing, but the next-generation Web, which Tim Berners-Lee and others call the “Semantic Web,” aims at machine-processible information.1 The Semantic(More)
RDF and RDF Schema provide the first W3C standard to enrich the Web with machine-processable semantic data. However, to be able to use this semantic data, a scalable, persistent RDF store and a powerful query engine using an expressive query language are needed. Sesame is an extensible architecture implementing both of these. Sesame can be based on(More)
This paper describes the design and implementation of Bibster, a Peer-to-Peer system for exchanging bibliographic data among researchers. Bibster exploits ontologies in data-storage, query formulation, query-routing and answer presentation: When bibliographic entries are made available for use in Bibster, they are structured and classified according to two(More)
Exploiting the full potential of the World Wide Web will require semantic as well as syntactic interoperability. This can best be achieved by providing a further representation and inference layer that builds on existing and proposed web standards. The OIL language extends the RDF schema standard to provide just such a layer. It combines the most attractive(More)
The purpose of this paper is to provide a rigorous comparison of six query languages for RDF. We outline and categorize features that any RDF query language should provide and compare the individual languages along these features. We describe several practical usage examples for RDF queries and conclude with a comparison of the expressiveness of the(More)
Recently, a widespread interest has emerged in using ontologies on the Web. RDF Schema (RDFS) is a basic tool that enables users to define vocabulary, structure and constraints for expressing metadata about Web resources. However, it includes no provisions for formal semantics, and its expressivity is not sufficient for full-fledged ontological modeling and(More)