Résumé. Le développement du Web Sémantique a conduit à l’élaboration de standards pour la représentation des connaissances sur le Web. RDF, comme un de ces standards, est devenu une recommandation du W3C. Même s’il a été conçu pour être interprétable par l’homme et la machine (encodage XML, triplets, graphes étiquetés), RDF n’a pas été fourni avec des services d’interrogation et de raisonnement...

An unresolved issue in SWRL (the Semantic Web Rule Language) is whether the intended semantics of its RDF representation can be described as an extension of the W3C RDF semantics. In this paper we propose to make the model-theoretic semantics of SWRL compatible with RDF by interpreting SWRL rules in RDF graphs. For dealing with SWRL/RDF rules, we regard ‘Implies’ as an OWL class, and extract al...

SPARQL is the standard query language for Resource Description Framework (RDF) data. RDF was designed with the initial goal of developing metadata for the Internet. While the number and the size of the generated RDF datasets are continually increasing, most of today’s best RDF storage solutions are confined to a single node. Working on a single node has significant scalability issues, especiall...

A Roman dominating function (RDF) on a graphG = (V,E) is a function f : V −→ {0, 1, 2} satisfying the condition that every vertex u for which f(u) = 0 is adjacent to at least one vertex v for which f(v) = 2. The weight of an RDF is the value f(V (G)) = ∑ u∈V (G) f(u). An RDF f in a graph G is independent if no two vertices assigned positive values are adjacent. The Roman domination number γR(G)...

In the context of the Semantic Web, different approaches have been defined to represent RDF documents, and the selected representation affects storage and time complexity of the RDF data recovery and query processing tasks. This chapter addresses the problem of efficiently querying and storing RDF documents, and presents an alternative representation of RDF data, Bhyper, which is based on hyper...

An effort to utilize solid wastes at dumpsite as refuse-derived fuel (RDF) was carried out. The produced RDF briquette was then utilized in the gasification system. These wastes were initially examined for their physical composition and chemical characteristics. The wastes contained high plastic content of 24.6-44.8%, majority in polyethylene plastic bag form. The plastic wastes were purified b...

RDF has gained great interest in both academia and industry as an important language to describe graph data. Several approaches have been proposed for storing and querying RDF data efficiently; each works best under certain circumstances, e.g. certain types of data and/or queries. However, there was lack of a thorough understanding of exactly what these circumstances are, as different data-sets...

The basic data model for the Semantic Web is the Resource Description Framework (RDF). From a data management point of view, it resembles a lightweight knowledge base. In this paper we address updates in RDF. It is known that the semantics of updates for data models becomes unclear when the model turns, even slightly, more general than a simple relational structure. Viewing RDF as a knowledge b...

Many solutions have been developed to convert non-RDF data to RDF. A common task during this conversion is applying data manipulation functions to obtain the desired output. Depending on the data format of the source to be transformed, one can rely on the underlying technology, such as RDBMS for relational databases or XQuery for XML, to manipulate data to a certain extent while generating RDF....

Given the increasing prevalence of RDF data formats for storing and sharing data on the Semantic Web, efficient storage mechanisms for RDF data are also becoming increasingly important. We survey existing storage solutions for RDF data in an RDMS. Two recent and novel storage concepts open the door for significantly better querying efficiency. The first, proposed by Matono, et al (2005), models...