Due to the openness and decentralization of the Web, mechanisms to represent and reason about the reliability of RDF data become essential. This paper embarks on a formal analysis of RDF data enriched with trust information by focusing on the characterization of its model-theoretic semantics and on the study of relevant reasoning problems. The impact of trust values on the computational complex...

Metadata plays an important role in successfully understanding and querying data on the web. A number of metadata management solutions have already been developed but each is tailored to specific kinds of metadata. The Resource Description Framework (RDF) is a generic, flexible and powerful model which is becoming the de-facto standard for metadata representation on the Web. Its adoption has cr...

This project, spacenamespace, offers an XML namespace and RDF vocabulary for geospatial annotation, with a scheme to represent a physical space as a unique URI, allowing it to be referred to and shared on the semantic web. It also provides an Instant Message bot interface, which uses a web API which returns RDF data serialised in XML, to explore, augment and annotate the RDF graph model. the us...

RDF has become very popular for semantic data publishing due to its flexible and universal graph-like data model. Thus, the ever-increasing size of RDF data collections raises the need for scalable distributed approaches. We endorse the usage of existing infrastructures for Big Data processing like Hadoop for this purpose. Yet, SPARQL query performance is a major challenge as Hadoop is not inte...

If heterogeneous information systems store documents to the ontology-based document repository, they have to provide ontology-based documents (i.e. semantic documents). In this paper, we present how ontology-based documents (XHTML+RDFa) can be provided. The RDFa markup is used for embedding exchangeable information in the RDF format within the XHTML documents. Before we can provide ontology-bas...

We propose a model for a Resource Description Format (RDF) database for interlinear glossed text (IGT) created from documents encoded in the Extensible Markup Language (XML) using markup metaschemas. A metaschema, constructed using the Semantic Interpretation Language (SIL) (Simons 2004) maps XML-encoded documents to a common semantically rich RDF database. The RDF database in turn can be searc...

In this paper we introduce Explorator, a tool for exploring the Semantic Web data by direct manipulation. Explorator implements a model of operations that is supported by a visual interface that enables the user, with minimal knowledge of RDF model, to explore an RDF database without a-priori knowledge of data domain. Consequently, it is well suited for tasks that involve information search, ex...

The reference reconciliation problem consists in deciding whether different identifiers refer to the same data, i.e., correspond to the same world entity. The L2R system exploits the semantics of a rich data model, which extends RDFS by a fragment of OWL-DL and SWRL rules. In L2R, the semantics of the schema is translated into a set of logical rules of reconciliation, which are then used to inf...