Semantic Web data with annotations is becoming available, being YAGO knowledge base a prominent example. In this paper we present an approach to perform the closure of large RDF Schema annotated semantic web data using standard database technology. In particular, we exploit several alternatives to address the problem of computing transitive closure with real fuzzy semantic data extracted from Y...

This paper discusses a vision of the Semantic Web for learning resources and some problems found. We consider RDF as the first step to the Semantic Web. But using all the possibilities of RDF is not that simple. Constructing an RDF schema for a given metadata schema, translating RDF descriptions and querying a set of descriptions are the main problems we discuss here. The example of the LOM (Le...

One of the major problems in the realization of the vision of the “Semantic Web” is the transformation of existing web data into sources that can be processed and used by machines. This paper presents a procedure that can be used to turn XML documents into knowledge structures, by interpreting them as RDF data via an RDF-Schema specification. This allows semantic annotation of XML documents via...

An RDF graph is, at its core, just a set of statements consisting of subjects, predicates and objects. Nevertheless, since its inception practitioners have asked for richer data structures such as containers (for open lists, sets and bags), collections (for closed lists) and reification (for quoting and provenance). Though this desire has been addressed in the RDF primer and RDF Schema specific...

We present a method for mapping security levels among the components of a distributed system where data in the local sources are represented in XML. Distributed data is integrated using a semantic-based approach that maps each XML schema into an RDF schema and subsequently integrates those schemas into a global RDF schema using a global as view (GAV) approach. We transform the security levels d...

The expressivity of RDF and RDF Schema that was described in [12] is deliberately very limited: RDF is (roughly) limited to binary ground predicates, and RDF Schema is (again roughly) limited to a subclass hierarchy and a property hierarchy, with domain and range definitions of these properties. However, the Web Ontology Working Group of W3C identified a number of characteristic use-cases for O...

To realize the vision of the Semantic Web, efficient storage and retrieval of large RDF data sets is required. A common technique for persisting RDF data (graphs) is to use a single relational database table, a triple store. But, we believe a single triple store cannot scale for large-scale applications. This paper describes storing and querying persistent RDF graphs in Jena, a Semantic Web pro...

The need for descriptive information, i.e., metadata, about Web resources has been recognized in several application contexts (e.g., digital libraries, portals). The Resource Description Framework (RDF) aims at facilitating the creation and exchange of metadata, as directed labeled graphs serialized in XML. In particular, the de nition of schema vocabularies enables the interpretation of semist...

XML and RDF are different in many ways, but it is possible that some of the challenges that arose in designing a validation system for XML will have equivalents in the Semantic Web world. The purpose of this paper is to suggest a few such areas for consideration. In some cases, the nature of RDF itself will suggest design approaches different from those used for XML Schema, e.g. that schema inf...

Currently many tourism systems and standardisation initiatives adopt XML as a standard for data representation. Together with XML, XML Schema definition language is becoming more widely used for describing the structure and constraining the contents of the documents. However neither XML itself nor XML Schema provides sufficient mechanisms for the representation of data semantics. In this paper ...