Catálogo de publicaciones - libros

This paper deals with some modeling aspects that have to be addressed in the context of the integration of heterogeneous and autonomous XML resources. We propose an integration system, but the emphasis of this paper is neither on its algorithmic aspects nor on its technical details. Instead, we focus on the significance of offering appropriate high-level primitives and mechanisms for representing the semantics of XML data. We posit that support for such primitives and mechanisms is a pre-requisite for realizing the goals of the semantic Web .

Describing web resources using formal knowledge (i.e., creating metadata according to a formal representation of a domain of discourse) is the essence of the next evolution step of the Web, termed the Semantic Web. The W3C’s RDF/S (Resource Description Framework/Schema Language) enables the creation and exchange of resource metadata as normal web data. In this paper, we investigate the use of RDFS schemas as a means of knowledge representation and exchange in diverse application domains. In order to reason about the quality of existing RDF schemas, a benchmark serves as the basis of a statistical analysis performed with the aid of VRP, the Validating RDF Parser. The statistical data extracted lead to corollaries about the size and the morphology of RDF/S schemas. Furthermore, the study of the collected schemas draws useful conclusions about the actual use of RDF modeling constructs and frequent misuses of RDF/S syntax and/or semantics.

The semantic discontinuity between World-Wide Web languages, e.g., XML, XML Schema, and XPath, and Semantic Web languages, e.g., RDF, RDFS, and DAML+OIL, forms a serious barrier for the stated goals of the Semantic Web. This discontinuity results from a difference in modeling foundations between XML and logics. We propose to eliminate that discontinuity by creating a common semantic foundation for both the World-Wide Web and the Semantic Web, taking ideas from both. The common foundation results in essentially no change to XML, and only minor changes to RDF. But it allows the Semantic Web to get closer to its goal of describing the semantics of the World Wide Web. Other Semantic Web languages (including RDFS and DAML+OIL) are considerably changed because of this common foundation.

This paper describes an approach to derive assessments about information sources based on individual feedback about the sources. We describe TRELLIS, a system that helps users annotate their analysis of alternative information sources that can be contradictory and incomplete. As the user makes a decision on which sources to dismiss and which to believe in making a final decision, TRELLIS captures the derivation of the decision in a semantic markup. TRELLIS then uses these annotations to derive an assessment of the source based on the annotations of many individuals. Our work builds on the Semantic Web and presents a tool that helps users create annotations that are in a mix of formal and human language, and exploits the formal representations to derive measures of trust in the content of Web resources and their original source.

Ontologies are set to play a key role in the Semantic Web, and several web ontology languages, like DAML+OIL, are based on DLs. These not only provide a clear semantics to the ontology languages, but allows them to exploit DL systems in order to provide correct and complete reasoning services. Recent results shown that DL systems can be enriched by a conjunctive query language, providing a solution to one of the weakness of traditional DL systems. These results can be transfered to the Semantic Web community, where the need for expressive query languages is witnessed by different proposals (like DQL for DAML+OIL). In this paper we present a logical framework for conjunctive query answering in DAML+OIL. Moreover, we provide a sound and complete algorithm based on recent Description Logic research.

Product configuration is a key technology in today’s highly specialized economy. Within the scope of state-of-the-art B2B frameworks and eProcurement solutions, various initiatives take into account the provision of configuration services. However, they all are based on the idea of defining quasi-standards for many-to-many relationships between customers and vendors. When moving towards networked markets, where suppliers dynamically form supply-side consortia, more flexible approaches to B2B integration become necessary. The emerging paradigm of Web services has therefore a huge potential in business application integration. This paper presents an application scenario for configuration Web services, that is currently under development in the research project CAWICOMS^1. An ontology-based approach allows the advertisement of services and a configuration specific protocol defines the operational processes. However, the lack of standards for the semantic annotation of Web services is still a major shortcoming of current Web technology.

The Semantic Web would enable new ways of doing business on the Web that require development of advanced business document integration technologies performing intelligent document transformation. The documents use different vocabularies that consist of large hierarchies of terms. Accordingly, vocabulary mapping and transformation becomes an important task in the whole business document transformation process. It includes several subtasks: map discovery, map representation, and map execution that must be seamlessly integrated into the document integration process. In this paper we discuss the process of discovering the maps between two vocabularies assuming availability of two sets of documents, each using one of the vocabularies. We take the vocabularies of product classification codes as a playground and propose a reusable map discovery technique based on Bayesian text classification approach. We show how the discovered maps can be integrated into the document transformation process.

Ontologies now play an important role for enabling the semantic web. They provide a source of precisely defined terms e.g. for knowledge-intensive applications. The terms are used for concise communication across people and applications. Typically the development of ontologies involves collaborative efforts of multiple persons. OntoEdit is an ontology editor that integrates numerous aspects of ontology engineering. This paper focuses on collaborative development of ontologies with OntoEdit which is guided by a comprehensive methodology.

Many RDF repositories have already been implemented with various access languages and mechanisms. The aim of the EDUTELLA framework is to allow communication between different RDF repository implementations. Part of EDUTELLA is a Query Exchange Language (QEL) which can be used as lingua franca to retrieve information from RDF repositories. This work shows why we also need standardization of distributed modification capabilities. We describe use case scenarios for annotation and replication services and use them as guideline for our approach towards a Modification Exchange Language (MEL) for distributed RDF repositories.

The advantage of the RDF/DAML+OIL family of languages over ordinary XML is that it is topic-neutral and composable. However, its expressivity is severely limited. This limitation is well known, and the usual remedy is reification , in which RDF is used to describe formulas in a richer language. We propose a method for encoding typed predicate calculus using reification, which handles bound variables cleanly and causes the size to increase by only a constant multiple. The method generalizes to virtually any system, a claim which we illustrate by describing our program, PDDAML, which encodes domain specifications in PDDL using our technique. We argue that reification, while logically suspect, is in practice benign because any algorithm capable of doing inferences using logical notations can be easily extended to “unreify” those notations as needed. We also argue that the ability to represent predicate calculus on the semantic web is crucial.