Raphael Volz

MAFRA - A MApping FRAmework for Distributed Ontologies

Ontologies as means for conceptualizing and structuring domain knowledge within a community of interest are seen as a key to realize the Semantic Web vision. However, the decentralized nature of the Web makes achieving this consensus across communities difficult, thus, hampering efficient knowledge sharing between them. In order to balance the autonomy of each community with the need for interoperability, mapping mechanisms between distributed ontologies in the Semantic Web are required. In this paper we present MAFRA, an interactive, incremental and dynamic framework for mapping distributed ontologies.

Ontologies for enterprise knowledge management

Several challenges exist related to applying ontologies in real-world environments. The authors present an integrated enterprise-knowledge management architecture, focusing on how to support multiple ontologies and manage ontology evolution.

KAON - Towards a Large Scale Semantic Web

The Semantic Web will bring structure to the content of Web pages, being an extension of the current Web, in which information is given a well-defined meaning. Especially within e-commerce applications, Semantic Web technologies in the form of ontologies and metadata are becoming increasingly prevalent and important. This paper introduce KAON - the Karlsruhe Ontology and Semantic WebTool Suite. KAON is developed jointly within several EU-funded projects and specifically designed to provide the ontology and metadata infrastructure needed for building, using and accessing semantics-driven applications on the Web and on your desktop.

Cooking the semantic web with the OWL API

This paper discusses issues that surround the provision of application support using OWL ontologies. It presents the OWL API, a high-level programmatic interface for accessing and manipulating OWL ontologies. We discuss the underlying design issues and illustrate possible solutions to technical issues occurring in systems that intend to support the OWL standard. Although the context of our solutions is that of a particular implementation, the issues discussed are largely independent of this and should be of interest to a wider community.

Migrating data-intensive web sites into the Semantic Web

The Semantic Web is intended to enable machine processability of web content and seems to be a solution for many drawbacks of the current Web. It is based on metadata that describe the formal semantics of Web contents. We present a novel, integrated and automated approach for migrating data-intensive Web applications into the Semantic Web. This approach can be applied to a broad range of todays business Web sites.

A comparison of RDF query languages

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 particular query languages. The use cases, sample data and queries for the respective languages are available on the web [6].

Visual modeling of OWL DL ontologies using UML

This paper introduces a visual, UML-based notation for OWL ontologies. We provide a standard MOF2 compliant metamodel which captures the language primitives offered by OWL DL. Similarly, we invent a UML profile, which allows to visually model OWL ontologies in a notation that is close to the UML notation. This allows to develop ontologies using UML tools. Throughout the paper, the significant differences to some earlier proposals for a visual, UML-based notation for ontologies are discussed.

An infrastructure for searching, reusing and evolving distributed ontologies

The vision of the Semantic Web can only be realized through proliferation of well-known ontologies describing different domains. To enable interoperability in the Semantic Web, it will be necessary to break these ontologies down into smaller, well-focused units that may be reused. Currently, three problems arise in that scenario. Firstly, it is difficult to locate ontologies to be reused, thus leading to many ontologies modeling the same thing. Secondly, current tools do not provide means for reusing existing ontologies while building new ontologies. Finally, ontologies are rarely static, but are being adapted to changing requirements. Hence, an infrastructure for management of ontology changes, taking into account dependencies between ontologies is needed. In this paper we present such an infrastructure addressing the aforementioned problems.

OntoWeb - A Semantic Web Community Portal

This paper describes a semantic portal through which knowledge can be gathered, stored, secured and accessed by members of a certain community. In particular, this portal takes into account companies and research institutes participating in the E.U. funded thematic network called OntoWeb. Ontology-based annotation of information is a prerequisite in order to offer the possibility of knowledge retrieval and extraction. The usage of well-defined semantics allows for the knowledge exchange between different OntoWeb community members. Thus, members are able to publish annotated information on the web, which is then crawled by a syndicator and stored in the portals knowledge base. The backbone of the portal architecture consists of a knowledge base in which the ontology and the instances are stored and maintained. In addition, ontology-boosted query mechanisms and presentation facilities are provided.

Views for light-weight Web ontologies

The Semantic Web aims at easy integration and usage of content by building on a semi-structured data model where data semantics are explicitly specified through ontologies. However, ontologies and thereby ontology-based applications themselves suffer from heterogeneity. Therefore a new level of data independence is required to allow the customization of information, e.g. towards the needs of other agents, which can be achieved by exploiting database view principles. This paper addresses this issue and presents a new view mechanism for the data models underlying the Semantic Web, RDF and RDFS.