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 in 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.

Currently, computers are changing from single, isolated devices into entry points to a worldwide network of information exchange and business transactions called the World Wide Web (WWW). For this reason, support in data, information, and knowledge exchange has become a key issue in current computer technology. The success of the WWW has made it increasingly difficult to find, access, present, and maintain the information required by a wide variety of users. In response to this problem, many new research initiatives and commercial enterprises have been set up to enrich available information with machine processable semantics. This semantic web will provide intelligent access to heterogeneous, distributed information, enabling software products (agents) to mediate between user needs and the information sources available. This paper summarizes ongoing research in the area of the semantic web, focusing especially on ontology technology.

One of the main hurdles towards a wide endorsement of ontologies is the high cost of constructing them. Reuse of existing ontologies offers a much cheaper alternative than building new ones from scratch, yet tools to support such reuse are still in their infancy. However, more ontologies are becoming available on the web, and online libraries for storing and indexing ontologies are increasing in number and demand. Search engines have also started to appear, to facilitate search and retrieval of online ontologies. This paper presents a fresh view on constructing ontologies automatically, by identifying, ranking, and merging fragments of online ontologies.

Abstract. This paper discusses problems of creating and using ontology library services in production use. One approach to a solution is presented with an online implementation—the Finnish Ontology Library Service ONKI — that is in pilot use on a national level in Finland. ONKI contributes to previous research on ontology libraries in many ways: First, mashup and web service support with various tools is provided for cost-efficient utilization of ontologies in indexing and search applications. Second, services covering the different phases of the ontology life cycle are provided. Third, the services are provided and used in real world applications on a national scale. Fourth, the ontology framework is being developed by a collaborative effort by organizations representing different application domains, such as health, culture, and business. 1

We present a national ontology library development framework ONKI under development in Finland. ONKI’s main goal is to support collaborative development and re-use of interdependent ontologies. It features change management and versioning of ontologies as well as a browser component which provides the ontology search and utilization services as Web Services.

The increasing number of ontologies on the Web and the appearance of large scale ontology repositories has brought the topic of ontology selection in the focus of the semantic web research agenda. Our view is that ontology evaluation is core to ontology selection and that, because ontology selection is performed in an open Web environment, it brings new challenges to ontology evaluation.

Abstract. Vocabularies are the building blocks of the Semantic Web providing shared terminological resources for content indexing, information retrieval, data exchange, and content integration. Most semantic web applications in practical use are based on lightweight ontologies and, more recently, on the Simple Knowledge Organization System (SKOS) data model being standardized by W3C. Easy and cost-efficient publication, integration, and utilization methods of vocabulary services are therefore highly important for the proliferation of the Semantic Web. This paper presents the ONKI SKOS Server for these tasks. Using ONKI SKOS, a SKOS vocabulary or a lightweight ontology can be published on the web as ready-to-use services in a matter of minutes. The services include not only a browser for human usage, but also Web Service and AJAX interfaces for concept finding, selecting and transporting resources from the ONKI SKOS Server to connected systems. Code generation services for AJAX and Web Service APIs are provided automatically, too. ONKI SKOS services are also used for semantic query expansion in information retrieval tasks. The idea of publishing ontologies as services is analogous to Google Maps. In our case, however, vocabulary services are provided and mashed-up in applications. ONKI SKOS was published in the beginning of 2008 and is to our knowledge the first generic SKOS server of its kind. The system has been used to publish and utilize some 60 vocabularies and ontologies in the National Finnish Ontology Service ONKI www.yso.fi. 1

The Semantic Web is based on using ontologies for enabling semantically disambiguated data exchange between distributed systems on the web. This requires efficient means for publishing ontologies on the web to ensure the availability, sharing and acceptance of the ontologies. Support services are needed for utilizing ontologies easily and costeffectively in applications and legacy systems lacking ontology support. To address these vital needs, this paper presents the ONKI ontology service which provides ready-to-use “mash-up ” functionalities, such as semantic disambiguation, concept finding and concept fetching as readyto-use web widgets for adding ontology support to e.g. HTML forms using JavaScript. Two implementations of the ONKI Server are presented: ONKI-SKOS for ontologies presented in the Simple Knowledge Organization System (SKOS) language and ONKI-Geo for geographical ontologies with a map interface. The presented ONKI systems are operational on the web, used in the National Finnish Ontology Service. They

Abstract. The field of economy and finance is a conceptually rich domain where information is complex, huge in volume and a highly valuable business product by itself. Novel management techniques are required for economic and financial information in order to enable an efficient generation, management and consumption of complex and big information resources. Following this direction, we have developed and ontology-based platform that provides a) the integration of contents and semantics in a knowledge base that provides a conceptual view on low-level contents, b) an adaptive hypermedia-based knowledge visualization and navigation system and c) semantic search facilities. We have developed, as the basis of this platform, an ontology for the domain of economic and financial information. 1

Web portals are entry points for information presentation and exchange over the Internet, used by a community of interest. Hence, they require an efficient support for communication and information sharing. Current Web technologies employed to build up these portals present serious limitations regarding information search, access, extraction, interpretation and processing. These limitations are naturally inherited by existing portals, thus hampering the communication and information sharing process between the community members. The application of Semantic Web technologies has the potential of overcoming these limitations and, therefore, these technologies can be used to evolve current Web portals into semantically enhanced Web portals. This paper presents the state of the art on the application of Semantic Web technologies to Web portals, points out the improvements achievable by the use of such technologies, and depicts requirements for future development of Semantic Web enabled Web portals. A wide coverage evaluation scheme and an evaluation criteria catalogue have been designed in order to consistently evaluate and compare existing Semantic Web portals.