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This paper presents the vision and results of creating a national level cross-domain ontology and ontology service infrastructure in Finland. The novelty of the infrastructure is based on two ideas. First, a system of open source core ontologies is being developed by transforming thesauri into mutually aligned lightweight ontologies, including a large top ontology that is extended by various domain specific ontologies. Second, the ONKI Ontology Server framework for publishing ontologies as ready to use services has been designed and implemented. ONKI provides legacy and other applications with ready to use functionalities for using ontologies on the HTML level by Ajax and semantic widgets. The idea is to use ONKI for creating mash-up applications in a way analogous to using Google or Yahoo Maps, but in our case external applications are mashed-up with ontology support.

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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.

Abstract. CULTURESAMPO is an application demonstration of a national level publication system of cultural heritage contents on the Web, based on ideas and technologies of the Semantic (Web and) Web 2.0. On the semantic side, the system presents new solutions to interoperability problems of dealing with multiple ontologies of different domains, and to problems of integrating multiple metadata schemas and cross-domain content into a homogeneous semantic portal. A novelty of the system is to use semantic models based on events and narrative process descriptions for modeling and visualizing cultural phenomena, and for semantic recommendations. On the Web 2.0 side, CULTURESAMPO proposes and demonstrates a content creation process for collaborative, distributed ontology and content development including different memory organizations and citizens. The system provides the cultural heritage contents to end-users in a new way through multiple (nine) thematic perspectives, based on semantic visualizations. Furthermore, CULTURESAMPO services are available for external web-applications to use through semantic AJAX widgets. A Basis for Cultural Heritage on the Semantic WebIn our view, a cross-domain semantic cultural heritage portal [1] should be built on three pillars: First we need a cross-domain content infrastructure of ontologies, metadata standards, and related services, that is developed and maintained on a global level through collaborative local efforts. Second, the process of producing ontologically harmonized metadata should be organized in a collaborative fashion, where distributed content producers create semantically correct annotations cost-efficiently through centralized services. Third, the contents should be made available to human end-users and machines thought intelligent search, browsing, and visualization techniques. For machines, easy to use mash-up APIs and web services should be available. In this way, the collaboratively aggregated, semantically enriched knowledge base can be exposed and reused easily as services in other portals and applications in the same vein as Google Ads or Maps 1 .1

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.

This paper presents the results of a pilot study on using automatic text categorization techniques in identifying online sexual predators. We report on our SVM and k-NN models. Our distance weighted k-NN classifier reaches an f-measure of 0.943 on test data distinguishing the child and the victim sides of text chats between sexual predators and volunteers posing as underage victims.

Many semantic portals use faceted browsing, where the facets are based on the underlying indexing ontologies of the content. However, in many cases, like in medical applications, the ontologies may be very large and complex, and do not provide the end-user with intuitive facet hierarchies for conceptualizing the content, for formulating queries, and for classifying the search results. We argue that in such cases end-user facets should be separated from the annotation ontologies, and show how to generalize the semantic view-based search paradigm to take into account this fact. A user-centric card sorting method is proposed for designing intuitive views for the end-users and a method for mapping its facets onto the indexing ontologies and search items is presented. The system has been implemented in a prototype of the semantic portal TerveSuomi.fi, a national health promotion portal in Finland.