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Content

Master thesis Master of Science (Library and Information Studies) (MSc), Universität Wien. Advisor: Christoph Steiner. Vgl.: https://www.researchgate.net/publication/371680244_Vergabe_von_DDC-Sachgruppen_mittels_eines_Schlagwort-Thesaurus. DOI: 10.25365/thesis.70030. Vgl. dazu die Präsentation unter: https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=web&cd=&ved=0CAIQw7AJahcKEwjwoZzzytz_AhUAAAAAHQAAAAAQAg&url=https%3A%2F%2Fwiki.dnb.de%2Fdownload%2Fattachments%2F252121510%2FDA3%2520Workshop-Gabler.pdf%3Fversion%3D1%26modificationDate%3D1671093170000%26api%3Dv2&psig=AOvVaw0szwENK1or3HevgvIDOfjx&ust=1687719410889597&opi=89978449.

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Abstract

This dissertation studies ontology mapping: the problem of finding semantic correspondences between similar elements of different ontologies. In the dissertation, elements denote classes or properties of ontologies. The goal of this research is to use ontology mapping to make heterogeneous information more accessible. The World Wide Web (WWW) now is widely used as a universal medium for information exchange. Semantic interoperability among different information systems in the WWW is limited due to information heterogeneity, and the non semantic nature of HTML and URLs. Ontologies have been suggested as a way to solve the problem of information heterogeneity by providing formal, explicit definitions of data and reasoning ability over related concepts. Given that no universal ontology exists for the WWW, work has focused on finding semantic correspondences between similar elements of different ontologies, i.e., ontology mapping. Ontology mapping can be done either by hand or using automated tools. Manual mapping becomes impractical as the size and complexity of ontologies increases. Full or semi-automated mapping approaches have been examined by several research studies. Previous full or semiautomated mapping approaches include analyzing linguistic information of elements in ontologies, treating ontologies as structural graphs, applying heuristic rules and machine learning techniques, and using probabilistic and reasoning methods etc. In this paper, two generic ontology mapping approaches are proposed. One is the PRIOR+ approach, which utilizes both information retrieval and artificial intelligence techniques in the context of ontology mapping. The other is the non-instance learning based approach, which experimentally explores machine learning algorithms to solve ontology mapping problem without requesting any instance. The results of the PRIOR+ on different tests at OAEI ontology matching campaign 2007 are encouraging. The non-instance learning based approach has shown potential for solving ontology mapping problem on OAEI benchmark tests.

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Abstract

In Zeiten, in denen der schnelle und einfache Zugriff auf strukturierte und umfangreiche Datenbestände zunehmend an Bedeutung gewinnt, stellt die Heterogenität eben dieser Bestände ein großes Problem dar. Die meisten Bibliothekskataloge, Datenbanken usw. sind inhaltlich durch unterschiedliche Instrumente erschlossen, was für den Benutzer eine gewisse Einarbeitungszeit in jedes Erschließungsinstrument sowie die Notwendigkeit zur wiederholten und neu formulierten Suche in den unterschiedlich erschlossenen Datenbeständen bedeutet. Als Möglichkeit zur Behandlung der Heterogenitätsproblematik kommen beispielsweise Crosskonkordanzen in Betracht, durch welche semantisch übereinstimmende Schlagwörter, Deskriptoren bzw. Notationen verschiedener Erschließungsinstrumente intellektuell miteinander verbunden werden, so dass mit identischer Suchfrage mehrere unterschiedlich erschlossene Datenbestände durchsucht werden können. In der vorliegenden Arbeit soll die Problematik heterogener Datenbestände sowie die Behandlungsmöglichkeit durch Crosskonkordanzen beschrieben werden. Die konkretisierende Darstellung erfolgt anhand des Projektes CrissCross, einem gemeinschaftlichen Projekt der Deutschen Nationalbibliothek und der Fachhochschule Köln, in dem Crosskonkordanzen zwischen den Erschließungsinstrumenten SWD, DDC sowie LCSH und RAMEAU erstellt werden. Besonderheiten des Projektes CrissCross sind neben der Multilingualität und der Verbindung von verbalen und klassifikatorischen Erschließungsinstrumenten auch eine intellektuelle Gewichtung der Beziehungsstärke zweier verknüpfter Terme, die so genannte Determiniertheit. Neben den integrierten Erschließungsinstrumenten wird auch die konkrete Vorgehensweise ihrer Verbindung erläutert. Des Weiteren werden die Problemfelder des Projektes und im Besonderen denkbare Einsatzmöglichkeiten der Projektergebnisse vorgestellt, die wesentlich zur Lösung der Heterogenitätsproblematik und somit zu einer Verbesserung des Retrievals für den Benutzer beitragen können.

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Abstract

Diese These, dass die Versionierung der DDC zu einer verbesserten Suche führt, soll in dieser Arbeit untersucht werden. Es soll geprüft werden, ob die vorgeschlagene Vorgehensweise zu einem besseren Retrievalergebnis führt. Die Arbeit wird zunächst einen Überblick über die theoretischen Hintergründe von inhaltlicher Erschließung und den technischen Methoden liefern, bevor das eigentliche Problem anhand einer Testdatenbank und entsprechender Suchanfragen behandelt wird.

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Pages

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Abstract

The integration of metadata from distinct, heterogeneous data sources requires metadata interoperability, which is a qualitative property of metadata information objects that is not given by default. The technique of metadata mapping allows domain experts to establish metadata interoperability in a certain integration scenario. Mapping solutions, as a technical manifestation of this technique, are already available for the intensively studied domain of database system interoperability, but they rarely exist for the Web. If we consider the amount of steadily increasing structured metadata and corresponding metadata schemes on theWeb, we can observe a clear need for a mapping solution that can operate in aWeb-based environment. To achieve that, we first need to build its technical core, which is a mapping model that provides the language primitives to define mapping relationships. Existing SemanticWeb languages such as RDFS and OWL define some basic mapping elements (e.g., owl:equivalentProperty, owl:sameAs), but do not address the full spectrum of semantic and structural heterogeneities that can occur among distinct, incompatible metadata information objects. Furthermore, it is still unclear how to process defined mapping relationships during run-time in order to deliver metadata to the client in a uniform way. As the main contribution of this thesis, we present an abstract mapping model, which reflects the mapping problem on a generic level and provides the means for reconciling incompatible metadata. Instance transformation functions and URIs take a central role in that model. The former cover a broad spectrum of possible structural and semantic heterogeneities, while the latter bind the complete mapping model to the architecture of the Word Wide Web. On the concrete, language-specific level we present a binding of the abstract mapping model for the RDF Vocabulary Description Language (RDFS), which allows us to create mapping specifications among incompatible metadata schemes expressed in RDFS. The mapping model is embedded in a cyclic process that categorises the requirements a mapping solution should fulfil into four subsequent phases: mapping discovery, mapping representation, mapping execution, and mapping maintenance. In this thesis, we mainly focus on mapping representation and on the transformation of mapping specifications into executable SPARQL queries. For mapping discovery support, the model provides an interface for plugging-in schema and ontology matching algorithms. For mapping maintenance we introduce the concept of a simple, but effective mapping registry. Based on the mapping model, we propose aWeb-based mediator wrapper-architecture that allows domain experts to set up mediation endpoints that provide a uniform SPARQL query interface to a set of distributed metadata sources. The involved data sources are encapsulated by wrapper components that expose the contained metadata and the schema definitions on the Web and provide a SPARQL query interface to these metadata. In this thesis, we present the OAI2LOD Server, a wrapper component for integrating metadata that are accessible via the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH). In a case study, we demonstrate how mappings can be created in aWeb environment and how our mediator wrapper architecture can easily be configured in order to integrate metadata from various heterogeneous data sources without the need to install any mapping solution or metadata integration solution in a local system environment.