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Abstract

Thesauri are used to provide controlled vocabularies for resource classification. Their use can greatly assist document discovery because thesauri man date a consistent shared terminology for describing documents. A particular thesauras classifies documents according to an information community's needs. As a result, there are many different thesaural schemas. This has led to a proliferation of schema-specific thesaural systems. In our research, we exploit schematic regularities to design a generic thesaural ontology and specfiy it as a markup language. The language provides a common representational framework in which to encode the idiosyncrasies of specific thesauri. This approach has several advantages: it offers consistent syntax and semantics in which to express thesauri; it allows general purpose thesaural applications to leverage many thesauri; and it supports a single thesaural user interface by which information communities can consistently organise, score and retrieve electronic documents.

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Abstract

With networked information access to heterogeneous data sources, the problem of terminology provision and interoperability of controlled vocabulary schemes such as thesauri becomes increasingly urgent. Solutions are needed to improve the performance of full-text retrieval systems and to guide the design of controlled terminology schemes for use in structured data, including metadata. Thesauri are created in different languages, with different scope and points of view and at different levels of abstraction and detail, to accomodate access to a specific group of collections. In any wider search accessing distributed collections, the user would like to start with familiar terminology and let the system find out the correspondences to other terminologies in order to retrieve equivalent results from all addressed collections. This paper investigates possible semantic differences that may hinder the unambiguous mapping and transition from one thesaurus to another. It focusses on the differences of meaning of terms and their relations as intended by their creators for indexing and querying a specific collection, in contrast to methods investigating the statistical relevance of terms for objects in a collection. It develops a notion of optimal mapping, paying particular attention to the intellectual quality of mappings between terms from different vocabularies and to problems of polysemy. Proposals are made to limit the vagueness introduced by the transition from one vocabulary to another. The paper shows ways in which thesaurus creators can improve their methodology to meet the challenges of networked access of distributed collections created under varying conditions. For system implementers, the discussion will lead to a better understanding of the complexity of the problem

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Date

24. 8.2005 19:20:22

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Date

26.12.2011 13:22:07

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Content

Dieser Aufsatz ist kein Abgesang auf MeSH (= Medical Subject Headings in Medline/PubMed), wie man/frau vielleicht vermuten könnte. Vielmehr wird - ohne informatiklastiges Fachchinesisch - an Hand des von der National Library of Medicine entwickelten Unified Medical Language System erklärt, worin die Anforderungen an Ontologien bestehen, die im Zusammenhang mit dem Semantic Web allerorten eingefordert und herbeigewünscht werden. Eine Lektüre für Einsteigerinnen, die zum Vertiefen der gewonnenen Begriffssicherheit an Hand der weiterführenden Literaturhinweise anregt. Da das UMLS hier vor allem als Beispiel verwendet wird, werden auch Bibliothekarlnnen, Dokumentarlnnen und Informationsspezialistinnen anderer Fachbereiche den Aufsatz mit Gewinn lesen - und erfahren, dass unser Fachwissen aus der Sacherschließung und der Verwendung und Mitgestaltung von Normdateien und Thesauri bei der Entwicklung von Ontologien gefragt ist! (Eveline Pipp, Universitätsbibliothek Innsbruck). - Die elektronische Version dieses Artikels ist verfügbar unter: http://www.egms.de/en/journals/mbi/2006-6/mbi000049.shtml.