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Abstract

There are many advantages for Digital Libraries in indexing with classifications or thesauri, but some current disincentive in the lack of flexible retrieval tools that deal with compound descriptors. This paper discusses a matching function for compound descriptors, or multi-concept subject headings, that does not rely an exact matching but incorporates term expansion via thesaurus semantic relationships to produce ranked results that take account of missing and partially matching terms. The matching function is based an a measure of semantic closeness between terms, which has the potential to help with recall problems. The work reported is part of the ongoing FACET project in collaboration with the National Museum of Science and Industry and its collections database. The architecture of the prototype system and its Interface are outlined. The matching problem for compound descriptors is reviewed and the FACET implementation described. Results are discussed from scenarios using the faceted Getty Art and Architecture Thesaurus. We argue that automatic traversal of thesaurus relationships can augment the user's browsing possibilities. The techniques can be applied both to unstructured multi-concept subject headings and potentially to more syntactically structured strings. The notion of a focus term is used by the matching function to model AAT modified descriptors (noun phrases). The relevance of the approach to precoordinated indexing and matching faceted strings is discussed.

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Content

Vortrag anläasslich des Workshops: "Extending the multilingual capacity of The European Library in the EDL project Stockholm, Swedish National Library, 22-23 November 2007".

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Abstract

Das CrissCross-Projekt verfolgt die Zielsetzung, ein erweitertes multilinguales und thesaurusbasiertes Registervokabular zur Dewey-Dezimalklassifikation (DDC Deutsch) zu erstellen, das als Recherchevokabulars zu heterogen erschlossenen Dokumenten verwendet werden kann und soll damit die Ausgangsbedingungen für die Gestaltung von OPAC-Retrievalumgebungen verbessern helfen. Im einzelnen soll jedes Sachschlagwort der Schlagwortnormdatei (SWD) eine DDC-Notation erhalten und es sollen die im Projekt MACS begonnen Arbeiten fortgesetzt werden, Links zwischen den Schlagwörtern der SWD, den Library of Congress Subject Headings (LCSH) und dem Répertoire d'autorité-matière encyclopédique et alphabétique unifé (Rameau) herzustellen. In diesem Beitrag wird der Vorschlag gemacht, die Zielsetzung des Projektes darin zu sehen, eine Kern-Ontologie mit universalen Relationen als Klassifikation zu benutzen und die beteiligten Normdateien als zugeordnete semantische Netze zu entwickeln, indem nicht-generische Relationen die Aufgabe der durch die Lokalisierung gestellten Anforderungen übernehmen. Generische Relationen im bekannten Thesaurussinn sind für derartige semantische Netze nicht mehr erforderlich, da sie sich aus den generischen Beziehungen der Kern-Ontologie vererben.

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Abstract

There are many advantages for Digital Libraries in indexing with classifications or thesauri, but some current disincentive in the lack of flexible retrieval tools that deal with compound descriptors. This demonstration of a research prototype illustrates a matching function for compound descriptors, or multi-concept subject headings, that does not rely on exact matching but incorporates term expansion via thesaurus semantic relationships to produce ranked results that take account of missing and partially matching terms. The matching function is based on a measure of semantic closeness between terms.The work is part of the EPSRC funded FACET project in collaboration with the UK National Museum of Science and Industry (NMSI) which includes the National Railway Museum. An export of NMSI's Collections Database is used as the dataset for the research. The J. Paul Getty Trust's Art and Architecture Thesaurus (AAT) is the main thesaurus in the project. The AAT is a widely used thesaurus (over 120,000 terms). Descriptors are organised in 7 facets representing separate conceptual classes of terms.The FACET application is a multi tiered architecture accessing a SQL Server database, with an OLE DB connection. The thesauri are stored as relational tables in the Server's database. However, a key component of the system is a parallel representation of the underlying semantic network as an in-memory structure of thesaurus concepts (corresponding to preferred terms). The structure models the hierarchical and associative interrelationships of thesaurus concepts via weighted poly-hierarchical links. Its primary purpose is real-time semantic expansion of query terms, achieved by a spreading activation semantic closeness algorithm. Queries with associated results are stored persistently using XML format data. A Visual Basic interface combines a thesaurus browser and an initial term search facility that takes into account equivalence relationships. Terms are dragged to a direct manipulation Query Builder which maintains the facet structure.

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Content

An diesem Punkt setzt das neue Projekt CrissCross an, das gemeinsam von der Deutschen Nationalbibliothek (DNB) und der Fachhochschule Köln betrieben und von der Deutschen Forschungsgemeinschaft (DFG) gefördert wird. CrissCross schafft Verbindungslinien zwischen einigen besonders verbreiteten und bewährten Erschließungsinstrumenten: Der deutschsprachigen Schlagwortnormdatei (SWD), den besonders im angloamerikanischen Raum verbreiteten Library of Congress Subject Headings (LCSH), der französischen Dokumentationssprache Répertoire d'autorité-matière encyclopédique et alphabétique unifié (Rameau) und der Dewey Decimal Classification (DDC) als dem international am meisten verbreiteten Klassifikationssystem. CrissCross kann dabei auf zwei wichtigen Vorgängerprojekten aufbauen. Hier ist zum einen das ebenfalls von DNB und der Fachhochschule Köln gemeinsam betriebene Vorgängerprojekt »DDC Deutsch« zu nennen. Bereits während dessen Laufzeit war deutlich geworden, wie vorteilhaft sich eine Anreicherung des DDC-Registers mit dem Schlagwortbestand der SWD auf die Klassifikationspraxis auswirken könnte. Genau dieser Schritt wird nun vollzogen, wobei sich die Projektarbeit auf die Sachschlagwörter konzentriert - kein kleines Unterfangen, beläuft sich doch die Zahl der zurzeit in der SWD befindlichen Datensätze mit dem Indikator s auf über 154.000.