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Visualizing OPAC subject headings

Ioannis Papadakis (Department of Archive and Library Science, University of Ionio, Kerkyra, Greece)
Michalis Stefanidakis (Department of Archive and Library Science, University of Ionio, Kerkyra, Greece)
Aikaterini Tzali (Department of Archive and Library Science, University of Ionio, Kerkyra, Greece)

Library Hi Tech

ISSN: 0737-8831

Article publication date: 7 March 2008




This paper aims at providing a robust, user‐friendly and efficient navigation procedure in an online library catalog that is based on semantic information encapsulated within subject headings.


The paper describes an interactive navigation procedure inside an online library catalog based on semantic information. The proposed approach is presented through a web‐based, prototype application following the most recent trends of the semantic web such as AJAX technology and the web ontology language – OWL for encoding semantics.


According to the proposed method, a GUI interface exposes the hierarchy of the subject headings employed within an OPAC, as well as all stated relations between such headings, as links that the user can follow, effectively traversing the ontology and formulating at the same time the actual query to the underlying OPAC. This act of interactive navigation through the library's assets aids searchers in accurately formulating their queries, by offering broader or narrower concepts for selection or indicating alternative or related concepts they might be initially unaware of. The augmented exposition of inter‐relations between concepts provides multiple paths for information retrieval and enables searchers to fulfill their information needs in a faster, more efficient and intuitive manner.

Practical implications

The paper includes implications for the development of modern, semantic web applications focused on the library domain. The novel approach of visualizing subject headings could be further extended to visualize a number of other conceptualizations of the library domain.


This paper fulfils an identified need to take advantage of the “hidden knowledge” existing within the library domain but, for a number of reasons, is never exposed to the library users.



Papadakis, I., Stefanidakis, M. and Tzali, A. (2008), "Visualizing OPAC subject headings", Library Hi Tech, Vol. 26 No. 1, pp. 19-23.



Emerald Group Publishing Limited

Copyright © 2008, Emerald Group Publishing Limited

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