Search (7 results, page 1 of 1)

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Abstract

A thesaurus in the controlled vocabulary environment is a tool designed to support effective infonnation retrieval (IR) by guiding indexers and searchers consistently to choose the same terms for expressing a given concept or combination of concepts. Terms in the thesaurus are linked by relationships of three well-known types: equivalence, hierarchical, and associative. The functions and properties of these three basic types and some subcategories are described, as well as some additional relationship types conunonly found in thesauri. Progressive automation of IR processes and the capability for simultaneous searching of vast networked resources are creating some pressures for change in the categorization and consistency of relationships.

Date

22. 9.2007 15:45:57

Type

a

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Abstract

The basic elements of faceted thesauri are described, together with a review of their origins and some prominent examples. Their use in browsing and searching applications is discussed. Faceted thesauri are distinguished from faceted classification schemes, while acknowledging the close similarities. The paper concludes by comparing faceted thesauri and related knowledge organization systems to ontologies and discussing appropriate areas of use.

Content

Beitrag eines Themenheftes "Facets: a fruitful notion in many domains".

Type

a

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Abstract

The current standards for monolingual and multilingual thesauri are long overdue for an update. This applies to the international standards ISO 2788 and ISO 5964, as well as the corresponding national standards in several countries and the American standard ANSI/NISO Z39.19. Work is now under way in the UK and in the USA to revise and extend the standards, with particular emphasis on interoperability needs in our world of vast electronic networks. Work in the UK is starting with the British Standards, in the hope of leading on to one international standard to serve all. Some of the issues still under discussion include the treatment of facet analysis, coverage of additional types of controlled vocabulary such as classification schemes, taxonomies and ontologies, and mapping from one vocabulary to another. 1. Are thesaurus standards still needed? Since the 1960s, even before the renowned Cranfield experiments (Cleverdon et al., 1966; Cleverdon, 1967) arguments have raged over the usefulness or otherwise of controlled vocabularies. The case has never been proved definitively one way or the other. At the same time, a recognition has become widespread that no one search method can answer all retrieval requirements. In today's environment of very large networks of resources, the skilled information professional uses a range of techniques. Among these, controlled vocabularies are valued alongside others. The first international standard for monolingual thesauri was issued in 1974. In those days, the main application was for postcoordinate indexing and retrieval from document collections or bibliographic databases. For many information professionals the only practicable alternative to a thesaurus was a classification scheme. And so the thesaurus developed a strong following. After computer systems with full text search capability became widely available, however, the arguments against controlled vocabularies gained more followers. The cost of building and maintaining a thesaurus or a classification scheme was a strong disincentive. Today's databases are typically immense compared with those three decades ago. Full text searching is taken for granted, not just in discrete databases but across all the resources in an intranet or even the Internet. But intranets have brought particular frustration as users discover that despite all the computer power, they cannot find items which they know to be present an the network. So the trend against controlled vocabularies is now being reversed, as many information professionals are turning to them for help. Standards to guide them are still in demand.

Type

a

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Abstract

A thesaurus is a controlled vocabulary designed to allow for effective information retrieval. It con- sists of different kinds of semantic relationships, with the aim of guiding users to the choice of the most suitable index and search terms for expressing a certain concept. The relational semantics of a thesaurus deal with methods to connect terms with related meanings and arc intended to enhance information recall capabilities. In this paper, focused on hierarchical relations, different aspects of the relational semantics of thesauri, and among them the possibility of developing richer structures, are analyzed. Thesauri are viewed as semantic tools providing, for operational purposes, the representation of the meaning of the terms. The paper stresses how theories of semantics, holding different perspectives about the nature of meaning and how it is represented, affect the design of the relational semantics of thesauri. The need for tools capable of representing the complexity of knowledge and of the semantics of terms as it occurs in the literature of their respective subject fields is advocated. It is underlined how this would contribute to improving the retrieval of information. To achieve this goal, even though in a preliminary manner, we explore the possibility of setting against the framework of thesaurus design the notions of language games and hermeneutic horizon.

Type

a

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Abstract

This paper discusses issues concerning the augmentation of thesaurus relationships, in light of new application possibilities for retrieval. We first discuss a case study that explored the retrieval potential of an augmented set of thesaurus relationships by specialising standard relationships into richer subtypes, in particular hierarchical geographical containment and the associative relationship. We then locate this work in a broader context by reviewing various attempts to build taxonomies of thesaurus relationships, and conclude by discussing the feasibility of hierarchically augmenting the core set of thesaurus relationships, particularly the associative relationship. We discuss the possibility of enriching the specification and semantics of Related Term (RT relationships), while maintaining compatibility with traditional thesauri via a limited hierarchical extension of the associative (and hierarchical) relationships. This would be facilitated by distinguishing the type of term from the (sub)type of relationship and explicitly specifying semantic categories for terms following a faceted approach. We first illustrate how hierarchical spatial relationships can be used to provide more flexible retrieval for queries incorporating place names in applications employing online gazetteers and geographical thesauri. We then employ a set of experimental scenarios to investigate key issues affecting use of the associative (RT) thesaurus relationships in semantic distance measures. Previous work has noted the potential of RTs in thesaurus search aids but also the problem of uncontrolled expansion of query term sets. Results presented in this paper suggest the potential for taking account of the hierarchical context of an RT link and specialisations of the RT relationship

Type

a

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Abstract

In this paper the possibility to develop a richer relational structure for thesauri is explored and described. The development of a new environmental thesaurus - EARTh (Environmental Applications Reference Thesaurus) - is serving as a case study for exploring the refinement of thesaurus relational structure by specialising standard relationships into different subtypes. Together with benefits and opportunities, implications and possible challenges that an expanded set of thesaurus relations may cause are evaluated.

Type

a

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Abstract

Relationships between the terms in thesauri and Indexes are the subject of national and international standards. The standards for thesauri enumerate and provide criteria for three basic types of relationship: equivalence, hierarchical, and associative. Standards and guidelines for indexes draw an the thesaurus standards to provide less detailed guidance for showing relationships between the terms used in an Index. The international standard for multilingual thesauri adds recommendations for assuring equal treatment of the languages of a thesaurus. The present standards were developed when lookup and search were essentially manual, and the value of the kinds of relationships has never been determined. It is not clear whether users understand or can use the distinctions between kinds of relationships. On the other hand, sophisticated text analysis systems may be able both to assist with development of more powerful term relationship schemes and to use the relationships to improve retrieval.

Type

a