Search (17 results, page 1 of 1)

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Abstract

In online retrieval search results do not always match the intent in spite of using correct keywords (descriptors). One of the causes of this problem is found in the hierarchical structures of the thesaurus, which often contains relations between broader and narrower concepts, the opposite of which is not necessarily true. Some examples are described from 2 thesauri, MeSH and JICST. In these cases searchers need to make an effort to increase precision

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Date

8.10.2000 11:52:22

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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.

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Abstract

This paper explores the relationships between natural language lexicons in lexical semantics and thesauri in information retrieval research. These different areas of knowledge have different restrictions on use of vocabulary; thesauri are used only in information search and retrieval contexts, whereas lexicons are mental systems and generally applicable in all domains of life. A set of vocabulary requirements that defines the more concrete characteristics of vocabulary items in the 2 contexts can be derived from this framework: lexicon items have to be learnable, complex, transparent, etc., whereas thesaurus terms must be effective, current and relevant, searchable, etc. The differences in vocabulary properties correlate with 2 other factors, the well-known dimension of Control (deliberate, social activities of building and maintaining vocabularies), and Syntagmatization, which is less known and describes vocabulary items' varying formal preparedness to exit the thesaurus/lexicon, enter into linear syntactic constructions, and, finally, acquire communicative functionality. It is proposed that there is an inverse relationship between Control and Syntagmatization.

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Date

31. 7.2006 14:22:21

Source

Cataloging and classification quarterly. 22(1996) no.1, S.77-93

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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.

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Pages

S.11-22

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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.

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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

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Abstract

In the continuing search for criteria for determining the form of compound headings (i.e., headings containing more than one word), many authors have attempted to deal with the problem of entry element and citation order. Among the proposed criteria are Cutter's concept of "significance," Kaiser's formula of "concrete/process," Prevost's "noun rule," and Farradane's categories of relationships*' (q.v.). One of the problems in applying the criteria has been the difficulty in determining what is "significant," particularly when two or more words in the heading all refer to concrete objects. In the following excerpt from Subject Catalogues: Headings and Structure, a widely cited book an the alphabetical subject catalog, E. J. Coates proposes the concept of "term significance," that is, "the word which evokes the clearest mental image," as the criterion for determining the entry element in a compound heading. Since a concrete object generally evokes a clearer mental image than an action or process, Coates' theory is in line with Kaiser's theory of "concrete/process" (q.v.) which Coates renamed "thing/action." For determining the citation order of component elements in a compound heading where the elements are equally "significant" (i.e., both or all evoking clear mental images), Coates proposes the use of "term relationship" as the determining factor. He has identified twenty different kinds of relationships among terms and set down the citation order for each. Another frequently encountered problem related to citation order is the determination of the entry element for a compound heading which contains a topic and a locality. Entering such headings uniformly under either the topic or the locality has proven to be infeasible in practice. Many headings of this type have the topic as the main heading, subdivided by the locality; others are entered under the locality as the main heading with the topic as the subdivision. No criteria or rules have been proposed that ensure consistency or predictability. In the following selection, Coates attempts to deal with this problem by ranking the "main areas of knowledge according to the extent to which they appear to be significantly conditioned by locality." The theory Coates expounded in his book was put into practice in compiling the British Technology Index for which Coates served as the editor from 1961 to 1977.

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Abstract

The second Cranfield experiment (Cranfield II) in the mid-1960s challenged assumptions held by librarians for nearly a century, namely, that the objective of providing subject access was to bring together all materials an a given topic and that the achieving of this objective required vocabulary control in the form of an index language. The results of Cranfield II were replicated by other retrieval experiments quick to follow its lead and increasing support was given to the opinion that natural language information systems could perform at least as effectively, and certainly more economically, than those employing index languages. When the results of empirical research dramatically counter conventional wisdom, an obvious course is to question the validity of the research and, in the case of retrieval experiments, this eventually happened. Retrieval experiments were criticized for their artificiality, their unrepresentative sampies, and their problematic definitions-particularly the definition of relevance. In the minds of some, at least, the relative merits of natural languages vs. indexing languages continued to be an unresolved issue. As with many eitherlor options, a seemingly safe course to follow is to opt for "both," and indeed there seems to be an increasing amount of counsel advising a combination of natural language and index language search capabilities. One strong voice offering such counsel is that of Robert Fugmann, a chemist by training, a theoretician by predilection, and, currently, a practicing information scientist at Hoechst AG, Frankfurt/Main. This selection from his writings sheds light an the capabilities and limitations of both kinds of indexing. Its special significance lies in the fact that its arguments are based not an empirical but an rational grounds. Fugmann's major argument starts from the observation that in natural language there are essentially two different kinds of concepts: 1) individual concepts, repre sented by names of individual things (e.g., the name of the town Augsburg), and 2) general concepts represented by names of classes of things (e.g., pesticides). Individual concepts can be represented in language simply and succinctly, often by a single string of alphanumeric characters; general concepts, an the other hand, can be expressed in a multiplicity of ways. The word pesticides refers to the concept of pesticides, but also referring to this concept are numerous circumlocutions, such as "Substance X was effective against pests." Because natural language is capable of infinite variety, we cannot predict a priori the manifold ways a general concept, like pesticides, will be represented by any given author. It is this lack of predictability that limits natural language retrieval and causes poor precision and recall. Thus, the essential and defining characteristic of an index language ls that it is a tool for representational predictability.

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Date

1. 8.1996 22:01:00

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Date

22. 9.2007 15:45:57

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Source

Wissensspeicher in digitalen Räumen: Nachhaltigkeit - Verfügbarkeit - semantische Interoperabilität. Proceedings der 11. Tagung der Deutschen Sektion der Internationalen Gesellschaft für Wissensorganisation, Konstanz, 20. bis 22. Februar 2008. Hrsg.: J. Sieglerschmidt u. H.P.Ohly

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Date

1. 8.1996 22:01:00

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Date

22. 1.2021 14:24:32

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Footnote

Original in: Information retrieval today: papers presented at an Institute conducted by the Library School and the Center for Continuation Study, University of Minnesota, Sept. 19-22, 1962. Ed. by Wesley Simonton. Minneapolis, Minn.: The Center, 1963. S.21-36.