Search (104 results, page 3 of 6)

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Abstract

Explores interface design raised by the development and evaluation of Okapi, a highly interactive information retrieval system based on a probabilistic retrieval model with relevance feedback. It uses terms frequency weighting functions to display retrieved items in a best match ranked order; it can also find additional items similar to those marked as relevant by the searcher. Compares the effectiveness of automatic and interactive query expansion in different user interface environments. focuses on the nature of interaction in information retrieval and the interrelationship between functional visibility, the user's cognitive loading and the balance of control between user and system

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Abstract

This paper provides an introduction to genetic algorithms, a new approach to the investigation of computationally-intensive problems that may be insoluble using conventional, deterministic approaches. A genetic algorithm takes an initial set of possible starting solutions and then iteratively improves theses solutions using operators that are analogous to those involved in Darwinian evolution. The approach is illusrated by reference to several problems in information retrieval

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Abstract

Relevance search engines, which measure the occurrence of search terms in a group of retrieved records and rank them accordingly, often produce better results than refined Boolean searches. Relevance searching has emerged from the research stage to be on the verge of becoming the standard retrieval method. Describes and evaluates the operation of DIALOG's TARGET, a major accomplishment, despite some rough edges

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Abstract

Examines and extends the logical models of information retrieval in the context of probability theory and extends the applications of these fundamental ideas to term weighting and relevance. Develops a unified framework for modelling the retrieval process with probabilistic inference to provide a common conceptual and mathematical basis for many retrieval models, such as Boolean, fuzzy sets, vector space, and conventional probabilistic models. Employs this framework to identify the underlying assumptions by each model and analyzes the inherent relationships between them. Although the treatment is primarily theoretical, practical methods for rstimating the required probabilities are provided by simple examples

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Abstract

Queries containing negation are widely recognised as presenting problems for both users and systems. In information retrieval systems such problems usually manifest themselves in the use of the NOT operator. Describes an algorithm to transform Boolean queries with negated terms into queries without negation; the transformation process is based on the use of a hierarchical thesaurus. Examines a set of user requests submitted to the Thomas Cooper Library at the University of South Carolina to determine the pattern and frequency of use of negation.

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Abstract

The subject of query formulation is analysed within the framework of adaptive linear models. The study is based on the notions of user preference and an acceptable ranking strategy. A gradient descent algorithm is used to formulate the query vector by an inductive process. Presents a critical analysis of the existing relevance feedback and probabilistic approaches.

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Abstract

Discusses online approximate information retrieval based on fuzzy mathematics. Defines fuzzy semantics. Presents an approximate fuzzy matching algorithm and an algorithm for a fuzzy word indexing agent for approximate retrieval. Also presents a case study demonstrating approximate fuzzy matching

Type

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Abstract

We survey new indices for text, with emphasis on PAT arrays (also called suffic arrays). A PAT array is an index based on a new model of text that does not use the concept of word and does not need to know the structure of text

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Abstract

Survey of several algorithms for searching a string in a text. Includes are theoretical and empirical results, as well as the actual code of each algorithm. An extensive bibliography is included

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Abstract

Presents a survey of relevance feedback techniques that have been used in past research, recommends various query modification approaches for use in different retrieval systems, and gives some guidelines for the efficient design of the relevance feedback component of a retrieval system

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Abstract

Describes the development of a retrieval system based on automatic relevance weighting of search terms and founded on the Bayesian formulation of the probability of relevance as function of term occurrence where the contribution from individual terms is assumed to be independent. The relevance pair (RP) model and the vector cosine (VC) model were compared and in the test environment improved retrieval was obtained with the RP model when compared with the VC model

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Abstract

In most commercial online systems, the retrieval system is based on the Boolean model and its inverted file organization. Since the investment in these systems is so great and changing them could be economically unfeasible, this article suggests a new ranking scheme especially adapted for hypertext environments in order to produce more effective retrieval results and yet maintain the effectiveness of the investment made to date in the Boolean model. To select the retrieved documents, the suggested ranking strategy uses multiple sources of document content evidence. The proposed scheme integrates both the information provided by the index and query terms, and the inherent relationships between documents such as bibliographic references or hypertext links. We will demonstrate that our scheme represents an integration of both subject and citation indexing, and results in a significant imporvement over classical ranking schemes uses in hybrid Boolean systems, while preserving its efficiency. Moreover, through knowing the nearest neighbor and the hypertext links which constitute additional sources of evidence, our strategy will take them into account in order to further improve retrieval effectiveness and to provide 'good' starting points for browsing in a hypertext or hypermedia environement

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Abstract

Presents a neural network approach to document semantic indexing. Reports results of a study to apply a Hopfield net algorithm to simulate human associative memory for concept exploration in the domain of computer science and engineering. The INSPEC database, consisting of 320.000 abstracts from leading periodical articles was used as the document test bed. Benchmark tests conformed that 3 parameters: maximum number of activated nodes; maximum allowable error; and maximum number of iterations; were useful in positively influencing network convergence behaviour without negatively impacting central processing unit performance. Another series of benchmark tests was performed to determine the effectiveness of various filtering techniques in reducing the negative impact of noisy input terms. Preliminary user tests conformed expectations that the Hopfield net is potentially useful as an associative memory technique to improve document recall and precision by solving discrepancies between indexer vocabularies and end user vocabularies

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Abstract

The criteria employed by end-users in making relevance judgments can be powerful and useful indicators of the values users ascribe to a variety of factors in their information seeking and use situations. This paper describes intermediate results in a long-term project intended to develop a measurement scale based on users' relevance criteria. The five tests that are reported here have involved 350 users in an effort to progressively refine and validate the scale content. The range of research questions and types of users and information environments have gradually been expanded to assess the adaptability and transferability of the instrument. The instrument provides quantitative data, notably criterion importance ratings that can be analyzed using several techniques. The substantive findings confirm those of previous studies on relevance evaluation behavior

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Abstract

Reports on a research project to evaluate and compare Boolean searching and methods of query reformulation using ranked output retrieval. Illustrates the design and operating features of the ranked output system, called ROSE (Ranked Output Search Engine), by means of typical results obtained by searching a database of 1239 records on the subject of cystic fibrosis. Concludes that further work is needed to determine the best reformulation tactics needed to harness the professional searcher's intelligence with that much more limited intelligence provided by the search software

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Abstract

Outlines a fully integrated retrieval engine that processes documents and queries at the multiple, complex linguistic levels that humans use to construe meaning. Currently undergoing beta site trials, the DR-LINK natural language text retrieval system allows searchers to state queries as fully formed, natural sentences. The meaning and matching of both queries and documents is accomplished at the conceptual level of human expression, not by the simple concurrence of keywords. Furthermore, the natural browsing behaviour of information searchers is accomodated by allowing documents identified as potentially relevant by the explicit semantics of the system to be used as relevance feedback queries which provide an appropriate implicit semantic representation of the information seeker's need

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Abstract

Proposes the weight partitioned signature file, a signature file organization for supporting document ranking. It uses multiple signature files each corresponding to one term frequency to represent terms with different term frequencies. Words with the same term frequency in a document are grouped together and hased into the signature file corresponding to that term frequency. Investigates the effect of false drops on retrieval effectiveness. Analyses the performance of the weight partitioned signature file under different search strategies and configurations. Obtains an optimal formula for storage allocation to minimise the effect of false drops on document ranks. Analytical results are supported by experiments on document collections

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Abstract

An automatic query expansion (AQE) facility in anonline catalogue was evaluated in an operational library setting. The OKAPI experimental system had other features including: ranked output 'best match' keyword searching, automatic stemming, spelling normalisation and cross referencing as well as relevance feedback. A combination of transaction log analysis, search replays, questionnaires and interviews was used for data collection. Findings show that contrary to previous results, AQE was beneficial in a substantial number of searches. Use intentions, the effectiveness of the 'best match' search and user interaction were identified as the main factors affecting the take-up of the query expansion facility

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Abstract

Compares the performance of partial match options, LEXIS/NEXIS's Freestyle, with that of traditional Boolean retrieval. Defines natural language and the natural language search engines currently available. Although the Boolean searches had better results more often than the Freestyle searches, neither mechanism demonstrated superior performance for every query. These results do not in any way prove the superiority of partial match techniques or exact match techniques, but they do suggest that different queries demand different techniques. Further study and analysis are needed to determine which elements of a query make it best suited for partial match or exact match retrieval

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Abstract

Describes an alternative method of representation for documents and queries in information retrieval systems to the 2 most common methods: free text, natural language representation and controlled language representation. The alternative method combines the advantage of both traditional approaches and overcomes the difficulties associated with each. The scheme was developed for use with Longman's Dictionary of Contemporary English and uses a computerized version of the dictionary for the automatic generation of summary level semantic representations of each document and query. The system tags each word in a document with the appropriate Subject Field Code (SFC) from the dictionary and the SFCs are summed and normalized to produce a weighted, fixed length vector of the SFC. The search system matches the query SFC vector to the document SFC vectors in the database. The documents are then ranked on the basis of their vector's similarity to the query

Type

a