Five models which perform search tasks of the Data Base Access and Search Environment (DBASE) are presented and used for comparison with subject search performance--unconstrained (rule-based, decision theoretic) and constrained (optimal rule-based, rule-based, probabilistic rule-based). Previous experiments and the modeling approach are briefly…

The mathematical model proposed describes a computerized bibliographic information system which includes a method--document learning--of improving the set of index terms assigned to a document representative. Inputs to the information system (index terms and query), relevance feedback, and assumptions concerning the model are discussed.…

A statistical description of a text retrieval system allows the derivation of a unique and measurable performance criterion that, in turn, may be used in discussing various parameters of systems performance. (Author/PF)

Compares and expands upon two approaches to dealing with fuzzy relational databases. The proposed similarity measure is based on a fuzzy Hausdorff distance and estimates the mismatch between two possibility distributions using a reduction process. The consequences of the reduction process on query evaluation are studied. (Author/EM)

A new method for concentrating keywords of a thesaurus, based on a mathematical study of the distribution of characters in a defined natural language. (Author/KP)

Presents the list-structure data model for dealing with sets of objects, which has ordering as its fundamental principle. An extended notion of patterns and several operators of the algebra are presented. Design issues that influenced the development of the language are described. (Contains 30 references.) (KRN)

Presents data model based on text data model (TDM), universal relation model, and nonfirst normal form (NFNF) relations, and discusses applicability to text processing and document retrieval systems. Highlights include database technology applied to information retrieval, NFNF and universal relation, and TDM integration with NFNF universal…

The computational complexity of a formal process for the construction of term classes for information retrieval is examined. While the process is proven to be difficult computationally, heuristic methods are applied. Experimental results are obtained to illustrate the maximum possible improvement in system performance of retrieval using the formal…

Derives the underlying structure of the Zipf distribution, with emphasis on its application to word frequencies in the inverted files of automatic bibliographic systems, and applies the Zipfian model to the National Library of Medicine's MEDLINE database. An appendix on the Zipfian mean and 12 references are included. (Author/JL)

Examines how informetric characteristics of information retrieval (IR) system databases can be used to help system designers decide what type of file structures would provide the best performance. The development of appropriate models describing database contents is highlighted in this first part of a two-part study. (30 references) (LRW)

This second report on a two-part study on the application of informetrics to information retrieval (IR) system design used models of database contents in a factorial simulation study at the University of Western Ontario. The study explored whether different file structures were better suited for different informetric environments. (32 references)…