Abstracts Chosen from Recent Issues of Journals in the Retrieval Area

(Chosen by G. Salton from recent issues of journals in the retrieval area.) AN EXTENDED RELATIONAL DOCUMENT RETRIEVAL MODEL David C. Blair, Associate Professor, Computer and Information Systems, The University of Michigan, Ann Arbor, MI 48109, USA. Relational Data Base Management Systems offer a commercially available tool with which to build effective document retrieval systems. The full potential of the relational model for supporting the kind of ad hoc inquiry characteristics of document retrieval has only recently been explored. In addition, commercially available relational DBMS's also provide effective tools for managing document data bases by providing facilities for, inter alia, concurrency control, data migration and reorganization routines, authorization mechanisms, enforcement of integrity constraints, dynamic data definition, etc. This article will present a relational logical model to support a sophisticated document retrieval system in which flexible forms of inferential and associative searching can be performed. Examples of ad hoc inquiry will be presented in SQL. Several problems of particular importance to document retrieval will be discussed, including the importance of Conjunctive Normal Form in query formulation, unique aspects of document retrieval storage and processing overhead, and techniques for reducing the size of storage without severely impacting impacting retrieval effectiveness. (INFORMATION PROCESSING & MANAGEMENT, Vol. 24, No. 3, pp. 349-371, 1988) THE NECESSITY FOR ADAPTATION IN MODIFIED BOOLEAN DOCUMENT RETRIEVAL SYSTEMS Michael D. Gordon, Computer and Information Systems, Graduate School of Business Administration, University of Michigan, Ann Arbor, M148108, USA. A document retrieval system may be described by three formal characteristics: the syntax employed to describe documents (keywords or vectors of weights, for instance), the form of machine-processable queries it accepts as valid (unordered sets of keywords, keywords with Boolean connectives or weighted vectors, for example), and the retrieval rules used to rank or retrieve documents. This article argues that the interdependence among document descriptions, queries, and retrieval rules requires adaptation for the system to perform effectively when one of its components changes. Recently, suggestions have been made to modify traditional Boolean document retrieval systems to allow more flexible queries and ranked document output. However, these new forms of queries and retrieval rules likely require that documents be described differently than they are in existing, commercial Boolean retrieval systems. A "genetic algorithm" is discussed as a means for redescribing documents. This probabilistic algorithm uses feedback along with alternative descriptions of a single document and takes accounts of the dependency slructure of subject terms. (INFORMATION PROCESSING & MANAGEMENT, Vol. 24, Nov. 3, pp. 339-347, 1988) ESTIMATING EFFECTIVE DISPLAY SIZE IN ONLINE RETRIEVAL SYSTEMS Danny P. Wallace, School of Library and Information Science, Indiana University, Bloomington, IN 47405, USA.