A Form-Based Query Language Approach to NF2 Relations with Applications in Information Retrieval
Timo Niemi# and Kalervo Järvelin+
#Department of Computer Science
+Department of Information Studies
University of Tampere
P.O.Box 607
FIN-33101 TAMPERE, Finland
Information Processing & Management, 31(2), 1995, 215 - 232.
Abstract
In information retrieval (IR) there is a need for greater structural
expressiveness than that provided by ordinary retrieval systems or the
ordinary relational model. Especially hierarchical structures are usual in IR
applications. Therefore the non-first-normal-form (NF2) relational model
often is a more natural and intuitive way to model data of IR applications
than the pure relational model. Because many-to-many relationships often
exist among real world entities of IR applications it is impossible to find a
stable hierarchical structure which would be suitable to all needs of users.
This means that a tool is needed which has a powerful restructuring
capability. In other words it has to be able to produce for the user result
NF2 relations in which hierarchical relationships among data have been
organized in a way which is drastically different from that in the source
NF2 relations. In this paper we classify typical data restructuring tasks in
an IR environment and give several examples on their specifications. It has
been widely recognized that NF2 relational query formulation with
conventional query languages is too cumbersome for ordinary end users.
In order to simplify NF2 relational query formulation we have developed
and implemented a novel user interface. We show that query specification
in this interface remains compact and truly declarative - also in the context
of complex NF2 relational queries.
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