New functionalities of OPACs and relevance ranking

Abstract

This paper aims to contribute to the debate on OPAC enhancement, and in particular it concerns the use of ranking queries results considering the supposed relevance for users, mainly based on the terms frequency and inverse document frequency (TF/IDF), until now used by search engines and on line bookstores, and recently applied to OPAC. Some notable example of new generation OPAC (NCSU Libraries, LIBRIS, AQUABROWSER Library Platform) are described.
The critical examination of the use of relevance ranking gives the opportunity to analyse the concepts of relevance and pertinence from a theoretical point of view. Pertinence perspective, in particular, that considers the level of knowledge of users, offers the chance to enhance semantic search functions in OPAC, following indexing strategies which allow to put in evidence topic variety and different levels of topic examination.