Improving subject access painlessly: recent work on the Okapi online catalogue projects

Online catalogue research at PCL (the Polytechnic of Central London) has now been going on, mainly with British Library funding, for nearly five years. This article gives a brief survey of some of the more recent work. A detailed account of three techniques (automatic stemming (both weak and strong) of search terms, automatic cross referencing and automatic spelling corrections) that were implemented in the Okapi '86 system for improving subject retrieval effectiveness, is given. The results of evaluating Okapi '86 at PCL are also given. An appendix gives details of the search and merge algorithm used in Okapi '86.