Coordination Recovered

Pre-coordination of index terms has fallen out of favor with the advent of automated information retrieval. This is unjustiied, as a certain amount of pre-coordination greatly enhances the searcher's possibilities of ne-tuning the query to match the level of detail of the information request. We propose a system of index concepts that allows concepts to be coordinated by means of special coordinators. The query engine able to handle coordinated and uncoordinated concepts is speciied by means of an elaborate functional speciication. The query engine combines the facilities of pre-and post-coordination. The feasibility of the query engine is demonstrated by a prototype that can be run over WWW.