Bottom-up construction of ontologies departs from the more usual taxonomic approach to ontology development. It allows for parsimonious specification of concepts. Defined concepts are written as compact expressions that allow flexible reasoning. Obvious applications include chemistry and engineering design. For such domains, the method enables better ontologies than the taxonomic method. Taxonomic approaches remain appropriate for other applications. Bottom-up ontology construction is illustrated by presenting a drawn-out example involving an ontology of pure substances. This ontology is a simplified version of a part of the ontology developed for the Plinius project of the Knowledge-Based Systems Group, University of Twente. The viability of the approach is demonstrated by presenting a complete formalisation in pure logic programming. Chapter 1 Foreword In the Plinius project of the Knowledge-Based Systems Group at the University of Twente, ontology design is an actively pursued res...

Pre-coordination of index terms has fallen out of favor with the advent of automated information retrieval. This is unjustified, as a certain amount of pre-coordination greatly enhances the searcher's possibilities of fine-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 specified by means of an elaborate functional specification. 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. 1 Introduction 1.1 Pre- and post-coordination The advent of automated Information Retrieval (IR) systems is generally held to have implied the demise of pre-coordinated index terms. Post-coordination is the norm, said to be to the advantage of users. Briefly, the distinction between pre- a...