Bottom-up extraction and maintenance of ontology-based metadata

In this chapter, several flexible techniques aimed at extracting, maintaining and enriching semantic-web style metadata are discussed. Such techniques were designed for being applied in the framework of dynamic Communities of Practice (CoP) interactions. Namely, we present a way of building ontologies that proceeds in a bottom-up fashion, defining concepts as clusters of concrete objects. Unlike huge, "supply-side" normative ontologies, our bottom-up ontologies are based on use of implicit and, therefore, parsimonious part-whole and is-a relations. This makes them suitable for the ad-hoc style of conceptualization used within communities of practice and peer-to-peer (P2P) communities. Also we discuss how metadata based on bottom-up ontologies can be associated with a flexible degree of trust by collecting user feedback. Our bottom-up extraction method complements current practice, where, as a rule, ontologies are built top-down. It is not claimed that bottom-up construction is a generally valid recipe; rather, the approach is intended to enrich the ontology developer's palette when designing and implementing Semantic Web applications.