, thông qua liên kết các trường hợp mới đến bản thể học hiện có trong một quá trình được gọi là nền tảng bản thể học (Jakulin và Mladenic, 2005). Trong trường hợp của bản thể học chủ đề (xem Chương 7), | 52 ONTOLOGY EVOLUTION The evolution of ontologies should reflect both the changing interests of people and the changing data for example the documents stored in a digital library. In this chapter we present an overview of the state-of-the-art in ontology evolution with a special focus on change discovery for ontologies. We would like to mention that our approach supports specific steps of the DILIGENT methodology for ontology engineering described in Chapter 9. In this work we will distinguish change capturing and change discovery. The task of change capturing can be defined as the generation of ontology changes from explicit and implicit requirements. Explicit requirements are generated for example by ontology engineers who want to adapt the ontology to new requirements or by the end-users who provide explicit feedback about the usability of ontology entities. We call the changes resulting from this kind of requirements top-down changes. Implicit requirements leading to so-called bottom-up changes are reflected in the behavior of the system and can be induced by means of change discovery methods. While usage-driven changes arise out of usage patterns of the ontology data-driven changes are generated by modifications of the reference-data such as text documents or a database which contains the knowledge modeled by the ontology. The remainder of this chapter is structured as follows. In Section 2 we present an overview of the state-of-the-art in ontology evolution. In Section 3 we present a logical architecture for ontology evolution exemplified in the context of a digital library. The main components of this logical architecture are then described in detail. In Sections 4 and 5 we illustrate techniques that deal with usage-driven ontology changes and data-driven ontology changes respectively. In the former approach changes are recommended based on the actual usage of the ontologies in the latter approach we make use of the constant flows of documents coming into .
