Study On Ontology-based Knowledge Organization

Ontology originated in philosophy. Aristotle defined "Ontology" as science about"being" in the world. Since 1990s, ontology has been introduced in Artificial Intelligence, Knowledge Engineering and Library&Information sciences. And then the definition of ontology has been changed. Ontology learning includes the research on knowledge representation and knowledge organization in the domains mentioned above. In Library&Information science, ontology is a vocabulary with the specification of relationships between terms about a special domain. Ontology learning and practicing have been developing rapidly these years. The theory and technology of ontology get rnaturer than before. The applying of ontology gets more extensive than before. The research level of ontology in China is not as developed as the western countries now. There is still no domain-oriented tentative or demo system based on ontology in Library&Information fields in China.The importance of constructing domain ontology is:First, the aim of constructing domain ontology is to acquire knowledge of thisdomain, and to define the admissive concepts and the relationship of these concepts at different level in a formalized mode. As a result, a criterion of understanding knowledge is developed. So, domain ontology offers a top-level concept framework of people's cognition.Second, ontology emphasizes the function of knowledge sharing. Although both of the thesaurus and ontology expresses the relationship of the domain concepts, the ontology stresses on providing a framework of the domain knowledge. Because the concept of ontology has its own attributes and instances which are not demonstrated in the thesaurus, the ontology are usually called a collection of domain knowledge. Third, ontology provides a machine language, which can be understood by computer. We can get over the problem of semantic gap from different kinds of computer systems. As a result, the conversation, mutual-operation and knowledge sharing of different entity can be realized. The ontology is considered as an explicit specification of the formalized conceptualization. The formal means the ontology can be read by the computers.