Nki Ontology Some Basic Relations

The term Ontology is derived from philosophy, and is defined as "Theory of existence". In computer science, the researchers use the basic idea of Ontology to build ontological knowledge base (for short ontologies). The ontologies are used to solve the problems in knowledge sharing. Currently, the ontologies are widely applied in the natural language process, knowledge management, information retrieval and so on.In ontological engineering, there are two types of important relations either in the ontology theory or the practical application. The first type of relation includes the is-a relation and the instance-of relation. The is-a relation links species concept to genus concept, while the instance-of relation links concept to ultimate instance of concept. The second type of relation is part-whole relation, which is used to reflect the compositional structure of the concept. In this paper, we will deeply discuss these relations in order to identify the semantic of these relations and realize the knowledge reasoning.The main research works are given in following:(1) According to the intension and extension of the concept, the is-a relation and instance-of relation are introduced;(2) According to the extension and intension of concept, the compositional structure, and partition way, the different types of part-whole relation are presented.