| In view of the core in knowledge-sharing and knowledge reuse, Most of the systems have used ontology as their backbone. At the beginning of building a system, the designers usually build the corresponding ontology according to the system's application demand and environment. Then, they design the system comprehensively, taking the ontology as the center. However, the real world is changing continuously, so are content, structure and the existence form of the knowledge in it. Sometimes, the meanings of some terms are also changing, and the users'requirements are changing continuously at the same time. And these changes can be not foreseen when the ontology is built. Thus, the data consistency between the static ontology and the dynamic knowledge source maybe destroyed, and the ontology can not reflect the new state of the knowledge. How to make the ontology adapt the dynamic world and make prompt adjustment according to exterior knowledge source has become important in the domain of the study for ontology.Study for ontology has become an active topic in the domain of knowledge management and artificial intelligence, which involves evolution is little. In literature [1], it thought that it important to analyze the influence produced by the specific changes at length, and it also considered the versioning problems. But it hadn't resolved the propagation of the changes in the evolution of ontology. In literature [2], it imitated the process of human learning, and proposed three patterns for the evolution of domain knowledge: design pattern, process pattern and change pattern. But this method was limited in the knowledge management, and it didn't considered the related ontologies and the propagation of changes. In literature [3], it proposed some strategies for the metadata management, including announcement mechanism, version and configuration management. Although these management thoughts could be used in the ontology evolution, because it analyzed problems at the metadata level, thus, it didn't involve the core of the ontology evolution. In view of the limitation of these methods, we produced a model for the ontology evolution to support the ontology evolution. In the systems based on ontology, after we analyzed the key problems in the ontology evolution. The goal of the model is not merely to realize the ontology evolution. It also apply the thought of the propagation of changes to evolve the related ontologies with the evolved ontology to keep the integrality and consistency of the hole system. |
