The Ontology Problem is a fundamental challenge of the emerging Semantic Web. This problem is comprised of three key sub-problems, the Upper Ontology Problem, the Domain Ontology Problem, and the Ontology Integration Problem.
H. joon Kim. Proceedings of the First International Conference on Knowledge Science, Engineering and Management (KSEM'06), volume 4092 of Lecture Notes in Artificial Intelligence, page 202-214. Berlin, Germany, Springer, (August 2006)
J. Yeh, and S. hong Sie. Advances in Applied Artificial Intelligence, volume 4031 of Lecture Notes in Computer Science, page 982--989. Berlin / Heidelberg, Springer, (August 2006)