Abstract
Ontology is mainly used to capture “the knowledge semantics”. As knowledge is continually evolving over time, an ontology should evolve accordingly. Its previous states/versions should also be kept in order to allow the history access. Existing solutions for versions storage provide a trade-off between storage space efficiency and “knowledge semantics” keeping. Indeed, some storage strategies try to capture the evolving “knowledge semantics”, but unfortunately suffer from space overhead due to the storage of redundant information. Other strategies propose efficient storage solutions while losing the semantics of knowledge. These issues are addressed by our hybrid storage strategy which combines the benefits of the ontology and the database technologies. A reference ontology version is used to allow capturing the semantics along the whole ontology versioning process. A Temporal Object Oriented Database (TOODB) is used for storing and retrieving the ontology evolution history.