Abstract: The semantic mappings between relational database and ontology arc critical to the implementation of interoperabihty between them. However, these mappings would be invalid if schema (or ontology) evolved, and it is a pre-requisite work to find the affected mappings while some change occurs. In this paper, by comparing the new version and old version of the schema (ontology) , rational evolution paths between the old version and new version were discovered,and a set of changed elements were detected. Based on the set of changed elements, we can design a query testing set,and queries in the testing set can be reformulated in virtual of corresponding mappings. Finally, if the reformulated qucries can not return a valid result set, the mappings used in reformulating queries arc proved to be invalid.

Key words: Relational database, Ontology, Semantic mapping, Mapping maintenance