In this paper, we propose a typology of the semantic transformations for XPath queries. We focus on two main areas. The first is structural transformation for XPath query, which can be semantically contracted, expanded or complemented using structural constraints. The second is semantic qualifier transformation where the predicates, specified by [ ], in an XPath query can be eliminated or transformed. We design a set of algorithms and implement a prototype system for evaluation. We adopt two representative off-the-shelf XML data management systems to validate the effectiveness of the semantic transformations.
- Semantic transformation