Semantic query formulation and evaluation for XML databases

A semantic query attempts to help a user obtain or manipulate data in a database without knowing its detailed syntactic structure. Formulation and evaluation of semantic queries require schematic and other constraint information as well as general domain knowledge. A new approach to the formulation and evaluation of semantic queries for XML databases is proposed. It employs XML Declarative Description (XDD) - XML based knowledge representation - to model the databases together with the schemata of their XML elements and to represent domain knowledge resulting in a uniform representation of all the required information. Equivalent transformation (ET) - a new computation paradigm which transforms a representation into another while preserving their meanings - is used to optimize and evaluate the queries.