Reformulating XQuery queries using GLAV mapping and complex unification

This paper describes an algorithm for reformulation of xquery queries. the mediation is based on an essential component called mediator. its main role is to reformulate a user query, written in terms of global schema, into queries written in terms of source schemas. our algorithm is based on the principle of logical equivalence, simple and complex unification, to obtain a better reformulation. it takes xquery query, global schema (written in xmlschema), and mappings glav as input parameters and provides resultant query written in terms of source schemas. the results of implementation show the proper functioning of the algorithm