RWTH Aachen University
A schema mapping is a high-level specification that describes how data from a source schema is to be mapped to a target schema. Schema mappings are of fundamental importance in data management today. In particular, they have proved to be the essential building block for several data-interoperability tasks such as data exchange, data integration and peer data management. Most of the research on schema mappings has focused on mappings specified by the so called source-to-target tuple-generating-dependencies (st-tgds), motivated by the highly influential formalization of data exchange proposed by a researcher.