“…For example, correspondences can be used to relate one element of a given schema to one element of another schema, e.g., Sint .Staff , S1 .Employee , or to relate multiple elements of one schema to one element of another schema, e.g., the correspondence Sint .Staff , {S1 .Employee, S1 .Department} states that the relation Staff in the integration schema is semantically equivalent to some combination of the relations Employee and Department of the source schema S 1 . There are several models for drawing schematic correspondences in the literature [17,7,14,12], of which the model proposed by Kim et al [12] is perhaps the most comprehensive. In the second phase of mapping specification, the views that implement the mappings necessary for rewriting the queries issued against the integration schema into queries over the schemas of the sources are specified.…”