11. A computer program product for schema integration, the computer program product including a non-transitory computer readable medium storing instructions for causing a computer to implement a method, the method comprising: recasting a first source schema into a first graph of concepts with HasA relationships; recasting a second source schema into a second graph of concepts with HasA relationships; identifying matching concepts in the first graph and the second graph based on correspondences between attributes of the concepts of the first and second graphs; enumerating the first graph of concepts and the second graph of concepts to output a plurality of integrated schemas that consider choices of concepts that merge and concepts that do not merge; applying enumeration constraints to determine how the concepts merge; producing an integrated schema from the plurality of integrated schemas, based on a fixed specification of matching concepts to merge; and generating a mapping from the first source schema to the integrated schema and from the second source schema to the integrated schema.
11. A computer program product for schema integration, the computer program product including a non-transitory computer readable medium storing instructions for causing a computer to implement a method, the method comprising: recasting a first source schema into a first graph of concepts with HasA relationships; recasting a second source schema into a second graph of concepts with HasA relationships; identifying matching concepts in the first graph and the second graph based on correspondences between attributes of the concepts of the first and second graphs; enumerating the first graph of concepts and the second graph of concepts to output a plurality of integrated schemas that consider choices of concepts that merge and concepts that do not merge; applying enumeration constraints to determine how the concepts merge; producing an integrated schema from the plurality of integrated schemas, based on a fixed specification of matching concepts to merge; and generating a mapping from the first source schema to the integrated schema and from the second source schema to the integrated schema. 15. The computer program product as claimed in claim 11 wherein the integrated schema preserves all attributes and relationships of the first source schema and the second source schema.