Global S chema G eneration U sing Formal Ontologies

This paper deals with the problem of handling semantic heterogeneity during schema integration. Semantics refer to the meaning of data in contrast to syntax, which solely defines the structure of schema elements. We focus on the part of semantics related to the meanings of terms used to name schema elements. Our approach does not rely on the names of the schema elements or the structure of the schema. Instead, we present an approach based on formal ontologies pre- sented in a logical language for integrating schemas to generate a global schema. Semantic similarity relations between definitions in formal ontologies are de- fined and used for merging ontologies. We show how similarity relations are dis- covered by a reasoning system using a higher-level ontology. The result of the merging process is used for schema integration. Schema integration is used to ob- tain the global schema of a tightly-coupled federated database system. After- wards, we illustrate how the produced global schema can help for the mapping of data elements.