A Technique for Information System Integration

Nowadays, a central topic in database science is the need of an integrated access to large amounts of data provided by various information sources whose contents are strictly related. Often information sources have been designed independently for autonomous applications, so they may present several kinds of heterogeneity. Particularly hard to manage is the semantic heterogeneity, which is due to schema and value inconsistencies. In this paper, we focus our attention mainly on the inconsistency which arises when conflicting instances related to the same concept and possibly coming from different sources are integrated. First, we introduce an operator, called Merge Operator, which allows us to combine data coming from different sources, preserving the information contained in each of them. Then, we present a variant of this operator, the Extended Merge Operator, which associates the integrated data with some information about the process by which they have been obtained. Finally, in order to manage conflicts among integrated data, we briefly present a technique for computing consistent answers over inconsistent databases.