Dipartimento di Ingegneria informatica, automatica e gestionale

We study the problem of designing reverse engineering techniques for associating semantic descriptions to existing data services. We base our proposal on the Ontology-Based Data Access paradigm, where a domain ontology is used to provide a semantic layer mapped to the data sources of an organization. The basic idea is to perform the reverse engineering of a data service, expressed a query over the data sources, by deriving a query over the ontology that explains the semantics of the data service in terms of the element of the ontology. We illustrate a formal framework for this problem, based on the notion of source-to-ontology rewriting, which comes in three variants, called sound, complete and perfect, respectively. We present a thorough complexity analysis of two computational problems, namely verification (checking whether a query is a source-to-ontology rewriting of a given data service), and computation (computing a source-to-ontology rewriting of a data service).