Modal query language for databases with partial orders

Abstract

The data integration of a number of local heterogeneous databases, with possible conflicting, mutually inconsistent, information, coming from different places, is an increasingly important issue. In order to avoid such inconsistency, a number of current in-practice developed database systems are based on different software and architectural paradigms, and are specified a number of embedded ad-hocalgorithms for a kind of preferred query-answering w.r.t. some preordering. The query-answering to conjunctive queries is usually performed in two consecutive steps: first are obtained certain answers from the underlying DBMS system, and successively is applied a filtering software, based on particular user-written algorithms, in order to obtain a 'best subset' of answers. Thus, the obtained resulting answers does not correspond to the original user's query: to which kind of logic formula the obtained answers correspond was an open problem. In this paper we show that such bivalent database/software-algorithm paradigm can be unified in an equivalent Object Type (AOT) database with a partial order, and that the query formula which returns with the same answers, as the answers to a conjunctive query of the original database/software-algorithm, is a modal logic formula. © Springer-Verlag 2004.