A deterministic model for P2P deductive databases

This paper aims to provide a contribution to the specific topic related to the integration of information and the com-putation of queries in an open ended network of distributed peers. Each peer joining a P2P system provides or imports data from its neighbors by using a set of mapping rules, i.e. A set of semantic correspondences to a set of peers belonging to the same environment. By using mapping rules, as soon as it enters the system, a peer can participate and access all data available in its neighborhood, and through its neighborhood it becomes accessible to all the other peers. In this setting two different types of mapping rules are possible: a first type allowing to import maximal sets of atoms and a second type allowing to import minimal sets of atoms from source peers to target peers. In the proposed setting, each peer can be thought of as a resource used either to enrich (integrate) the knowledge or to fix (repair) the knowledge. The declarative semantics of a P2P system is defined in terms of preferred weak models. The specific contributions of the present paper, that extends previous works of the same au-thors, consists in extending the classical notion of consistent answer by allowing the presence of partially defined atoms, i.e. atoms with "unknown" value due to the presence of tuples in different weak models which disagree on the value of one or more attributes.