We propose and investigate a semantics for
peer data exchange systems
(or peer data management systems) where different peers are pairwise related to each other by means of data exchange constraints and trust relationships. These two elements plus the data at the peers’ sites and the local integrity constraints for a peer are made compatible via the proposed semantics by determining a set of
, which are the intended virtual instances for the peer. The semantically correct answers from a peer to a query, called its
peer consistent answers
, are defined as those answers that are invariant under all its different solution instances. We show that solution instances can be specified as the models of logic programs with a stable model semantics.