A Procedure for Mediation of Queries to Sources in Disparate Contexts

This paper discusses the algorithm we are using for the mediation of queries to disparate information sources in a Context Interchange system, where information sources may have different interpretations arising from their respective context. Queries are assumed to be formulated without regard for semantic heterogeneity, and are rewritten to corresponding mediated queries by taking into account the semantics of data codified in axioms associated with sources and receivers (the corresponding context theories). Our approach draws upon recent advances in abductive logic programming and presents an integration of techniques for query rewriting and semantic query optimization. We also demonstrate how this can be efficiently implemented using the constraint logic programming system ECLiPSe.