Efficient Application of Answer Set Programming for Advanced Data Integration

An information integration system combines data residing at different sources, providing the user with a unified view of them, called global schema. When some constraints are imposed on the quality of the global data, the integration process becomes difficult and, in some cases, it may be unable to provide consistent results to user queries. The database community has spent many efforts in this area, relevant research results have been obtained to clarify semantics, decidability, and complexity of data-integration under constraints (often called consistent query answering - CQA). However, while efficient systems are already available for simple data integration scenarios, scalable solutions have not been implemented yet for advanced data-integration under constraints. This paper provides a contribution in this setting: it starts from state of the art techniques to carry out consistent query answering and proposes optimized solutions; these have been implemented in a efficient system based on Answer Set Programming (a purely declarative logic programming formalism). Experimental activities conducted in a real world scenario and reported in the paper confirm the effectiveness of the approach.