[1] F. Calimeri, S. Cozza, G. Ianni, "External Sources of Knowledge and Value Invention in Logic Programming", Annals of Mathematics and Artificial Intelligence, 2007, to appear. PDF
[2] F. Calimeri, S. Cozza, G. Ianni, "Decidable fragments of Logic Programming with Value Invention", Proceedings of the 10th European Conference on Logics in Artificial Intelligence (JELIA'06) in Logics in Artificial Intelligence, Lecture Notes in Computer Science (LNCS), v. 4160, pp. 95-110, September 2006, Liverpool, UK, Springer Verlag, GmbH Tiergartenstrasse 17, 69121, Heidelberg Germany, ISBN 3-540-39625-X. PDF
[3] F. Calimeri, G. Ianni, "External sources of computation for Answer Set Solvers", Proceedings of the 8th International Conference on Logic Programming and Nonmonotonic Reasoning (LPNMR'05), Diamante, Italy, 5-8 September 2005, Springer Verlag. PDF