Vincenzo Deufemia Giuseppe Polese Genoveffa Tortora Mario Vacca Conceptual Foundations of Interrogative Agents. 26-33 2007 WOA http://woa07.disi.unige.it/papers/DeufemiaConceptual.pdf conf/woa/2007 db/conf/woa/woa2007.html#DeufemiaPTV07