Piero A. Bonatti Juri Luca De Coi Daniel Olmedilla Luigi Sauro Policy-Driven Negotiations and Explanations: Exploiting Logic-Programming for Trust Management, Privacy & Security. 779-784 2008 ICLP http://dx.doi.org/10.1007/978-3-540-89982-2_76 conf/iclp/2008 db/conf/iclp/iclp2008.html#BonattiCOS08