Craig Boutilier Relu Patrascu Pascal Poupart Dale Schuurmans Regret-based Utility Elicitation in Constraint-based Decision Problems. 929-934 2005 conf/ijcai/2005 IJCAI http://www.ijcai.org/papers/0398.pdf db/conf/ijcai/ijcai2005.html#BoutilierPPS05