Tuan A. Nguyen Minh Binh Do Subbarao Kambhampati Biplav Srivastava Planning with Partial Preference Models. 1772-1777 2009 IJCAI http://ijcai.org/papers09/Papers/IJCAI09-295.pdf conf/ijcai/2009 db/conf/ijcai/ijcai2009.html#NguyenDKS09