Nguyen-Thinh Le Wolfgang Menzel Using Constraint-Based Modelling to Describe the Solution Space of Ill-defined Problems in Logic Programming. 367-379 2007 ICWL http://dx.doi.org/10.1007/978-3-540-78139-4_33 conf/icwl/2007 db/conf/icwl/icwl2007.html#LeM07