Matthias M. Hölzl Max Meier Martin Wirsing Which Soft Constraints do you Prefer? 189-205 2009 238 Electr. Notes Theor. Comput. Sci. 3 http://dx.doi.org/10.1016/j.entcs.2009.05.020 db/journals/entcs/entcs238.html#HolzlMW09