Mario Köppen, Kaori Yoshida, Kei Ohnishi. A GRATIS theorem for relational optimization. In Ajith Abraham, Mohamed Kamel, Ronald R. Yager, editors, 11th International Conference on Hybrid Intelligent Systems, HIS 2011, Melacca, Malaysia, December 5-8, 2011. pages 674-679, IEEE, 2011. [doi]
Abstract is missing.