Marco Valtorta, M. Ishaq Zahid. Some heuristics cannot be derived from relaxed models (abstract only). In C. Jinshong Hwang, Richard S. Brice, editors, Proceedings of the 19th annual conference on Computer Science, CSC '91, San Antonio, Texas, USA, March 4-7, 1991. pages 698, ACM, 1991. [doi]
Abstract is missing.