Experimental results on the cross-over point in satisfiability problems. In Proceedings of the Eleventh National Conference on Artificial Intelligence , pages 21-27, Washington, DC, USA, 1993. 6 Ian P. Gent, Ewan MacIntyre, Patrick Prosser, and Toby Walsh. Scaling effects in the CSP phase transition. 7 Ian P. Gent and Toby Walsh.
Easy problems are sometimes hard.
8 Ian P. Gent and Toby Walsh. The SAT phase transition. John Wiley and Sons, 1994. 9 Ian P. Gent and Toby Walsh. The satisfiability constraint gap.