Yung-Chih Chen Chun-Yao Wang Enhancing SAT-based sequential depth computation by pruning search space. 397-400 2009 ACM Great Lakes Symposium on VLSI http://doi.acm.org/10.1145/1531542.1531632 conf/glvlsi/2009 db/conf/glvlsi/glvlsi2009.html#ChenW09