Kalev Kask Rina Dechter Vibhav Gogate Counting-Based Look-Ahead Schemes for Constraint Satisfaction. 317-331 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3258&spage=317 2004 conf/cp/2004 CP db/conf/cp/cp2004.html#KaskDG04