Anbulagan John Thornton Abdul Sattar Dynamic Variable Filtering for Hard Random 3-SAT Problems. 100-111 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2903&spage=100 2003 conf/ausai/2003 Australian Conference on Artificial Intelligence db/conf/ausai/ausai2003.html#AnbulaganTS03