Ola Angelsmark Peter Jonsson Improved Algorithms for Counting Solutions in Constraint Satisfaction Problems. 81-95 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2833&spage=81 2003 conf/cp/2003 CP db/conf/cp/cp2003.html#AngelsmarkJ03