Joonseon Ahn Yong Jin Kwon A Differential Fixpoint Evaluation Framework for Non-distributive Systems. 159-175 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2895&spage=159 2003 conf/aplas/2003 APLAS db/conf/aplas/aplas2003.html#AhnK03