Gregory J. Duck Peter J. Stuckey Maria J. García de la Banda Christian Holzbaur The Refined Operational Semantics of Constraint Handling Rules. 90-104 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3132&spage=90 2004 conf/iclp/2004 ICLP db/conf/iclp/iclp2004.html#DuckSBH04