Salvador España Vicent Estruch A Memoizing Semantics for Functional Logic Languages. 109-123 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2986&spage=109 2004 conf/esop/2004 ESOP db/conf/esop/esop2004.html#EspanaE04