Harald Ganzinger Viorica Sofronie-Stokkermans Uwe Waldmann Modular Proof Systems for Partial Functions with Weak Equality. 168-182 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3097&spage=168 2004 conf/cade/2004 IJCAR db/conf/cade/ijcar2004.html#GanzingerSW04