Silvio do Lago Pereira Leliane Nunes de Barros High-Level Robot Programming: An Abductive Approach Using Event Calculus. 73-82 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3171&spage=73 2004 conf/sbia/2004 SBIA db/conf/sbia/sbia2004.html#PereiraB04a