Antonio Bucciarelli Benjamin Leperchey Hypergraphs and Degrees of Parallelism: A Completeness Result. 58-71 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2987&spage=58 2004 conf/fossacs/2004 FoSSaCS db/conf/fossacs/fossacs2004.html#BucciarelliL04