Stephen J. Hegner The Relative Complexity of Updates for a Class of Database Views. 155-175 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2942&spage=155 2004 conf/foiks/2004 FoIKS db/conf/foiks/foiks2004.html#Hegner04