Giorgos Serfiotis Ioanna Koffina Vassilis Christophides Val Tannen Containment and Minimization of RDF/S Query Patterns. 607-623 2005 conf/semweb/2005 International Semantic Web Conference http://dx.doi.org/10.1007/11574620_44 db/conf/semweb/iswc2005.html#SerfiotisKCT05