Lei Chen 0003 Raghu Ramakrishnan Paul Barford Bee-Chung Chen Vinod Yegneswaran Composite Subset Measures. 403-414 2006 conf/vldb/2006 VLDB http://www.vldb.org/conf/2006/p403-chen.pdf db/conf/vldb/vldb2006.html#0003RBCY06