Steven Whang Chad Brower Jayavel Shanmugasundaram Sergei Vassilvitskii Erik Vee Ramana Yerneni Hector Garcia-Molina Indexing Boolean Expressions. 37-48 2009 2 PVLDB 1 http://www.vldb.org/pvldb/2/vldb09-83.pdf db/journals/pvldb/pvldb2.html#WhangBSVVYG09