Ronald Fagin Benny Kimelfeld Yunyao Li Sriram Raghavan Shivakumar Vaithyanathan Understanding queries in a search database system. 273-284 2010 PODS http://doi.acm.org/10.1145/1807085.1807121 conf/pods/2010 db/conf/pods/pods2010.html#FaginKLRV10