Andrey Balmin Fatma Ozcan Ashutosh Singh Edison Ting Grouping and Optimization of XPath Expressions in System RX. 1507-1509 2008 ICDE http://dx.doi.org/10.1109/ICDE.2008.4497605 conf/icde/2008 db/conf/icde/icde2008.html#BalminOST08