Seokhyun Son Hyoseop Shin Zhiwei Xu Structural Semi-Join: A light-weight structural join operator for efficient XML path query pattern matching. 233-240 2007 conf/ideas/2007 IDEAS http://doi.ieeecomputersociety.org/10.1109/IDEAS.2007.43 db/conf/ideas/ideas2007.html#SonSX07