mentary nodes that capture the focus of keyword que-
ries, besides the content nodes. More importantly, each
self-integral tree represents an integrated meaning to
answer a keyword query. The retrieval of meaningful
self-integral trees (MSI-Trees) is accelerated by using
the B+
-tree index and a bloom filter to improve the
efficiency. The MSI-Trees are then ranked to return
top-k results. To the best of our knowledge, this is the
first paper to identify MSI-Trees with complementary
nodes as the results of keyword searches in XML
documents.