It uses on the original content words in q" to retrieve the top N", documents in the Web using Google and then extracts the terms in those documents that are highly correlated with the original query terms.
for Vqi" Ea it extracts the list of nearby non-trivial words, wi, where ds(wikile) gives the number of instances that wk and q/°) appear together; and ds (w,kVe ) gives the number of instances that either wfic or qi (p) appears.