  This paper discusses the use of Wikipedia for building semantic ontologies to
do Query Expansion (QE) in order to improve the search results of search
engines. In this technique, selecting related Wikipedia concepts becomes
important. We propose the use of network properties (degree, closeness, and
pageRank) to build an ontology graph of user query concepts which is derived
directly from Wikipedia structures. The resulting expansion system is called
Wiki-MetaSemantik. We tested this system against other online thesauruses and
ontology based QE in both individual and meta-search engines setups. Despite
that our system has to build a Wikipedia ontology graph in order to do its
work, the technique turns out to work very fast (1:281) compared to another
ontology QE baseline (Wikipedia Persian ontology QE). It has thus the potential
to be utilized online. Furthermore, it shows significant improvement in
accuracy. Wiki-MetaSemantik also shows better performance in a meta-search
engine (MSE) set up rather than in an individual search engine set up.
