In the robust track, we mainly tested our passage-based retrieval model with different passage sizes and weighting schemes. In our approach, we used two retrieval models, namely the 2-Poisson model using BM25 term weights and the vector space model (VSM) using adaptive pivoted unique document length normalization. Also, we utilize WordNet to re-weight some PRF terms and extract some context words as expanded query terms. We show that our passage-based model achieves the comparable performance on the whole query set. Moreover, our new methods of using WordNet information for query expansion can improve the retrieval performance.
D. Y. Wang, Robert Wing Pong Luk, Kam-Fai Wong