KECIR: An Information Retrieval System for IR4QA Task

― 107 ― KECIR An Information Retrieval System for IR4QA Task Dongfeng Cai, Shengqiao Kang, Yu Bai, Peiyan Wang Knowledge Engineering Research Center, Shenyang Institute of Aeronautical Engineering [email protected] Abstract This paper describes our work on the subtask of simplified Chinese monolingual information retrieval for question answering system at ntcir-8. We use the lemur toolkit to build index in unit of Chinese word. OKAPI BM25 as retrieval model and a density-proportional based pseudo relevance feedback method were used for query expansion. To rank all documents orders, Statistical language modeling and Minimal Mean Distance (MMD) calculating method were employed. Evaluation at NTCIR-8 shows that the best T-run from our team in terms of Mean nDCG is 0.5981, 0.3411 in Mean AP and 0.3749 in Mean Q.