This paper explores the role of information retrieval in answering "relationship" questions, a new class complex information needs formally introduced in TREC 2005. Since information retrieval is often an integral component of many question answering strategies, it is important to understand the impact of different term-based techniques. Within a framework of sentence retrieval, we examine three factors that contribute to question answering performance: the use of different retrieval engines, relevance (both at the document and sentence level), and redundancy. Results point out the limitations of purely term-based methods to this challenging task. Nevertheless, IR-based techniques provide a strong baseline on top of which more sophisticated language processing techniques can be deployed.
['Jimmy J. Lin']
The Role of Information Retrieval in Answering Complex Questions