Peking University at the TREC-2005 Question and Answering Track

This paper describes the architecture and implementation of Tianwang QA system, which can work for the Main task and the Document Ranking task. The system is designed to extract candidate answer snippets from different pipelines, e.g. the high quality search engines' results, the frequently asked question (FAQ) set, and the wellstructured web facts, etc..So the system need to process the Web documents, the FAQ corpus and the knowledge base (KB) from the structural web pages, besides analyzing the query, the TREC document retrieval and the answer merging. The external knowledge we made use of, i.e. FAQ and KB, are proved to be effective for our final results. We classify questions with SVM approaches, construct queries in Boolean way, retrieve and rank the passage with span model and extract answers using named entity technologies. 1