DUTIR at the Session Track in TREC 2011

This paper presents the DUTIR submission to TREC 2011 Session Track, the task is to test whether systems can improve their performance for a given query by using previous queries and user interactions with the retrieval system. We use language model as the basic retrieval model. Query Expansion is applied to reformulate the original query. Some other technologies like Pseudo Relevance Feedback (PRF) are also applied. The results show that our methods are effective, but the results of Query Expansion method using previous queries and user interactions are unanticipated.