011), Best Paper Committee, Dublin, Ireland, 19-21 April 2011 2011 Program Committee: 3r European Conference on Information Retrieval (ECIR 2011), Workshop on Information Retrieval Over Query Sessions, Dublin, Ireland, 19-21 April 2011. 2011 Program Committee: 121" ACM Conference on Electronic Commerce (EC11). San Jose, CA. 5-9 June. 2011 Progr