Melbourne University 2005: Enterprise and Terabyte Tasks

This report describes the work done at The University of Melbourne for the TREC2005 Enterprise and Terabyte Tracks. In the Enterprise Track, we participated in the Discussion Task. We tried a number of different methods to make use of special features of mailing lists to improve retrieval effectiveness, and found the use of thread context to be promising. In the Terabyte Track, we continued our work with impact-based ranking and sought to reduce indexing as well as query time. A new retrieval system has been developed for this purpose and has shown several improvements over our system from last year.