We participated in two multi-document summarization tasks (Task 2 and Task 5) at the DUC-2004 formal run and evaluated the performance of our summarization system. Our system based on sentence extraction also uses a module to estimate similarity between sentences. The similarity information was used for either selecting the representative sentence among similar sentences or gathering key sentences that have similar structures but different contents. We also incorporated a module which categorized document sets into two groups corresponding to the distribution of key sentences.
