Fusion and clustering are two approaches to improving the effectiveness of
information retrieval. In fusion, ranked lists are combined together by various means. The motivation is that different IR systems will complement each other, because they usually emphasize different query features when determining relevance and retrieve different sets of documents. In clustering, documents are clustered either before or after retrieval. The motivation is that similar documents tend to be relevant to the same query so that this approach is likely to retrieve more relevant documents by identifying clusters of similar documents. In this
paper, we present a novel fusion technique that can be combined with clustering to achieve consistent improvements over conventional approaches. Our method involves three steps: (1) clustering similar documents, (2) re-ranking retrieval results, and (3) combining retrieval results.