In order to justify the usefulness of our hierarchical learning strategy when a rough class hierarchy is not available and difficult to determine manually, we also experiment using entirely automatically built class hierarchy (using the traditional binary hierarchical clustering algorithm and the cosine similarity measurement) without considering the existing class hierarchy.
typical works include Miller et al (2000), Zelenko et al (2003), Culotta and Sorensen (2004), Bunescu and Mooney (2005a), Bunescu and Mooney (2005b), Zhang et al (2005), Roth and Yih (2002), Kambhatla (2004), Zhao and Grisman (2005) and Zhou et al (2005).