Many NLP researchers have attempted to automatically acquire hyponymy relations from texts (Hearst, 1992; Caraballo, 1999; Mann, 2002; Fleischman et al., 2003; Morin and Jacquemin, 2004; Shinzato and Torisawa, 2004; Etzioni et al., 2005; Pantel and Pennacchiotti, 2006; Sumida et al., 2006;<cite> Sumida and Torisawa, 2008)</cite> .