(Zelenko et al., 2002;Culotta and Sorensen, 2004;Culotta and Sorensen, 2004;Bunescu and Mooney, 2005;Zhang et al., 2005;Bunescu, 2007;Nguyen et al., 2009;Zhang et al., 2006).
such approaches can be applied to few relation types thus distant supervised learning (Mintz et al., 2009) was introduced to tackle such problem.