Discriminative models, which directly distinguish correct from incorrect hypothesis, are particularly attractive because they allow the inclusion of arbitrary features (Kuo et al., 2002;Roark et al., 2007;Collins et al., 2005); these models with syntactic information have obtained state of the art results.
both generative and discriminative LMs with long-span dependencies can be slow, for they often cannot work directly with lattices and require rescoring large N -best lists (Khudanpur and Wu, 2000;Collins et al., 2005;Kuo et al., 2009).