With the availability of large-scale annotated corpora such as Penn Treebank (Marcus et al., 1993), it is easy to train a high-performance dependency parser using supervised learning methods.
current state-of-the-art statistical dependency parsers (McDonald et al., 2005;McDonald and Pereira, 2006;Hall et al., 2006) tend to have lower accuracies for longer dependencies (McDonald and Nivre, 2007).