We also added our original features and their combinations, with reference to (Sassano, 2004;Kudo and Matsumoto, 2002), but we removed the features that had a frequency of less than 30 in our training data.
we think correct probability estimation using an occurrence ordered set is difficult, because it gives rise to an explosion in the number of combination, The evaluation data we used was Kyodai Corpus 3.0, a corpus manually annotated with dependency relations (Kurohashi and Nagao, 1998a).