For the experiments reported in this paper, we have used the software package TiMBL (Tilburg Memory Based Learner), which provides a variety of metrics, algorithms, and extra functions on top of the classical k nearest neighbor classification kernel, such as value distance metrics and distance weighted class voting (Daelemans et al., 2003).
the Penn Treebank of American English (Marcus et al., 1993) has been used to train and evaluate the best available parsers of unrestricted English text (Collins, 1999;Charniak, 2000).