Lexicalization can increase parsing performance dramatically for English (Carroll and Rooth, 1998;Charniak, 1997Charniak, , 2000Collins, 1997), and the lexicalized model proposed by Collins (1997) has been successfully applied to Czech (Collins et al., 1999) and Chinese (Bikel and Chiang, 2000).
lexicalization has been shown to improve parsing performance for the Penn Treebank (e.g., Carroll and Rooth 1998;Charniak 1997Charniak , 2000Collins 1997).