The pre-trained word embeddings obtained from a large external corpora often boost the final task performance even if they only initialize the input embedding layer. In constituency parsing, several systems also incorporate pre-trained word embeddings, such as<cite> Vinyals et al. (2015)</cite> ; Durrett and Klein (2015) . To maintain as much reproducibility of our experiments as possible, we simply applied publicly available pre-trained word embeddings, i.e., glove.840B.300d 7 , as initial values of the encoder embedding layer.