In order to jointly assign POS tags and construct a constituent structure for an input sentence, we define the following actions for the action set T , following Wang and Xue (2014): • SHIFT-X (sh-x): remove the first word from β, assign a POS tag X to the word and push it onto the top of σ; • REDUCE-UNARY-X (ru-x): pop the top subtree from σ, construct a new unary node labeled with X for the subtree, then push the new subtree back onto σ.
to achieve competitive performance, they had to combine the learned features with the traditional hand-crafted features.