Our interpretation of this is that it provides an indication of what the parser is providing on top of the gold dependency structure, which is roughly the same information that we have encoded in our DS to PS code.
because the Wang and Zong (2010) system performs better than our USE-POS version, it is likely learning some of the nonstraightforward cases of how USE-POS tags can bootstrap the syntactic structure that our USE-POS version is missing.