Stack-Pointer Networks for Dependency Parsing
Table 2: Parsing performance on the test data of PTB with different versions of POS tags.
['[BOLD] POS', 'UAS', 'LAS', 'UCM', 'LCM']
The parser with gold-standard POS tags significantly outperforms the other two parsers, showing that dependency parsers can still benefit from accurate POS information. The parser with predicted (imperfect) POS tags, however, performs even slightly worse than the parser without using POS tags. It illustrates that an end-to-end parser that doesn’t rely on POS information can obtain competitive (or even better) performance than parsers using imperfect predicted POS tags, even if the POS tagger is relative high accuracy (accuracy > 97% in this experiment on PTB).