Long Short-Term Memory Over Tree Structures
Table 3: Performances of models that do not use the given sentence structures. S-LSTM-LR is a degenerated version of S-LSTM that reads input words from left to right, and S-LSTM-RR reads words from right to left.
['Models', 'roots']
In the case of using only root labels, the left recursive S-LSTM and right recursive S-LSTM have similar performance (40.2 and 40.3, respectively), both inferior to S-LSTM (43.5). When using gold leaf labels, the gaps are smaller, but still, using the parse structure are better. Note that in real applications, where there is no out-of-vocabulary issue (i.e., some leafs are not seen in the sentiment dictionaries), the difference between S-LSTM and the recursive version without using the structures are expected to be between the gaps we observed here.