Improved Parsing for Argument-Clusters Coordination
Table 3: The parser Recall score in recovering ACC conjunct spans on the Regents dataset. ACCPTB: the set is annotated with the verb inside the first cluster. ACCOUR: the set is annotated following our approach.
['[EMPTY]', '[BOLD] PTB Trees', '[BOLD] Modified Trees']
When evaluating the PTB-trained parser on ACCPTB, it correctly recovers only 13% of the ACC boundaries. Somewhat surprisingly, the PTB-trained parser performs better when evaluated against ACCOUR, correctly recovering 24.1% of the structures. This highlights how unnatural the original ACC representation is for the parser: it predicts the alternative representation more often than it predicts the one it was trained on. When the parser is trained on the modified trees, results on ACCOUR jump to 64.8%, correctly recovering ×2.7 more structures.