Generalized chart constraints for efficient PCFG and TAG parsing
Figure 2: Chart-constraint tagging accuracy.
['[ITALIC] θ', '¯¯¯¯ [ITALIC] B acc', '¯¯¯¯ [ITALIC] B prec', '¯¯¯¯ [ITALIC] B recall', '¯¯¯¯ [ITALIC] E acc', '¯¯¯¯ [ITALIC] E prec', '¯¯¯¯ [ITALIC] E recall']
We trained the chart-constraint tagger on WSJ Sections 02–21. The tagging accuracy on WSJ Section 23 is shown in Fig. As expected, an increasing threshold θ increases precision and decreases recall. Precision and recall are comparable to Roark et al. ’s log-linear model for ¯¯¯¯E. Our tagger achieves 94% recall for ¯¯¯¯B at a precision of 99%, compared to Roark et al. ’s recall of just over 80% – without the feature engineering effort required by their system.