Paper: Parsing Algorithms And Metrics

ACL ID P96-1024
Title Parsing Algorithms And Metrics
Venue Annual Meeting of the Association of Computational Linguistics
Session Main Conference
Year 1996

Many different metrics exist for evaluating parsing results, including Viterbi, Cross- ing Brackets Rate, Zero Crossing Brackets Rate, and several others. However, most parsing algorithms, including the Viterbi algorithm, attempt to optimize the same metric, namely the probability of getting the correct labelled tree. By choosing a parsing algorithm appropriate for the evaluation metric, better performance can be achieved. We present two new algo- rithms: the "Labelled Recall Algorithm," which maximizes the expected Labelled Recall Rate, and the "Bracketed Recall Algorithm," which maximizes the Brack- eted Recall Rate. Experimental results are given, showing that the two new al- gorithms have improved performance over the Viterbi algorithm on many criteria, es- pecially the ones that they ...