Paper: Top-Down Nearly-Context-Sensitive Parsing

ACL ID D10-1066
Title Top-Down Nearly-Context-Sensitive Parsing
Venue Conference on Empirical Methods in Natural Language Processing
Session Main Conference
Year 2010

We present a new syntactic parser that works left-to-right and top down, thus maintaining a fully-connected parse tree for a few alternative parse hypotheses. All of the commonly used statistical parsers use context-free dynamic programming al- gorithms and as such work bottom up on the entire sentence. Thus they only find a complete fully connected parse at the very end. In contrast, both subjective and experimental evidence show that peo- ple understand a sentence word-to-word as they go along, or close to it. The con- straint that the parser keeps one or more fully connected syntactic trees is intended to operationalize this cognitive fact. Our parser achieves a new best result for top- down parsers of 89.4%,a 20% error reduc- tion over the previous single-parser best result for parsers...