Dependency Hashing for n-best CCG Parsing

摘要

Optimising for one grammatical representation, but evaluating over a different one is a particular challenge for parsers and n-best CCG parsing. We find that this mismatch causes many n-best CCG parses to be semanti-cally equivalent, and describe a hashing technique that eliminates this problem, improving oracle n-best F-score by 0.7% and reranking accuracy by 0.4%. We also present a comprehensive analysis of errors made by the C&C CCG parser, providing the first breakdown of the impact of implementation decisions, such as supertagging, on parsing accuracy.