Paper: A Synchronous Context Free Grammar for Time Normalization

ACL ID D13-1078
Title A Synchronous Context Free Grammar for Time Normalization
Venue Conference on Empirical Methods in Natural Language Processing
Session Main Conference
Year 2013
Authors

We present an approach to time normalization (e.g. the day before yesterday?2013-04-12) based on a synchronous context free grammar. Synchronous rules map the source language to formally defined operators for manipulat- ing times (FINDENCLOSED, STARTATENDOF, etc.). Time expressions are then parsed using an extended CYK+ algorithm, and converted to a normalized form by applying the opera- tors recursively. For evaluation, a small set of synchronous rules for English time expres- sions were developed. Our model outperforms HeidelTime, the best time normalization sys- tem in TempEval 2013, on four different time normalization corpora.