Extracting Synchronous Grammar Rules From Word-Level Alignments in Linear Time

We generalize Uno and Yagiura's algorithm for finding all common intervals of two permutations to the setting of two sequences with many-to-many alignment links across the two sides. We show how to maximally decompose a word-aligned sentence pair in linear time, which can be used to generate all possible phrase pairs or a Synchronous Context-Free Grammar (SCFG) with the simplest rules possible. We also use the algorithm to precisely analyze the maximum SCFG rule length needed to cover hand-aligned data from various language pairs.

• Type: Conference
• Year: 2008
• Where: COLING
• Authors: Hao Zhang, Daniel Gildea, David Chiang
• Keywords: COLING 2008, Computational Linguistics, Possible Phrase Pairs, Synchronous Context-free Grammar, Word-aligned Sentence Pair