Worst-Case Synchronous Grammar Rules

We relate the problem of finding the best application of a Synchronous ContextFree Grammar (SCFG) rule during parsing to a Markov Random Field. This representation allows us to use the theory of expander graphs to show that the complexity of SCFG parsing of an input sentence of length N is Ω(Ncn), for a grammar with maximum rule length n and some constant c. This improves on the previous best result of Ω(Nc √ n).

• Type: Conference
• Year: 2007
• Where: NAACL
• Authors: Daniel Gildea, Daniel Stefankovic
• Keywords: Computational Linguistics, Markov Random Field, Maximum Rule Length, NAACL 2007, Synchronous ContextFree Grammar