Immediate-Head Parsing for Language Models
We present two language models based upon an ``immediate-head'' parser
-- our name for a parser that conditions all events below a
constituent c upon the head of c. While all of the most accurate
statistical parsers are of the immediate-head variety, no previous
grammatical language model uses this technology. The perplexity for
both of these models significantly improve upon the trigram model
base-line as well as the best previous grammar based language model.
For the better of our two models these improvements are 24% and 13%
respectively. We also suggest that improvement of the underlying
parser should significantly improve the model`s perplexity and that
even in the near term there is a lot of room for improvement in
immediate-head language models.