class-SLM

[Hongqin Liu]

Hi,

I am trying to construct a class based trigram LM. The function
"ngram-class" only induces classes for a bigram model. I have my own
class definitions with the class-format. When I use these definition
with the "ngram" function (-classes option), the LM leads to a higher
perplexity and word error rate than those from a word based trigram. Is
there any other approach with which I can get a class-based LM with
lower perplexity the a word-based?

By the way, anyone tried a 4gram model with pfsg format?

Thanks!

Hongqin Liu