Class Language Modelling

[Geetu Ambwani]

Hi, 
I am trying to use the SRILM toolkit to calculate perplexity results for
the following language model - a regular trigram model
interpolated with the class model P(w0/CW0,CW1,CW2) * P(Cw0/CW1,CW2) where
CW0,CW1 & CW2 are the equivalence classes for the predicted word and 2 the
preceding words respectively. I generated the equivalence classifications
for the words by myself and i want to know if it is possible to use the
toolkit to do the perplexity measurements if i input the class files as
data files. Can this be done at all? If any of you know how to do this, 
please reply pointing out the relevant sections of the manual i should
look up for this. 
Thanks a ton,
Geetu