[SRILM] lattice-tool LM interpolarion

[Andreas Stolcke]

In message <20061114161745.10337.qmail at web25415.mail.ukl.yahoo.com>you wrote:
> Hi,
> 
> Could anyone give me any hints on the following: when
> I interpolate different LMs (with different vocabs) to
> rescore lattices with lattice-tool (in HTK format), in
> the output lattice several links get l=-inf
> probability, that leads to the fact it is impossible
> to calculate viterbi best path etc. 
> For me it looks like the loglinear mix is performed,
> that leads to getting -inf in case at least one of the
> LMs gives this output (that is possible due to
> different vocabs). If so, is there any way to
> interpolate LMs with different vocabs in lattice-tool,
> or all the LMs should have the same vocab beforehand?
> Or I just miss something crucial in the way the whole
> thing works?
> 
> lattice-tool -in-lattice-list lat.list -read-htk
> -no-htk-nulls -htk-words-on-nodes -lm LM1 -mix-lm LM2
> -write-htk -htk-logbase 2.71828 -out-lattice-dir
> out_dir

This produces a linear (not loglinear) mixture of models.
The vocabulary of such a model is the union of the component models.

The -inf scores must be due to words that are not in the union
of the vocabularies of LM1 and LM2, or probabilities that are 
explicitly 0 in the LMs.

> 
> BTW, Andeas, thanks for the comments on accented
> characters, it works.

Glad to hear it.

Andreas