compute-best-mix

[Anand Venkataraman]

Hongqin

> It seems that it's working, but very slow, my corpus is 265K sentences,
> not too big.

17+ hours indicates that something unusual going on.  Is the process
swapping heavily on a slow machine?  We have tuned parameters on much
larger corpora in shorter times.

If you are having real efficiency problems, you may want to reduce the size
of your dev test set.  After all you only want a representative sample to
estimate the mixture coeffs.

> It seems that the final ppl will not less than that from word-based
> trigram (4.80), in other words, there is no minimum between the two end

The ppl *MUST* be at most as large as either of the individual values in
your case, unless the probabilities in your ppl files have been messed up.
In the worst case if the algorithm decides that either model is useless, it
will converge to a lambda of 0 for it.

Please check.

&