you cannot backoff LM in the same way you can with phrase-tables. You
can specify both LMs, and they will both be used to score each
translation. They will both be tuned by MERT. It usually works ok
On 27/10/14 16:49, Tomas Fulajtar wrote:
Hi all,
I would like to combine two phrase based engines. One, smaller is
trained on desired domain data, but with limited corpus size. The
second is the legacy one with huge phrase table and LM, but with kind
of older/more obsolete terminology. Thus the idea is to combine both
to preserve domain/language style from the first engine, but also
reduce OOV with application of the second engine.
I think what I am looking for is the Back-off model - use the small
one as a preferred one , and then the second in case of phrases not
found. I have setup such a config in accordance with
http://www.statmt.org/moses/?n=Moses.AdvancedFeatures#ntoc25,.
[feature]
PhraseDictionaryCompact name=A
PhraseDictionaryCompact name=BackOff
[mapping]
0 T 0
1 T 1
[decoding-graph-backoff]
0
1
[weight]
A = 0 0 0 0
BackOff = 0 0 0 0
And it seems to work (weights were tuned afterwards with mert).
I have also read the
http://comments.gmane.org/gmane.comp.nlp.moses.user/10099
<http://comments.gmane.org/gmane.comp.nlp.moses.user/10099>. However
there is not mentioned how the LMs combination could be managed. I
can add both to ini file and perform the weights tuning, or is it
better to set the weights manually? I believe that phrase table
backoff would ensure the preference of model A terminology, while
combination of both LMs would make the translation smoother as it can
benefit from the second, bigger LM.
Could you please correct my assumptions? I hope the explanation does
make some senseā¦
Thank you very much,
Tomas
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