OK - I see. But I can't tell you if it helps or not. I didn't do any systematic 
comparisons. Sorry.
Thanks for the explanation.

Jörg


Jörg Tiedemann
[email protected]




On Mar 6, 2014, at 7:37 PM, Barry Haddow wrote:

> Hi Jörg
> 
> In each MERT iteration, the first action is to decode the tuning set and 
> create an n-best list, using the current weight set. The 1-bests from 
> this decoding run are the hypotheses which get scored by --return-best-dev.
> 
> After that decoding, MERT searchs for a weight set that can rerank the 
> n-best lists to give a better BLEU, and stops when it reaches a local 
> maximum. This is the BLEU that is reported in the moses.ini file. So it 
> is a BLEU obtained by decoding with one weight set, and then reranking 
> with a different weight set. When you redecode using the new weight set 
> you do not get the same set of translations, since the nbest list is 
> just a tiny sample of the hypotheses that are considered during 
> decoding, so there will normally be hypotheses outwith the nbest list 
> which have higher model score.
> 
> We haven't generally used --return-best-dev with MERT - does it help? 
> It's really designed for pro and kbmira.
> 
> cheers - Barry
> 
> On 06/03/14 11:28, Jorg Tiedemann wrote:
>> Hi,
>> 
>> I have a question about the --return-best-dev flag in mert-moses.pl
>> I have run several experiments using this flag and I don't really 
>> understand how it influences the choice of settings during MERT. In 
>> many cases, the system will select an early iteration which is much 
>> below in terms of BLEU than many iterations later. Maybe my confusing 
>> is related to the BLEU score mentioned in the moses.ini files printed 
>> after each iteration? Can someone help me? Thanks!
>> 
>> 
>> Cheers,
>> Jörg
>> 
>> 
>> Jörg Tiedemann
>> [email protected] <mailto:[email protected]>
>> 
>> 
>> 
>> 
>> 
>> 
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