Dear Sara, Thanks for your helps, it was very helpful and worthless for us.
But about this part: the standard reordering model in Moses is inconsistent, since it is based on word alignments at training time, but on phrase alignments at decoding time. I checked the link too, you are right. but: Are you sure? Is it really the case? You mean since 2008 till now the moses code is not updated? On Thu, Sep 1, 2011 at 4:22 PM, Sara Stymne <[email protected]> wrote: > Hi, > > I have the same experience, that the lexical reordering model does not > always improve over only using the distance based model. I really think > it depends to a large extent on the language pair and the corpus. Of > course there is also the uncertainty of Mert, so it might be worthwhile > to run several Mert runs if you haven't done that already. > > I was in a team at the Dublin MT Marathon who worked on extending the > reordering models in Moses. Galley and Manning > (http://www.aclweb.org/anthology/D/D08/D08-1089.pdf) pointed out that > the standard reordering model in Moses is inconsistent, since it is > based on word alignments at training time, but on phrase alignments at > decoding time. Our group implemented both a consistent phrase-based > model, and the hierarchical reordering model suggested by Galley and > Manning. > > This code is in the Moses trunk, but the Moses webpage has not been > updated. There is some documentation on the MT Marathon wiki, however: > http://statmt.org/mtm4/?n=Main.HierarchicalReordering. I think it might > be worth it to investigate these models as well. > > There is some smoothing going on when training the reordering models. > There is a flag to train-model.perl: --reordering-smooth to set the > behavior of the smoothing. There is no proper treatment of unseen > phrases at decoding time though, which isn't that much of an issue if > the same data is used for training the phrase table and the reordering > model, since there won't be any unknown phrase pairs, except for > pass-through OOVs, then. But I think it would be a good idea to look > into that anyway. It was one thing we discussed at MT Marathon, but > never had time to do something about. > > /Sara > > > > > 2011-08-31 14:00, Neda NoorMohammadi skrev: > > Hello all, > > > > We are testing different reordering models in our system ( source > > language structure is sov and target is svo). > > The results are amazing! The distance based model improves the results > > in compare to lexical reordering models. > > > > we want to know is it true for other pair languages and also: > > Isn't it true that lexical reordering is offered to improve the > > reordering models? Then why we have get just the reverse?! How we can > > argument why it has happend to our system? > > > > Also I have checked the LexicalReorderingState.cpp class. There is a > > commented part in the code which shows it has uses no smoothing model > > for estimating none-seen events of this model. Am I right? > > > > Thanks > > > _______________________________________________ > Moses-support mailing list > [email protected] > http://mailman.mit.edu/mailman/listinfo/moses-support >
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