Hi Lane, As Vito mentioned, PhraseDictionaryMultiModel is originally for linear interpolation. It has an option to output all scores from all models rather than interpolating but I ended up writing PhraseDictionaryGroup to have the specific functionality plus some additions. One of the additions is the "default-average-others" option specifically for disjoint phrase tables. It will fill in scores for missing phrase pairs in any model by averaging the scores from other models. Empirically, this works better than zero-filling the scores or using a default score.
Another addition (which was never fully documented) is the "model-bitmap-count" option that adds indicator features for which models contain a phrase. For instance, if this option is enabled for 2 models, A and B, you have 3 features that will have the following scores when: - A phrase is in model A but *not* model B: 1 0 0 - A phrase is in *not* model A but is in model B: 0 1 0 - A phrase is in *both* models A and B: 0 0 1 Empirically, these help as well and batch MIRA does a fine job of finding weights for the expanded feature set. Best, Michael On Wed, Nov 16, 2016 at 11:32 AM, Vito Mandorino < vito.mandor...@linguacustodia.com> wrote: > Hi Lane, > > as far as I know the PhraseDictionaryMultiModel does a linear > interpolation of two or more phrase-tables at decoding time and is > equivalent to linearly interpolate the phrase-table beforehand, except > maybe for some pruning-related corner cases. > > If a translation option is not present in one of the phrase-tables, it is > considered as having zero (or very low, e.g. 10e-6) probability for that > phrase-table. I guess that the answer to your last question is yes, at > least in the general case (phrase-tables coming from training on a > bilingual corpus). > > Vito > > > 2016-11-16 16:41 GMT+01:00 Lane Schwartz <dowob...@gmail.com>: > >> Hi, >> >> I'm potentially interested in using PhraseDictionaryMultiModel, and how >> it differs from PhraseDictionaryGroup. >> >> With PhraseDictionaryMultiModel, is it OK to have disjoint phrase tables? >> That is, can PhraseDictionaryMultiModel handle the situation where a >> translation option is present in one table but not the other(s)? >> >> Thanks, >> Lane >> >> >> _______________________________________________ >> Moses-support mailing list >> Moses-support@mit.edu >> http://mailman.mit.edu/mailman/listinfo/moses-support >> >> > > > -- > *M**. Vito MANDORINO -- Chief Scientist* > > > [image: Description : Description : lingua_custodia_final full logo] > > *The Translation Trustee* > > *1, Place Charles de Gaulle, **78180 Montigny-le-Bretonneux* > > *Tel : +33 1 30 44 04 23 Mobile : +33 6 84 65 68 89 > <%2B33%206%2084%2065%2068%2089>* > > *Email :* *vito.mandor...@linguacustodia.com > <massinissa.ah...@linguacustodia.com>* > > *Website :* > *www.linguacustodia.finance <http://www.linguacustodia.com/>* > > _______________________________________________ > Moses-support mailing list > Moses-support@mit.edu > http://mailman.mit.edu/mailman/listinfo/moses-support > >
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