The last weight from the phrase-table corresponds to the phrase penalty as explained in
http://www.statmt.org/moses/?n=FactoredTraining.ScorePhrases This features benefits translations that use less units to decode. It is the Euler's number and it is determined as such because the decoder uses natural logarithms to add the weights, instead of multiplying probabilities. Hence, 2.718 will become 1 during decoding as a way of saying "I'm using yet another phrase unit to perform a translation". So you were quite right after all :o) -- Carlos A. Henríquez Q. [email protected] ________________________________ De: Calia <[email protected]> Para: [email protected] Enviado: lun,22 febrero, 2010 05:26 Asunto: [Moses-support] 2.718 in the phrase-table The exact purpose of the value 2.718 is what I am not sure of. As far as I know, the value is used for preferring the hypothesis with less phrases to the one that use more phrases(words) for the same coverage of the source sentence during the prefix cost comparison inside priority queue( for the hyps that covers the same source range ). for example ) hyp1(I love you -> phrase_1 + phrase_2 ) vs hyp2(I love you -> phrase_1 + phrase_2 + phrase_3 ) to prefer hyp1 to hyp2 by multiplying hyp1 by 2.718. This is how I understand the use of the value, since longer phrase has empirically better translation than the one made up of word-based translation. Is there any one who can confirm my belief, or to correct my conclusion? p.s. Is 2.718 the Euler's number? If it is, why is the weight determined as such?
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