*mystified* 2009/2/17 Hieu Hoang <[email protected]>: > therefore, including every lm score is a better estimator of the > future cost than only including the trigram, even though the unigram > and bigram will not eventually be used. > > > > > On 17/02/2009, Hieu Hoang <[email protected]> wrote: >> i think you're asking why the unigram and bigram LM scores of the 1st two >> words are used to calculate future scores when the LM is a trigram. >> >> that's a good question & 1 i've revisited recently with the hierarchical >> moses. >> >> i'm not sure there's a good theoretical basis for it. however, the future >> score is also used to prune certain phrase pairs before decoding to speed up >> the process. Including the unigram and bigram score definately help in >> ensuring good translations aren't pruned. >> >> >> Hieu Hoang >> www.hoang.co.uk/hieu >> >> >> _____ >> >> From: [email protected] [mailto:[email protected]] >> On Behalf Of Ergun Bicici >> Sent: 17 February 2009 13:10 >> To: Philipp Koehn >> Cc: [email protected] >> Subject: Re: [Moses-support] Future costs calculation in MOSES >> >> >> >> Hi Philipp, >> >> Thanks for the response. I was not asking why these scores are cached. >> >> My question is more about why calculate this way. Is this because of an >> admissible heuristic? >> >> Ergun Bicici >> Koc University >> >> >> >> On Wed, Feb 11, 2009 at 11:51 PM, Philipp Koehn <[email protected]> wrote: >> >> >> Hi, >> >> what is going here is a caching of phrase-internal >> n-gram model scores, so they do not have to be >> re-computed. Think about the output phrase >> "the very big and funny man" - if you use a trigram >> language model, then the computation of the language >> model scores for the words "big", "and", "funny", "man" >> are the same, no matter what the context. So, these are >> cached. >> >> -phi >> >> >>> LanguageModel::CalcScore is adding ngram score to retFull score: >>> fullScore += ngramScore; >>> >>> But then in TranslationOption::CalcScore, this is subtracted back: >>> m_futureScore = retFullScore - ngramScore >>> + >>> m_scoreBreakdown.InnerProduct(StaticData::Instance().GetAllWeights()) - >>> phraseSize * StaticData::Instance().GetWeightWordPenalty(); >>> >>> >>> - Is the n-gram order (3) fixed for LM cost calculations >>> used in future cost? It does not look so. >>> >>> >>> It would be helpful if someone could clarify the >>> future cost calculation further. >>> >>> Thanks, >>> Ergun >>> >>> >>> Ergun Bicici >>> Koc University >>> >>> >>> On Wed, Sep 24, 2008 at 5:46 PM, Philipp Koehn <[email protected]> >> wrote: >>>> >>>> Hi, >>>> >>>> the future cost estimates includes an estimate of the phrase translation >>>> cost >>>> and language model cost, but not reordering costs. And yes, this is >>>> implemented >>>> as described in the Pharaoh manual. >>>> >>>> -phi >>>> >>>> On Wed, Sep 24, 2008 at 8:58 AM, Yee Seng Chan <[email protected]> >>>> wrote: >>>> > Hi list members, >>>> > >>>> > >>>> > >>>> > Inside TranslationOption.cpp::CalcScore(), m_futureScore is >> effectively: >>>> > retFullScore - (PhraseSize*WordPenalty) >>>> > >>>> > (Kindly correct me if I'm wrong). >>>> > >>>> > >>>> > >>>> > What's the reasoning for using the above as futureScore? I know >>>> > retFullScore >>>> > is n-gram score. Btw, does the approach here follows "Section 3.5 >> Future >>>> > Cost Estimation" in the Pharaoh manual? >>>> > >>>> > >>>> > >>>> > Best regards, >>>> > >>>> > Yee Seng Chan >>>> > >>>> > >>>> > >>>> > _______________________________________________ >>>> > Moses-support mailing list >>>> > [email protected] >>>> > http://mailman.mit.edu/mailman/listinfo/moses-support >>>> > >>>> > >>>> _______________________________________________ >>>> Moses-support mailing list >>>> [email protected] >>>> http://mailman.mit.edu/mailman/listinfo/moses-support >>>> >>> >>> >>> _______________________________________________ >>> Moses-support mailing list >>> [email protected] >>> http://mailman.mit.edu/mailman/listinfo/moses-support >>> >>> >> >> >> >> >> > _______________________________________________ > Moses-support mailing list > [email protected] > http://mailman.mit.edu/mailman/listinfo/moses-support >
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