Moses-support Digest, Vol 107, Issue 11

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Today's Topics:

1. Re: [Moses-developers] Generation models with Mmsapt
(Michael Denkowski)


----------------------------------------------------------------------

Message: 1
Date: Thu, 3 Sep 2015 00:13:05 -0400
From: Michael Denkowski <michael.j.denkowski@gmail.com>
Subject: Re: [Moses-support] [Moses-developers] Generation models with
Mmsapt
To: Hieu Hoang <hieuhoang@gmail.com>
Cc: moses-support <moses-support@mit.edu>
Message-ID:
<CA+-Geg+rcUq36QfsvAJA_B23GqUTvVkrpC3rTVVowZ9w2DpK7w@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Sounds good. I added a small test model to my branch:
https://github.com/moses-smt/mosesdecoder/raw/mjdenkowski/mmsapt-factor-test.tar.gz.
This translates a sample of fr-en news with a Mmsapt, surface LM, and
400-class LM.

--Michael

On Wed, Sep 2, 2015 at 2:56 AM, Hieu Hoang <hieuhoang@gmail.com> wrote:

> It should work. The function
> EvaluateInIsolation()
> in the LM is for optimisation reason. eg. if the target phrase is 'a b c
> d' and the LM is a trigram, the trigrams 'a b c' and 'b c d' can be
> precalculated in EvaluateInIsolation().
>
> Implementing a pt for factors requires setting up some variables, which
> may not have happen yet in mmsapt. if you can send me a small example
> model, i'll see what i can do
>
>
> On 01/09/2015 02:11, Ulrich Germann wrote:
>
> Hi Michael,
>
> I have no experience with factored models, so I'm speculating here to some
> degree. The reason the phrase table calls EvaluateInIsolation is because
> all "isolated" phrase scores are considered when pruning. In my opinion
> pruning should not happen within the phrase tables (for exactly the reason
> that it does not allow feature functions to be agnostic about other feature
> functions) but by whatever object calls all the phrase tables and does the
> generation. However, for software legacy reasons, that's the way it is
> right now, and I'm not likely to address this issue any time soon myself.
> The most reasonable fix for this in my opinion is to move pruning where it
> belongs --- post all the factor generation stuff.
>
> Hieu is probably still the person with the best understanding of how
> factored phrase table entry generation works, so maybe he can chime in on
> this ...
>
> Cheers - Uli
>
>
> On Mon, Aug 31, 2015 at 11:29 PM, Michael Denkowski <
> <michael.j.denkowski@gmail.com>michael.j.denkowski@gmail.com> wrote:
>
>> Hi Ulrich,
>>
>> I was looking into using a class-based LM with your dynamic phrase table
>> via generation models. I translate factor 0 to 0 with the Mmsapt, then
>> generate target factor 1 (word class) with a GM. The class-based LM
>> operates on factor 1.
>>
>> I'm hitting a segfault on what appears to be an order-of-operations issue
>> with the PT and LM. In mmsapt.cpp:578, Mmsapt::mkTPhrase makes a call to
>> tp->EvaluateInIsolation. This calls all of the models, including the LMs.
>> The class LM tries to score factor 1, which doesn't exist yet (since
>> generation happens after translation), and it dies. By nature, other
>> phrase tables don't have this issue since they can just pull up
>> pre-computed scores.
>>
>> Is scoring with all of the models here a strategic choice to get better
>> performance or would it be sufficient to just score with the PT features?
>> Thanks!
>>
>> --Michael
>>
>
>
>
> --
> Ulrich Germann
> Senior Researcher
> School of Informatics
> University of Edinburgh
>
>
> _______________________________________________
> Moses-developers mailing listMoses-developers@mit.eduhttp://mailman.mit.edu/mailman/listinfo/moses-developers
>
>
> --
> Hieu Hoang
> Researcher
> New York University, Abu Dhabihttp://www.hoang.co.uk/hieu
>
>
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