Moses-support Digest, Vol 110, Issue 30

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Today's Topics:

1. Slides or paper walking through
SearchNormal::ProcessOneHypothesis ? (Lane Schwartz)
2. Re: Slides or paper walking through
SearchNormal::ProcessOneHypothesis ? (Hieu Hoang)
3. Re: Slides or paper walking through
SearchNormal::ProcessOneHypothesis ? (Matthias Huck)
4. how to train with berkeley word aligner (Andrew)


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Message: 1
Date: Tue, 15 Dec 2015 14:59:09 -0600
From: Lane Schwartz <dowobeha@gmail.com>
Subject: [Moses-support] Slides or paper walking through
SearchNormal::ProcessOneHypothesis ?
To: "moses-support@mit.edu" <moses-support@mit.edu>
Message-ID:
<CABv3vZncUSwsARUiaXwKS9f3c_ZLm3-PgDRD1Fx+y8O0Ji8QBA@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Hey all,

So the SearchNormal::ProcessOneHypothesis() method in SearchNormal.cpp is
responsible for taking an existing hypothesis, creating all legal new
extension hypotheses, and adding those new hypotheses to the appropriate
decoder stacks.

First off, the method is actually reasonably well commented, so kudos to
whoever did that. :)

That said, does anyone happen to have any slides that actually walk through
this process, specifically slides that take into account the interaction
with the distortion limit? That interaction is where most of the complexity
of this method comes from. I don't know about others, but even having a
pretty good notion of what's going on here, the discussion of "the closest
thing to the left" is still a bit opaque.

Anyway, if anyone knows of a good set of slides, or even a good description
in a paper, of what's going on here, I'd appreciate any pointers.

Thanks,
Lane
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Message: 2
Date: Tue, 15 Dec 2015 22:33:04 +0000
From: Hieu Hoang <hieuhoang@gmail.com>
Subject: Re: [Moses-support] Slides or paper walking through
SearchNormal::ProcessOneHypothesis ?
To: Lane Schwartz <dowobeha@gmail.com>
Cc: "moses-support@mit.edu" <moses-support@mit.edu>
Message-ID:
<CAEKMkbgpJy5pAW7oP7rC6WtYxvfRbEt5mzp13jZjr_txE-KdTQ@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

I've been looking at this and it is surprisingly complicated. I think the
code is designed to predetermine if extending a hypothesis will lead it
down a path that won't ever be completed.

Don't know any slide that explains the reasoning, Philipp Koehn explained
it to me once and it seems pretty reasonable.


I wouldn't mind seeing this code cleaned up a bit and abstracted and
formalised. I've made a start with the cleanup in my new decoder

https://github.com/moses-smt/mosesdecoder/blob/perf_moses2/contrib/other-builds/moses2/Search/Search.cpp#L36
Search::CanExtend()

There was an Aachen paper from years ago comparing different distortion
limit heuristics - can't remember the authors or title. Maybe someone know
more



Hieu Hoang
http://www.hoang.co.uk/hieu

On 15 December 2015 at 20:59, Lane Schwartz <dowobeha@gmail.com> wrote:

> Hey all,
>
> So the SearchNormal::ProcessOneHypothesis() method in SearchNormal.cpp is
> responsible for taking an existing hypothesis, creating all legal new
> extension hypotheses, and adding those new hypotheses to the appropriate
> decoder stacks.
>
> First off, the method is actually reasonably well commented, so kudos to
> whoever did that. :)
>
> That said, does anyone happen to have any slides that actually walk
> through this process, specifically slides that take into account the
> interaction with the distortion limit? That interaction is where most of
> the complexity of this method comes from. I don't know about others, but
> even having a pretty good notion of what's going on here, the discussion of
> "the closest thing to the left" is still a bit opaque.
>
> Anyway, if anyone knows of a good set of slides, or even a good
> description in a paper, of what's going on here, I'd appreciate any
> pointers.
>
> Thanks,
> Lane
>
>
> _______________________________________________
> Moses-support mailing list
> Moses-support@mit.edu
> http://mailman.mit.edu/mailman/listinfo/moses-support
>
>
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Message: 3
Date: Tue, 15 Dec 2015 23:56:24 +0000
From: Matthias Huck <mhuck@inf.ed.ac.uk>
Subject: Re: [Moses-support] Slides or paper walking through
SearchNormal::ProcessOneHypothesis ?
To: Hieu Hoang <hieuhoang@gmail.com>
Cc: "moses-support@mit.edu" <moses-support@mit.edu>
Message-ID: <1450223784.2340.27.camel@inf.ed.ac.uk>
Content-Type: text/plain; charset="UTF-8"

Hi Lane,

Well, you can find excellent descriptions of phrase-based decoding
algorithms in the literature, though possibly not all details of this
specific implementation.

I like this description:

R. Zens, and H. Ney. Improvements in Dynamic Programming Beam Search for
Phrase-based Statistical Machine Translation. In International Workshop
on Spoken Language Translation (IWSLT), pages 195-205, Honolulu, HI,
USA, October 2008.
http://www.hltpr.rwth-aachen.de/publications/download/618/Zens-IWSLT-2008.pdf

It's what's implemented in Jane, RWTH's open source statistical machine
translation toolkit.

J. Wuebker, M. Huck, S. Peitz, M. Nuhn, M. Freitag, J. Peter, S.
Mansour, and H. Ney. Jane 2: Open Source Phrase-based and Hierarchical
Statistical Machine Translation. In International Conference on
Computational Linguistics (COLING), pages 483-491, Mumbai, India,
December 2012.
http://www.hltpr.rwth-aachen.de/publications/download/830/Wuebker-COLING-2012.pdf

However, I believe that the distinction of coverage hypotheses and
lexical hypotheses is a unique property of the RWTH systems.

The formalization in the Zens & Ney paper is very nicely done. With hard
distortion limits or coverage-based reordering constraints, you may need
a few more steps in the algorithm. E.g., if you have a hard distortion
limit, you will probably want to avoid leaving a gap and then extending
your sequence in a way that puts your current position further away from
the gap than your maximum jump width. Other people should know more
about how exactly Moses' phrase-based decoder is dealing with this.

I can recommend Richard Zens' PhD thesis as well.
http://www.hltpr.rwth-aachen.de/publications/download/562/Zens--2008.pdf

I also remember that the following publication from Microsoft Research
is pretty helpful:

Robert C. Moore and Chris Quirk, Faster Beam-Search Decoding for Phrasal
Statistical Machine Translation, in Proceedings of MT Summit XI,
European Association for Machine Translation, September 2007.
http://research.microsoft.com/pubs/68097/mtsummit2007_beamsearch.pdf

Cheers,
Matthias



On Tue, 2015-12-15 at 22:33 +0000, Hieu Hoang wrote:
> I've been looking at this and it is surprisingly complicated. I think
> the code is designed to predetermine if extending a hypothesis will
> lead it down a path that won't ever be completed.
>
>
> Don't know any slide that explains the reasoning, Philipp Koehn
> explained it to me once and it seems pretty reasonable.
>
>
>
> I wouldn't mind seeing this code cleaned up a bit and abstracted and
> formalised. I've made a start with the cleanup in my new decoder
>
> https://github.com/moses-smt/mosesdecoder/blob/perf_moses2/contrib/other-builds/moses2/Search/Search.cpp#L36
> Search::CanExtend()
>
>
> There was an Aachen paper from years ago comparing different
> distortion limit heuristics - can't remember the authors or title.
> Maybe someone know more
>
>
>
>
>
> Hieu Hoang
> http://www.hoang.co.uk/hieu
>
>
> On 15 December 2015 at 20:59, Lane Schwartz <dowobeha@gmail.com>
> wrote:
> Hey all,
>
>
> So the SearchNormal::ProcessOneHypothesis() method in
> SearchNormal.cpp is responsible for taking an existing
> hypothesis, creating all legal new extension hypotheses, and
> adding those new hypotheses to the appropriate decoder
> stacks.
>
>
> First off, the method is actually reasonably well commented,
> so kudos to whoever did that. :)
>
>
> That said, does anyone happen to have any slides that actually
> walk through this process, specifically slides that take into
> account the interaction with the distortion limit? That
> interaction is where most of the complexity of this method
> comes from. I don't know about others, but even having a
> pretty good notion of what's going on here, the discussion of
> "the closest thing to the left" is still a bit opaque.
>
>
> Anyway, if anyone knows of a good set of slides, or even a
> good description in a paper, of what's going on here, I'd
> appreciate any pointers.
>
>
> Thanks,
> Lane
>
>
>
> _______________________________________________
> Moses-support mailing list
> Moses-support@mit.edu
> http://mailman.mit.edu/mailman/listinfo/moses-support
>
>
>
> _______________________________________________
> Moses-support mailing list
> Moses-support@mit.edu
> http://mailman.mit.edu/mailman/listinfo/moses-support



--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.



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

Message: 4
Date: Wed, 16 Dec 2015 22:37:11 +0900
From: Andrew <ravenyj@hotmail.com>
Subject: [Moses-support] how to train with berkeley word aligner
To: "moses-support@mit.edu" <moses-support@mit.edu>
Message-ID: <BAY181-W632B592198A2DC8E62D5D4B2EF0@phx.gbl>
Content-Type: text/plain; charset="iso-2022-jp"

I'm replicating the steps described in Baseline System page,and am about to run the following command,except I want to run it with pre-compiled berkeley word aligner rather than mgiza or giza++ (since their installations have been troublesome)Should I fix the command below or code in somewhere?In any case, how should it be fixed?

mkdir ~/working
cd ~/working
nohup nice ~/mosesdecoder/scripts/training/train-model.perl -root-dir train \
-corpus ~/corpus/news-commentary-v8.fr-en.clean \
-f fr -e en -alignment grow-diag-final-and -reordering msd-bidirectional-fe \
-lm 0:3:$HOME/lm/news-commentary-v8.fr-en.blm.en:8 \
-external-bin-dir ~/mosesdecoder/tools >& training.out &
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