Re: Student - Doubts regarding Statistical Machine
hi ravi,
i don't think i can go through in as much details as you would wish.
if u want to find out more, i would advise u to look thru the code.
for stuff relating to re-combination, look at the function
void HypothesisStack::AddPrune(Hypothesis *hypo)
in HypothesisStack.cpp
The comparison of 2 hypotheses to determine whether they are 'the same'
so should be recombined is in the class
HypothesisRecombinationOrderer
In HypothesisStack.h
The pharaoh manual has explanation of recombination, the moses
implementation follows this closely.
Hopes that helps
Hieu Hoang
www.hoang.co.uk/hieu
-----Original Message-----
From: moses-support-bounces@...
[mailto:moses-support-bounces@...] On Behalf Of ravi agarwal
Sent: 05 April 2007 19:04
To: moses-support@...
Subject: Re: [Moses-support] Student - Doubts regarding Statistical
Machine
Reply of Message 2 - regarding A1.
Sir, I am still confused of what do you mean by worse scores. Kindly
give me example particular to the concerned case of 'das ist ein kleines
haus' to 'This is a small house'.
e.g. -> In the 4th stack, hypothesis 312 with final score -42.55 (-38.29
-4.26) is discarded, where as hypothesis 93 with final score -48.12
(-32.94 -15.18) is added. So, I really do not understand, which is
discarded and how to decide, which one is "too bad for stack".
I mean, there are several instances, when hypothesis of lesser (i.e.
good) final score is discarded and of more (bad) final score is added.
I request you to please explain it to me, giving hypothesis number,
which is discarded in comparison and why.
Thanks & Regards
Ravi Agarwal
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Today's Topics:
1. Re: Understanding decoder output fields (Hieu Hoang)
2. Re: Student - Doubts regarding Statistical Machine
Translation - Decoder - Moses (Hieu Hoang)
3. Re: Student - Doubts regarding Statistical Machine
Translation - Decoder - Moses (Hieu Hoang)
----------------------------------------------------------------------
Message: 1
Date: Tue, 3 Apr 2007 21:27:08 +0100
From: "Hieu Hoang"
Subject: Re: [Moses-support] Understanding decoder output fields
To: "'Lane Schwartz'" , "'moses-support'"
Message-ID: <001501c7762e$73b98620$05000100 <at> very>
Content-Type: text/plain; charset="iso-8859-1"
Hi lane,
The scores are listed in the following order:
1. basic distortion
2. reordering
3. language models
4. phrase tables
5. word penalty
6. generation tables
I believe that's the order in which they're loaded, but it may not be
noticeable from the debugging output.
The order can be verified in the function
IOStream::OutputNBestList()
In the file
IOStream.cpp
If u add a
-labeled-n-best-list 1
The array of 15 numbers is annotated with some info of what they refer
to.
Hope that helps
Hieu Hoang
www.hoang.co.uk/hieu
-----Original Message-----
From: moses-support-bounces@...
[mailto:moses-support-bounces@...] On Behalf Of Lane Schwartz
Sent: 03 April 2007 16:57
To: moses-support
Subject: [Moses-support] Understanding decoder output fields
When moses decodes a sentence, and produces an BEST TRANSLATION, it
gives a total score, as well as an array of 15 other numbers.
I'm trying to figure out which of those 15 numbers is the target
language model score for the translation.
Here's what I get when I run the decoder:
Defined parameters (per moses.ini or switch):
config: /export/scratch/moses.nc.fr-en/working-dir/
evaluation/filtered.nc-devtest2007/moses.ini
distortion-file: 0-0 msd-bidirectional-fe 6 /export/scratch/
moses.nc.fr-en/working-dir/evaluation/filtered.nc-devtest2007/
reordering-table.msd-bidirectional-fe.0.5.0-0
distortion-limit: 6
input-factors: 0
input-file: /export/scratch/moses.nc.fr-en/working-dir/
evaluation/nc-devtest2007.input
lmodel-file: 0 0 5 /export/scratch/moses.nc.fr-en/working-
dir/lm/europarl-v3.lm
mapping: 0 T 0
ttable-file: 0 0 5 /export/scratch/moses.nc.fr-en/working-
dir/evaluation/filtered.nc-devtest2007/phrase-table.0-0
ttable-limit: 20 0
weight-d: 0.086065 0.110904 -0.015132 0.075996 0.115685
0.056790 0.024530
weight-l: 0.107263
weight-t: 0.019468 0.102550 0.127223 0.020522 0.060418
weight-w: 0.077454
Start loading distortion table /export/scratch/moses.nc.fr-en/working-
dir/evaluation/filtered.nc-devtest2007/reordering-table.msd-
bidirectional-fe.0.5.0-0: [0.000] seconds
Start loading LanguageModel /export/scratch/moses.nc.fr-en/working-
dir/lm/europarl-v3.lm: [3.000] seconds
Finished loading LanguageModels : [18.000] seconds
Start loading PhraseTable /export/scratch/moses.nc.fr-en/working-dir/
evaluation/filtered.nc-devtest2007/phrase-table.0-0: [18.000] seconds
Finished loading phrase tables : [24.000] seconds Created input-output
object : [24.000] seconds
Translating: apprivoiser les politiciens des deux c?t?s de l' atlantique
BEST TRANSLATION: taming politicians on both sides of the atlantic
[111111111] [total=-7.621] <<0.000, -8.000, 0.000, -1.585, 0.000,
0.000, -1.820, 0.000, 0.000, -46.545, -3.730, -12.789, -1.979,
-11.109, 4.000>>
Finished translating
Thanks,
Lane Schwartz
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------------------------------
Message: 2
Date: Tue, 3 Apr 2007 21:54:39 +0100
From: "Hieu Hoang"
Subject: Re: [Moses-support] Student - Doubts regarding Statistical
Machine Translation - Decoder - Moses
To:
Cc: 'moses-support'
Message-ID: <001601c77632$4e715100$05000100 <at> very>
Content-Type: text/plain; charset="US-ASCII"
Haven't been knighted by the queen yet. But Sir is a good title for
me...
A1.
Hypos are discarded when the number of hypos in a stack is twice as high
as the beam size.
The hypos with the worst scores are thrown away. The scores are pretty
simple to understand except 1 - the future score. However, this is
critical to making sure good results are obtained.
The scores are described in the pharaoh manual.
A2.
We expand all hypotheses in the previous stack. The order is dependant
on the iterator of the stack, which is dependant on how hypotheses are
compared for recombination. However, u should view the order as
arbitary.
I suppose this could affect the final outcome of the decoder - however,
I think the difference is small.
A3. If you have a trigram LM scoring the target sentence, then the last
2 target words translated is the only thing that can influence the LM
score of future hypos.
For example, 2 hypos with the following target sentence is guaranteed to
have the same incremental LM score going forward:
This is a
That is a
Because adding 'house' means both hypos will have an additional trigram
of
is a house
If the LM is a 4-gram, then the next 3 target words is important. If the
LM is a 100-gram, then the next 99 words is important.
In fact, moses is cleverer than the algorithm described above, the logic
of which I'm not going to go into.
Moses can also handle multiple LMs,
For now, the above explanation is a good starting point.
The code for reconbination is in the class
HypothesisRecombinationOrderer
In file
HypothesisStack.h
Hieu Hoang
www.hoang.co.uk/hieu
-----Original Message-----
From: Ravi Agarwal [mailto:ravi_agarwal@...]
Sent: 03 April 2007 11:37
To: hieuhoang1972@...
Subject: Student - Doubts regarding Statistical Machine Translation -
Decoder - Moses
Importance: High
Hello Sir Hoang,
This is Ravi Agarwal, a B.Tech Final year student in Computer
Science from Dhirubhai Ambani Institute Of Information and Communication
Technology, India. I request you to please clarify some of my doubts.
My final year project is to implement a Toy Decoder on
Statistical Machine Translation. I have read the 'User Manual' of
Pharaoh properly, and am performing experiments on the source code of
Moses. On executing the following command on the sample model provided
on Moses 'Get Started' web page - command : moses -f moses.ini -v 3
A detailed description of partial hypotheses is generated. I saved
this description in a file 'BehindDecoding.txt'. I've following doubts
regarding partial hypothesis building. You can answer my doubts in
respect to this saved file itself i.e. for this particular case of
example 'das ist ein kleines haus' to 'This is a small house'.
Q1 - On what basis hypotheses (partial translations) are discarded from
a stack ? Q2 - When we start processing a new stack, the hypothesis from
the previous stack are expanded. In which order, do you pick the
previous hypothesis i.e. how do you decide which hypothesis should be
expanded first ? Is it order inspecific ? Q3 - I am not exactly very
clear about when to recombine the hypotheses. In user manual of Pharaoh,
you have explained 3 points to be considered for recombining, But what
do you mean by the second point - 'the last two English words generated
?' Last two word counts presently translated word or just past two
words.
Moreover, Do you think that just for the specific example taken
- 'das ist ein kleines haus' to 'This is a small house', can we think of
some alternate condition for recombining. I mean the same conditions but
with some bypass due to the particular case.
If you are unable to understand my Q3, do not worry, may be I am
unable to explain it properly. Q4 - What is the use of the best
hypothesis. I mean the best hypothesis in the final stack gives us the
final and best translation of the given input foreign language sentence.
But what is the use of best hypothesis in the intermediate stacks ?
Please clarify my doubts.
Kindly look into the matter.
I will be highly obliged by you.
Thanking You.
Sincerely,
Ravi Agarwal
BTech - Final Year (Computer Science)
Dhirubhai Ambani Institute Of Information and Communication Technology
Gujarat, India. http://www.daiict.ac.in Tel : (+91) 9924125684 gmail
users : ravi.rickie@...
------------------------------
Message: 3
Date: Tue, 3 Apr 2007 21:57:00 +0100
From: "Hieu Hoang"
Subject: Re: [Moses-support] Student - Doubts regarding Statistical
Machine Translation - Decoder - Moses
To:
Cc: 'moses-support'
Message-ID: <001701c77632$a012af90$05000100 <at> very>
Content-Type: text/plain; charset="US-ASCII"
Ps. Please email questions to the 'moses-support' mailing list, rather
than directly to me.
I've got a spam filter which is highly likely to trash your mail if it
not from 'moses-support' and I've never emailed u before
Hieu Hoang
www.hoang.co.uk/hieu
-----Original Message-----
From: Hieu Hoang [mailto:h.hoang@...]
Sent: 03 April 2007 21:55
To: 'ravi_agarwal@...'
Cc: 'moses-support'
Subject: RE: Student - Doubts regarding Statistical Machine Translation
- Decoder - Moses
Haven't been knighted by the queen yet. But Sir is a good title for
me...
A1.
Hypos are discarded when the number of hypos in a stack is twice as high
as the beam size. The hypos with the worst scores are thrown away. The
scores are pretty simple to understand except 1 - the future score.
However, this is critical to making sure good results are obtained.
The scores are described in the pharaoh manual.
A2.
We expand all hypotheses in the previous stack. The order is dependant
on the iterator of the stack, which is dependant on how hypotheses are
compared for recombination. However, u should view the order as
arbitary.
I suppose this could affect the final outcome of the decoder - however,
I think the difference is small.
A3. If you have a trigram LM scoring the target sentence, then the last
2 target words translated is the only thing that can influence the LM
score of future hypos.
For example, 2 hypos with the following target sentence is guaranteed to
have the same incremental LM score going forward:
This is a
That is a
Because adding 'house' means both hypos will have an additional trigram
of
is a house
If the LM is a 4-gram, then the next 3 target words is important. If the
LM is a 100-gram, then the next 99 words is important.
In fact, moses is cleverer than the algorithm described above, the logic
of which I'm not going to go into.
Moses can also handle multiple LMs,
For now, the above explanation is a good starting point.
The code for reconbination is in the class
HypothesisRecombinationOrderer
In file
HypothesisStack.h
Hieu Hoang
www.hoang.co.uk/hieu
-----Original Message-----
From: Ravi Agarwal [mailto:ravi_agarwal@...]
Sent: 03 April 2007 11:37
To: hieuhoang1972@...
Subject: Student - Doubts regarding Statistical Machine Translation -
Decoder - Moses
Importance: High
Hello Sir Hoang,
This is Ravi Agarwal, a B.Tech Final year student in Computer
Science from Dhirubhai Ambani Institute Of Information and Communication
Technology, India. I request you to please clarify some of my doubts.
My final year project is to implement a Toy Decoder on
Statistical Machine Translation. I have read the 'User Manual' of
Pharaoh properly, and am performing experiments on the source code of
Moses. On executing the following command on the sample model provided
on Moses 'Get Started' web page - command : moses -f moses.ini -v 3
A detailed description of partial hypotheses is generated. I saved
this description in a file 'BehindDecoding.txt'. I've following doubts
regarding partial hypothesis building. You can answer my doubts in
respect to this saved file itself i.e. for this particular case of
example 'das ist ein kleines haus' to 'This is a small house'.
Q1 - On what basis hypotheses (partial translations) are discarded from
a stack ? Q2 - When we start processing a new stack, the hypothesis from
the previous stack are expanded. In which order, do you pick the
previous hypothesis i.e. how do you decide which hypothesis should be
expanded first ? Is it order inspecific ? Q3 - I am not exactly very
clear about when to recombine the hypotheses. In user manual of Pharaoh,
you have explained 3 points to be considered for recombining, But what
do you mean by the second point - 'the last two English words generated
?' Last two word counts presently translated word or just past two
words.
Moreover, Do you think that just for the specific example taken
- 'das ist ein kleines haus' to 'This is a small house', can we think of
some alternate condition for recombining. I mean the same conditions but
with some bypass due to the particular case.
If you are unable to understand my Q3, do not worry, may be I am
unable to explain it properly. Q4 - What is the use of the best
hypothesis. I mean the best hypothesis in the final stack gives us the
final and best translation of the given input foreign language sentence.
But what is the use of best hypothesis in the intermediate stacks ?
Please clarify my doubts.
Kindly look into the matter.
I will be highly obliged by you.
Thanking You.
Sincerely,
Ravi Agarwal
BTech - Final Year (Computer Science)
Dhirubhai Ambani Institute Of Information and Communication Technology
Gujarat, India. http://www.daiict.ac.in Tel : (+91) 9924125684 gmail
users : ravi.rickie@...
------------------------------
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