Nonparametric Word Segmentation for Machine Translation

Speaker: Thuylinh Nguyen
Title: Nonparametric Word Segmentation for Machine Translation
Thursday 18 Feb 2010. 12-1:30pm in GHC 4405.

In this talk we present an unsupervised word segmentation for machine
translation. The model utilizes existing nonparametric monolingual
segmentations. The monolingual segmentation model and the bilingual word
alignment model are coupled so that source text segmentation optimizes
the one-to-one mapping with the target text. Often, there are words in
the source language that do not appear in target language and vise
versa. Our model therefore models source language word deletion and word
insertion. The experiments show improvements on Arabic-English and
Chinese-English translation tasks.

LoonyBin: Making Empirical MT Reproducible, Efficient, and Less Annoying

Speaker: Jonathan Clark
When: Tuesday, January 19 at Noon
Where: GHC 6501
What: Free Knowledge and Free Food
Title: LoonyBin: Making Empirical MT Reproducible, Efficient, and
Less Annoying

Abstract: Construction of machine translation systems has evolved into
a multi-stage workflow involving many complicated dependencies. Many
decoder distributions have addressed this by including monolithic
training scripts – train-factored-model.pl for Moses and mr_runmer.pl
for SAMT. However, such scripts can be tricky to modify for novel
experiments and typically have limited support for the variety of job
schedulers found on academic and commercial computer clusters. Further
complicating these systems are hyperparameters, which often cannot be
directly optimized by conventional methods requiring users to
determine which combination of values is best via trial and error. The
recently-released LoonyBin open-source workflow management tool
addresses these issues by providing: 1) a visual interface for the
user to create and modify workflows; 2) a well-defined logging
mechanism; 3) a script generator that compiles visual workflows into
shell scripts, and 4) the concept of Hyperworkflows, which intuitively
and succinctly encodes small experimental variations within a larger
workflow. We also describe the Machine Translation Toolpack for
LoonyBin, which exposes state-of-the-art machine translation tools as
drag-and-drop components within LoonyBin.

MEMT and METEOR

Kenneth Heafield and Michael Denkowski: Features for System Combination
(This is work done as an MT lab project.)

Michael will give an update on his recent work on the METEOR MT evaluation matrix.

10 Dec 2009, Thursday, 12:00-1:30, in GHC 6501

Lori's talk

Speaker: Lori Levin
Where: GHC 6501
When: Nov 09, 2009 - Tuesday - Noon
Title: A Pendulum Swung Too Far
Abstract: This paper by Ken Church deals with the never ending battle between Empiricism and Rationalism,
esp. its incarnation in NLP. Lori will summarize and present the arguments formulated in the
paper. She will then continue with her own views on why linguistics
needs to be brought back into NLP and MT in particular.

Two talks

Talk 1:
Nguyen Bach: Source-side Dependency Tree Reordering Models with Subtree Movements and Constraints

Abstract: We propose a novel source-side dependency tree reordering model for statistical machine translation, in which subtree movements and constraints are represented as reordering events associated with the widely used lexicalized reordering models. This model allows us to not only efficiently capture the statistical distribution of the subtree-to-subtree transitions in training data, but also utilize it directly at the decoding time to guide the search process. Using subtree movements and constraints as features in a log-linear model, we are able to help the reordering models make better selections. It also allows the subtle importance of monolingual syntactic movements to be learned alongside other reordering features. We show improvements in translation quality in English-Spanish and English-Iraqi translation tasks.

This is joint work with Qin Gao and Stephan Vogel.

Talk 2:
Francisco (Paco) Guzman: Reassessment of the Role of Phrase Extraction in SMT

Abstract: In this paper we study in detail the relation between word alignment and phrase extraction. First, we analyze different word alignments according to several characteristics and compare them to hand-aligned data. Then, we analyze the phrase-pairs generated by these alignments. We observed that the number of unaligned words has a large impact on the characteristics of the phrase table. A manual evaluation of phrase pair quality showed that the increase in the number of unaligned words results in a lower quality. Finally, we present translation results from using the number of unaligned words as features from which we obtain up to 2BP of improvement.

This is joint work with Qin Gao and Stephan Vogel.

Making Disfluent Output Slightly Less So: MT System Combination Search Spaces and Optimization

Speaker: Kenneth Heafield

Title: Making Disfluent Output Slightly Less So:
MT System Combination Search Spaces and Optimization

Abstract: System combination merges several machine translation outputs
into a single improved sentence. This talk starts by summarizing the
approach including, a search space derived from the alignments, and
hypothesis scoring. The current search space focuses on picking words
in a roughly word synchronous way. Another search space under development
builds a directed graph in which aligned words correspond to a vertex and
each bigram corresponds to a directed edge. Search is conducted much like
a left-to-right MT decoder. Speed optimizations, which allow decoding at
5.5 sentences per second, apply to other MT systems in the areas of
duplicate handling, language model state, and multithreading. This speed
allows me to find hyperparameters by searching hundreds of parameter
combinations, each with a full round of tuning. In preparation for
last Friday's NIST submission, system combination improved 2.4 BLEU
points over the best component system for Urdu to English translation.

EBMT with external word alignment and chunk alignment

Title: EBMT with external word alignment and chunk alignment.

Who: Jae Dong Kim
When: Tuesday May 12, 12:00pm
Where: NSH 3305

Abstract: Since both EBMT and SMT are data driven methods, more accurate word alignment improves system performance in EBMT as in SMT. However, EBMT has focused on finding analogous examples while SMT has achieved plausibly accurate word alignment. For this reason, it is natural that one thinks that EBMT can benefit from using SMT word alignment. In this talk, I am going to talk about our approach to make use of more accurate external word alignment from SMT in our EBMT system. I am also going to talk about my preliminary results with chunk alignment for translation in EBMT.