Proceedings of the 5th Conference of the Association for Machine Translation in the Americas: Technical Papers

Stephen D. Richardson (Editor)

Anthology ID:
October 8-12
Tiburon, USA
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Automatic rule learning for resource-limited MT
Jaime Carbonell | Katharina Probst | Erik Peterson | Christian Monson | Alon Lavie | Ralf Brown | Lori Levin

Machine Translation of minority languages presents unique challenges, including the paucity of bilingual training data and the unavailability of linguistically-trained speakers. This paper focuses on a machine learning approach to transfer-based MT, where data in the form of translations and lexical alignments are elicited from bilingual speakers, and a seeded version-space learning algorithm formulates and refines transfer rules. A rule-generalization lattice is defined based on LFG-style f-structures, permitting generalization operators in the search for the most general rules consistent with the elicited data. The paper presents these methods and illustrates examples.

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Toward a hybrid integrated translation environment
Michael Carl | Andy Way | Reinhard Schäler

In this paper we present a model for the future use of Machine Translation (MT) and Computer Assisted Translation. In order to accommodate the future needs in middle value translations, we discuss a number of MT techniques and architectures. We anticipate a hybrid environment that integrates data- and rule-driven approaches where translations will be routed through the available translation options and consumers will receive accurate information on the quality, pricing and time implications of their translation choice.

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Adaptive bilingual sentence alignment
Thomas C. Chuang | G.N. You | Jason Chang

We present a new approach to the problem of aligning English and Chinese sentences in a bilingual corpus based on adaptive learning. While using length information alone produces surprisingly good results for aligning bilingual French and English sentences with success rates well over 95%, it does not fair as well for the alignment of English and Chinese sentences. The crux of the problem lies in greater variability of lengths and match types of the matched sentences. We propose to cope with such variability via a two-pass scheme under which model parameters can be learned from the data at hand. Experiments show that under the approach bilingual English-Chinese texts can be aligned effectively across diverse domains, genres and translation directions with accuracy rates approaching 99%.

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DUSTer: a method for unraveling cross-language divergences for statistical word-level alignment
Bonnie Dorr | Lisa Pearl | Rebecca Hwa | Nizar Habash

The frequent occurrence of divergenceS—structural differences between languages—presents a great challenge for statistical word-level alignment. In this paper, we introduce DUSTer, a method for systematically identifying common divergence types and transforming an English sentence structure to bear a closer resemblance to that of another language. Our ultimate goal is to enable more accurate alignment and projection of dependency trees in another language without requiring any training on dependency-tree data in that language. We present an empirical analysis comparing the complexities of performing word-level alignments with and without divergence handling. Our results suggest that our approach facilitates word-level alignment, particularly for sentence pairs containing divergences.

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Text prediction with fuzzy alignment
George Foster | Philippe Langlais | Guy Lapalme

Text prediction is a form of interactive machine translation that is well suited to skilled translators. In recent work it has been shown that simple statistical translation models can be applied within a usermodeling framework to improve translator productivity by over 10% in simulated results. For the sake of efficiency in making real-time predictions, these models ignore the alignment relation between source and target texts. In this paper we introduce a new model that captures fuzzy alignments in a very simple way, and show that it gives modest improvements in predictive performance without significantly increasing the time required to generate predictions.

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Efficient integration of maximum entropy lexicon models within the training of statistical alignment models
Ismael García-Varea | Franz J. Och | Hermann Ney | Francisco Casacuberta

Maximum entropy (ME) models have been successfully applied to many natural language problems. In this paper, we show how to integrate ME models efficiently within a maximum likelihood training scheme of statistical machine translation models. Specifically, we define a set of context-dependent ME lexicon models and we present how to perform an efficient training of these ME models within the conventional expectation-maximization (EM) training of statistical translation models. Experimental results are also given in order to demonstrate how these ME models improve the results obtained with the traditional translation models. The results are presented by means of alignment quality comparing the resulting alignments with manually annotated reference alignments.

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Using word formation rules to extend MT lexicons
Claudia Gdaniec | Esmé Manandise

In the IBM LMT Machine Translation (MT) system, a built-in strategy provides lexical coverage of a particular subset of words that are not listed in its bilingual lexicons. The recognition and coding of these words and their transfer generation is based on a set of derivational morphological rules. A new utility extends unfound words of this type in an LMT-compatible format in an auxiliary bilingual lexical file to be subsequently merged into the core lexicons. What characterizes this approach is the use of morphological, semantic, and syntactic features for both analysis and transfer. The auxiliary lexical file (ALF) has to be revised before a merge into the core lexicons. This utility integrates a linguistics-based analysis and transfer rules with a corpus-based method of verifying or falsifying linguistic hypotheses against extensive document translation, which in addition yields statistics on frequencies of occurrence as well as local context.

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Example-based machine translation via the Web
Nano Gough | Andy Way | Mary Hearne

One of the limitations of translation memory systems is that the smallest translation units currently accessible are aligned sentential pairs. We propose an example-based machine translation system which uses a ‘phrasal lexicon’ in addition to the aligned sentences in its database. These phrases are extracted from the Penn Treebank using the Marker Hypothesis as a constraint on segmentation. They are then translated by three on-line machine translation (MT) systems, and a number of linguistic resources are automatically constructed which are used in the translation of new input. We perform two experiments on testsets of sentences and noun phrases to demonstrate the effectiveness of our system. In so doing, we obtain insights into the strengths and weaknesses of the selected on-line MT systems. Finally, like many example-based machine translation systems, our approach also suffers from the problem of ‘boundary friction’. Where the quality of resulting translations is compromised as a result, we use a novel, post hoc validation procedure via the World Wide Web to correct imperfect translations prior to their being output to the user.

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Handling translation divergences: combining statistical and symbolic techniques in generation-heavy machine translation
Nizar Habash | Bonnie Dorr

This paper describes a novel approach to handling translation divergences in a Generation-Heavy Hybrid Machine Translation (GHMT) system. The translation divergence problem is usually reserved for Transfer and Interlingual MT because it requires a large combination of complex lexical and structural mappings. A major requirement of these approaches is the accessibility of large amounts of explicit symmetric knowledge for both source and target languages. This limitation renders Transfer and Interlingual approaches ineffective in the face of structurally-divergent language pairs with asymmetric resources. GHMT addresses the more common form of this problem, source-poor/targetrich, by fully exploiting symbolic and statistical target-language resources. This non-interlingual non-transfer approach is accomplished by using target-language lexical semantics, categorial variations and subcategorization frames to overgenerate multiple lexico-structural variations from a target-glossed syntactic dependency of the source-language sentence. The symbolic overgeneration, which accounts for different possible translation divergences, is constrained by a statistical target-language model.

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Korean-Chinese machine translation based on verb patterns
Changhyun Kim | Munpyo Hong | Yinxia Huang | Young Kil Kim | Sung Il Yang | Young Ae Seo | Sung-Kwon Choi

This paper describes our ongoing project “Korean-Chinese Machine Translation System”. The main knowledge of our system is verb patterns. Each verb can have several meanings and each meaning of a verb is represented by a verb pattern. A verb pattern consists of a source language pattern part for the analysis and the corresponding target language pattern part for the generation. Each pattern part, according to the degree of generality, contains lexical or semantic information for the arguments or adjuncts of each verb meaning. In this approach, accurate analysis can directly lead to natural and correct generation. Furthermore as the transfer mainly depends upon verb patterns, the translation rate is expected to go higher, as the size of verb pattern grows larger.

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Merging example-based and statistical machine translation: an experiment
Philippe Langlais | Michel Simard

Despite the exciting work accomplished over the past decade in the field of Statistical Machine Translation (SMT), we are still far from the point of being able to say that machine translation fully meets the needs of real-life users. In a previous study [6], we have shown how a SMT engine could benefit from terminological resources, especially when translating texts very different from those used to train the system. In the present paper, we discuss the opening of SMT to examples automatically extracted from a Translation Memory (TM). We report results on a fair-sized translation task using the database of a commercial bilingual concordancer.

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Classification approach to word selection in machine translation
Hyo-Kyung Lee

We present a classification approach to building a English-Korean machine translation (MT) system. We attempt to build a word-based MT system from scratch using a set of parallel documents, online dictionary queries, and monolingual documents on the web. In our approach, MT problem is decomposed into two sub-problems — word selection problem and word ordering problem of the selected words. In this paper, we will focus on the word selection problem and discuss some preliminary results.

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Better contextual translation using machine learning
Arul Menezes

One of the problems facing translation systems that automatically extract transfer mappings (rules or examples) from bilingual corpora is the trade-off between contextual specificity and general applicability of the mappings, which typically results in conflicting mappings without distinguishing context. We present a machine-learning approach to choosing between such mappings, using classifiers that, in effect, selectively expand the context for these mappings using features available in a linguistic representation of the source language input. We show that using these classifiers in our machine translation system significantly improves the quality of the translated output. Additionally, the set of distinguishing features selected by the classifiers provides insight into the relative importance of the various linguistic features in choosing the correct contextual translation.

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Fast and accurate sentence alignment of bilingual corpora
Robert C. Moore

We present a new method for aligning sentences with their translations in a parallel bilingual corpus. Previous approaches have generally been based either on sentence length or word correspondences. Sentence-length-based methods are relatively fast and fairly accurate. Word-correspondence-based methods are generally more accurate but much slower, and usually depend on cognates or a bilingual lexicon. Our method adapts and combines these approaches, achieving high accuracy at a modest computational cost, and requiring no knowledge of the languages or the corpus beyond division into words and sentences.

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Deriving semantic knowledge from descriptive texts using an MT system
Eric Nyberg | Teruko Mitamura | Kathryn Baker | David Svoboda | Brian Peterson | Jennifer Williams

This paper describes the results of a feasibility study which focused on deriving semantic networks from descriptive texts using controlled language. The KANT system [3,6] was used to analyze input paragraphs, producing sentence-level interlingua representations. The interlinguas were merged to construct a paragraph-level representation, which was used to create a semantic network in Conceptual Graph (CG) [1] format. The interlinguas are also translated (using the KANTOO generator) into OWL statements for entry into the Ontology Works electrical power factbase [9]. The system was extended to allow simple querying in natural language.

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Using a large monolingual corpus to improve translation accuracy
Radu Soricut | Kevin Knight | Daniel Marcu

The existence of a phrase in a large monolingual corpus is very useful information, and so is its frequency. We introduce an alternative approach to automatic translation of phrases/sentences that operationalizes this observation. We use a statistical machine translation system to produce alternative translations and a large monolingual corpus to (re)rank these translations. Our results show that this combination yields better translations, especially when translating out-of-domain phrases/sentences. Our approach can be also used to automatically construct parallel corpora from monolingual resources.

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Semi-automatic compilation of bilingual lexcion entries from cross-lingually relevant news articles on WWW news sites
Takehito Utsuro | Takashi Horiuchi | Yasunobu Chiba | Takeshi Hamamoto

For the purpose of overcoming resource scarcity bottleneck in corpus-based translation knowledge acquisition research, this paper takes an approach of semi-automatically acquiring domain specific translation knowledge from the collection of bilingual news articles on WWW news sites. This paper presents results of applying standard co-occurrence frequency based techniques of estimating bilingual term correspondences from parallel corpora to relevant article pairs automatically collected from WWW news sites. The experimental evaluation results are very encouraging and it is proved that many useful bilingual term correspondences can be efficiently discovered with little human intervention from relevant article pairs on WWW news sites.

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Bootstrapping the lexicon building process for machine translation between ‘new’ languages
Ruvan Weerasinghe

The cumulative effort over the past few decades that have gone into developing linguistic resources for tasks ranging from machine readable dictionaries to translation systems is enormous. Such effort is prohibitively expensive for languages outside the (largely) European family. The possibility of building such resources automatically by accessing electronic corpora of such languages are therefore of great interest to those involved in studying these ‘new’ - ‘lesser known’ languages. The main stumbling block to applying these data driven techniques directly is that most of them require large corpora rarely available for such ‘new’ languages. This paper describes an attempt at setting up a bootstrapping agenda to exploit the scarce corpus resources that may be available at the outset to a researcher concerned with such languages. In particular it reports on results of an experiment to use state-of-the-art data-driven techniques for building linguistic resources for Sinhala - a non-European language with virtually no electronic resources.