Maja Popović

Also published as: Maja Popovic


2024

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Effects of different types of noise in user-generated reviews on human and machine translations including ChatGPT
Maja Popovic | Ekaterina Lapshinova-Koltunski | Maarit Koponen
Proceedings of the Ninth Workshop on Noisy and User-generated Text (W-NUT 2024)

This paper investigates effects of noisy source texts (containing spelling and grammar errors, informal words or expressions, etc.) on human and machine translations, namely whether the noisy phenomena are kept in the translations, corrected, or caused errors. The analysed data consists of English user reviews of Amazon products translated into Croatian, Russian and Finnish by professional translators, translation students, machine translation (MT) systems, and ChatGPT language model. The results show that overall, ChatGPT and professional translators mostly correct/standardise those parts, while students are often keeping them. Furthermore, MT systems are most prone to errors while ChatGPT is more robust, but notably less robust than human translators. Finally, some of the phenomena are particularly challenging both for MT systems and for ChatGPT, especially spelling errors and informal constructions.

2023

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Proceedings of the 24th Annual Conference of the European Association for Machine Translation
Mary Nurminen | Judith Brenner | Maarit Koponen | Sirkku Latomaa | Mikhail Mikhailov | Frederike Schierl | Tharindu Ranasinghe | Eva Vanmassenhove | Sergi Alvarez Vidal | Nora Aranberri | Mara Nunziatini | Carla Parra Escartín | Mikel Forcada | Maja Popovic | Carolina Scarton | Helena Moniz
Proceedings of the 24th Annual Conference of the European Association for Machine Translation

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Computational analysis of different translations: by professionals, students and machines
Maja Popovic | Ekaterina Lapshinova-Koltunski | Maarit Koponen
Proceedings of the 24th Annual Conference of the European Association for Machine Translation

In this work, we analyse different translated texts in terms of various text features. We compare two types of human translations, professional and students’, and machine translation outputs in terms of lexical and grammatical variety, sentence length,as well as frequencies of different POS tags and POS-trigrams. Our experimentsare carried out on parallel translations into three languages, Croatian, Finnish andRussian, all originating from the same source English texts. Our results indicatethat machine translations are closest to the source text, followed by student translations. Also, student translations are similar both to professional as well as to MT, sometimes even more to MT. Furthermore, we identify sets of features which are convenient for distinguishing machine from human translations.

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Using MT for multilingual covid-19 case load prediction from social media texts
Maja Popovic | Vasudevan Nedumpozhimana | Meegan Gower | Sneha Rautmare | Nishtha Jain | John Kelleher
Proceedings of the 24th Annual Conference of the European Association for Machine Translation

In the context of an epidemiological study involving multilingual social media, this paper reports on the ability of machine translation systems to preserve content relevant for a document classification task designed to determine whether the social media text is related to covid. The results indicate that machine translation does provide a feasible basis for scaling epidemiological social media surveillance to multiple languages. Moreover, a qualitative error analysis revealed that the majority of classification errors are not caused by MT errors.

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Exploring Variation of Results from Different Experimental Conditions
Maja Popović | Mohammad Arvan | Natalie Parde | Anya Belz
Findings of the Association for Computational Linguistics: ACL 2023

It might reasonably be expected that running multiple experiments for the same task using the same data and model would yield very similar results. Recent research has, however, shown this not to be the case for many NLP experiments. In this paper, we report extensive coordinated work by two NLP groups to run the training and testing pipeline for three neural text simplification models under varying experimental conditions, including different random seeds, run-time environments, and dependency versions, yielding a large number of results for each of the three models using the same data and train/dev/test set splits. From one perspective, these results can be interpreted as shedding light on the reproducibility of evaluation results for the three NTS models, and we present an in-depth analysis of the variation observed for different combinations of experimental conditions. From another perspective, the results raise the question of whether the averaged score should be considered the ‘true’ result for each model.

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Proceedings of the 3rd Workshop on Human Evaluation of NLP Systems
Anya Belz | Maja Popović | Ehud Reiter | Craig Thomson | João Sedoc
Proceedings of the 3rd Workshop on Human Evaluation of NLP Systems

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Findings of the 2023 Conference on Machine Translation (WMT23): LLMs Are Here but Not Quite There Yet
Tom Kocmi | Eleftherios Avramidis | Rachel Bawden | Ondřej Bojar | Anton Dvorkovich | Christian Federmann | Mark Fishel | Markus Freitag | Thamme Gowda | Roman Grundkiewicz | Barry Haddow | Philipp Koehn | Benjamin Marie | Christof Monz | Makoto Morishita | Kenton Murray | Makoto Nagata | Toshiaki Nakazawa | Martin Popel | Maja Popović | Mariya Shmatova
Proceedings of the Eighth Conference on Machine Translation

This paper presents the results of the General Machine Translation Task organised as part of the 2023 Conference on Machine Translation (WMT). In the general MT task, participants were asked to build machine translation systems for any of 8 language pairs (corresponding to 14 translation directions), to be evaluated on test sets consisting of up to four different domains. We evaluate system outputs with professional human annotators using a combination of source-based Direct Assessment and scalar quality metric (DA+SQM).

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Medical Concept Mention Identification in Social Media Posts Using a Small Number of Sample References
Vasudevan Nedumpozhimana | Sneha Rautmare | Meegan Gower | Nishtha Jain | Maja Popović | Patricia Buffini | John Kelleher
Proceedings of the 14th International Conference on Recent Advances in Natural Language Processing

Identification of mentions of medical concepts in social media text can provide useful information for caseload prediction of diseases like Covid-19 and Measles. We propose a simple model for the automatic identification of the medical concept mentions in the social media text. We validate the effectiveness of the proposed model on Twitter, Reddit, and News/Media datasets.

2022

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A General Framework for Detecting Metaphorical Collocations
Marija Brkić Bakarić | Lucia Načinović Prskalo | Maja Popović
Proceedings of the 18th Workshop on Multiword Expressions @LREC2022

This paper aims at identifying a specific set of collocations known under the term metaphorical collocations. In this type of collocations, a semantic shift has taken place in one of the components. Since the appropriate gold standard needs to be compiled prior to any serious endeavour to extract metaphorical collocations automatically, this paper first presents the steps taken to compile it, and then establishes appropriate evaluation framework. The process of compiling the gold standard is illustrated on one of the most frequent Croatian nouns, which resulted in the preliminary relation significance set. With the aim to investigate the possibility of facilitating the process, frequency, logDice, relation, and pretrained word embeddings are used as features in the classification task conducted on the logDice-based word sketch relation lists. Preliminary results are presented.

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On reporting scores and agreement for error annotation tasks
Maja Popović | Anya Belz
Proceedings of the 2nd Workshop on Natural Language Generation, Evaluation, and Metrics (GEM)

This work examines different ways of aggregating scores for error annotation in MT outputs: raw error counts, error counts normalised over total number of words (word percentage’), and error counts normalised over total number of errors (error percentage’). We use each of these three scores to calculate inter-annotator agreement in the form of Krippendorff’s alpha and Pearson’s r and compare the obtained numbers, overall and separately for different types of errors. While each score has its advantages depending on the goal of the evaluation, we argue that the best way of estimating inter-annotator agreement using such numbers are raw counts. If the annotation process ensures that the total number of words cannot differ among the annotators (for example, due to adding omission symbols), normalising over number of words will lead to the same conclusions. In contrast, total number of errors is very subjective because different annotators often perceive different amount of errors in the same text, therefore normalising over this number can indicate lower agreements.

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DiHuTra: a Parallel Corpus to Analyse Differences between Human Translations
Ekaterina Lapshinova-Koltunski | Maja Popović | Maarit Koponen
Proceedings of the Thirteenth Language Resources and Evaluation Conference

This paper describes a new corpus of human translations which contains both professional and students translations. The data consists of English sources – texts from news and reviews – and their translations into Russian and Croatian, as well as of the subcorpus containing translations of the review texts into Finnish. All target languages represent mid-resourced and less or mid-investigated ones. The corpus will be valuable for studying variation in translation as it allows a direct comparison between human translations of the same source texts. The corpus will also be a valuable resource for evaluating machine translation systems. We believe that this resource will facilitate understanding and improvement of the quality issues in both human and machine translation. In the paper, we describe how the data was collected, provide information on translator groups and summarise the differences between the human translations at hand based on our preliminary results with shallow features.

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Leveraging Pre-trained Language Models for Gender Debiasing
Nishtha Jain | Declan Groves | Lucia Specia | Maja Popović
Proceedings of the Thirteenth Language Resources and Evaluation Conference

Studying and mitigating gender and other biases in natural language have become important areas of research from both algorithmic and data perspectives. This paper explores the idea of reducing gender bias in a language generation context by generating gender variants of sentences. Previous work in this field has either been rule-based or required large amounts of gender balanced training data. These approaches are however not scalable across multiple languages, as creating data or rules for each language is costly and time-consuming. This work explores a light-weight method to generate gender variants for a given text using pre-trained language models as the resource, without any task-specific labelled data. The approach is designed to work on multiple languages with minimal changes in the form of heuristics. To showcase that, we have tested it on a high-resourced language, namely Spanish, and a low-resourced language from a different family, namely Serbian. The approach proved to work very well on Spanish, and while the results were less positive for Serbian, it showed potential even for languages where pre-trained models are less effective.

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The 2022 ReproGen Shared Task on Reproducibility of Evaluations in NLG: Overview and Results
Anya Belz | Anastasia Shimorina | Maja Popović | Ehud Reiter
Proceedings of the 15th International Conference on Natural Language Generation: Generation Challenges

Against a background of growing interest in reproducibility in NLP and ML, and as part of an ongoing research programme designed to develop theory and practice of reproducibility assessment in NLP, we organised the second shared task on reproducibility of evaluations in NLG, ReproGen 2022. This paper describes the shared task, summarises results from the reproduction studies submitted, and provides further comparative analysis of the results. Out of six initial team registrations, we received submissions from five teams. Meta-analysis of the five reproduction studies revealed varying degrees of reproducibility, and allowed further tentative conclusions about what types of evaluation tend to have better reproducibility.

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Reproducing a Manual Evaluation of the Simplicity of Text Simplification System Outputs
Maja Popović | Sheila Castilho | Rudali Huidrom | Anya Belz
Proceedings of the 15th International Conference on Natural Language Generation: Generation Challenges

In this paper we describe our reproduction study of the human evaluation of text simplic- ity reported by Nisioi et al. (2017). The work was carried out as part of the ReproGen Shared Task 2022 on Reproducibility of Evaluations in NLG. Our aim was to repeat the evaluation of simplicity for nine automatic text simplification systems with a different set of evaluators. We describe our experimental design together with the known aspects of the original experimental design and present the results from both studies. Pearson correlation between the original and reproduction scores is moderate to high (0.776). Inter-annotator agreement in the reproduction study is lower (0.40) than in the original study (0.66). We discuss challenges arising from the unavailability of certain aspects of the origi- nal set-up, and make several suggestions as to how reproduction of similar evaluations can be made easier in future.

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DiHuTra: a Parallel Corpus to Analyse Differences between Human Translations
Ekaterina Lapshinova-Koltunski | Maja Popović | Maarit Koponen
Proceedings of the 23rd Annual Conference of the European Association for Machine Translation

This project aimed to design a corpus of parallel human translations (HTs) of the same source texts by professionals and students. The resulting corpus consists of English news and reviews source texts, their translations into Russian and Croatian, and translations of the reviews into Finnish. The corpus will be valuable for both studying variation in translation and evaluating machine translation (MT) systems.

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Findings of the 2022 Conference on Machine Translation (WMT22)
Tom Kocmi | Rachel Bawden | Ondřej Bojar | Anton Dvorkovich | Christian Federmann | Mark Fishel | Thamme Gowda | Yvette Graham | Roman Grundkiewicz | Barry Haddow | Rebecca Knowles | Philipp Koehn | Christof Monz | Makoto Morishita | Masaaki Nagata | Toshiaki Nakazawa | Michal Novák | Martin Popel | Maja Popović
Proceedings of the Seventh Conference on Machine Translation (WMT)

This paper presents the results of the General Machine Translation Task organised as part of the Conference on Machine Translation (WMT) 2022. In the general MT task, participants were asked to build machine translation systems for any of 11 language pairs, to be evaluated on test sets consisting of four different domains. We evaluate system outputs with human annotators using two different techniques: reference-based direct assessment and (DA) and a combination of DA and scalar quality metric (DA+SQM).

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Proceedings of the 2nd Workshop on Human Evaluation of NLP Systems (HumEval)
Anya Belz | Maja Popović | Ehud Reiter | Anastasia Shimorina
Proceedings of the 2nd Workshop on Human Evaluation of NLP Systems (HumEval)

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Quantified Reproducibility Assessment of NLP Results
Anya Belz | Maja Popovic | Simon Mille
Proceedings of the 60th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)

This paper describes and tests a method for carrying out quantified reproducibility assessment (QRA) that is based on concepts and definitions from metrology. QRA produces a single score estimating the degree of reproducibility of a given system and evaluation measure, on the basis of the scores from, and differences between, different reproductions. We test QRA on 18 different system and evaluation measure combinations (involving diverse NLP tasks and types of evaluation), for each of which we have the original results and one to seven reproduction results. The proposed QRA method produces degree-of-reproducibility scores that are comparable across multiple reproductions not only of the same, but also of different, original studies. We find that the proposed method facilitates insights into causes of variation between reproductions, and as a result, allows conclusions to be drawn about what aspects of system and/or evaluation design need to be changed in order to improve reproducibility.

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Building Machine Translation System for Software Product Descriptions Using Domain-specific Sub-corpora Extraction
Pintu Lohar | Sinead Madden | Edmond O’Connor | Maja Popovic | Tanya Habruseva
Proceedings of the 15th biennial conference of the Association for Machine Translation in the Americas (Volume 1: Research Track)

Building Machine Translation systems for a specific domain requires a sufficiently large and good quality parallel corpus in that domain. However, this is a bit challenging task due to the lack of parallel data in many domains such as economics, science and technology, sports etc. In this work, we build English-to-French translation systems for software product descriptions scraped from LinkedIn website. Moreover, we developed a first-ever test parallel data set of product descriptions. We conduct experiments by building a baseline translation system trained on general domain and then domain-adapted systems using sentence-embedding based corpus filtering and domain-specific sub-corpora extraction. All the systems are tested on our newly developed data set mentioned earlier. Our experimental evaluation reveals that the domain-adapted model based on our proposed approaches outperforms the baseline.

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Proceedings of the 15th biennial conference of the Association for Machine Translation in the Americas (Workshop 2: Corpus Generation and Corpus Augmentation for Machine Translation)
John E. Ortega | Marine Carpuat | William Chen | Katharina Kann | Constantine Lignos | Maja Popovic | Shabnam Tafreshi
Proceedings of the 15th biennial conference of the Association for Machine Translation in the Americas (Workshop 2: Corpus Generation and Corpus Augmentation for Machine Translation)

2021

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On nature and causes of observed MT errors
Maja Popovic
Proceedings of Machine Translation Summit XVIII: Research Track

This work describes analysis of nature and causes of MT errors observed by different evaluators under guidance of different quality criteria: adequacy and comprehension and and a not specified generic mixture of adequacy and fluency. We report results for three language pairs and two domains and eleven MT systems. Our findings indicate that and despite the fact that some of the identified phenomena depend on domain and/or language and the following set of phenomena can be considered as generally challenging for modern MT systems: rephrasing groups of words and translation of ambiguous source words and translating noun phrases and and mistranslations. Furthermore and we show that the quality criterion also has impact on error perception. Our findings indicate that comprehension and adequacy can be assessed simultaneously by different evaluators and so that comprehension and as an important quality criterion and can be included more often in human evaluations.

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Agree to Disagree: Analysis of Inter-Annotator Disagreements in Human Evaluation of Machine Translation Output
Maja Popović
Proceedings of the 25th Conference on Computational Natural Language Learning

This work describes an analysis of inter-annotator disagreements in human evaluation of machine translation output. The errors in the analysed texts were marked by multiple annotators under guidance of different quality criteria: adequacy, comprehension, and an unspecified generic mixture of adequacy and fluency. Our results show that different criteria result in different disagreements, and indicate that a clear definition of quality criterion can improve the inter-annotator agreement. Furthermore, our results show that for certain linguistic phenomena which are not limited to one or two words (such as word ambiguity or gender) but span over several words or even entire phrases (such as negation or relative clause), disagreements do not necessarily represent “errors” or “noise” but are rather inherent to the evaluation process. %These disagreements are caused by differences in error perception and/or the fact that there is no single correct translation of a text so that multiple solutions are possible. On the other hand, for some other phenomena (such as omission or verb forms) agreement can be easily improved by providing more precise and detailed instructions to the evaluators.

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On Machine Translation of User Reviews
Maja Popović | Alberto Poncelas | Marija Brkic | Andy Way
Proceedings of the International Conference on Recent Advances in Natural Language Processing (RANLP 2021)

This work investigates neural machine translation (NMT) systems for translating English user reviews into Croatian and Serbian, two similar morphologically complex languages. Two types of reviews are used for testing the systems: IMDb movie reviews and Amazon product reviews. Two types of training data are explored: large out-of-domain bilingual parallel corpora, as well as small synthetic in-domain parallel corpus obtained by machine translation of monolingual English Amazon reviews into the target languages. Both automatic scores and human evaluation show that using the synthetic in-domain corpus together with a selected sub-set of out-of-domain data is the best option. Separated results on IMDb and Amazon reviews indicate that MT systems perform differently on different review types so that user reviews generally should not be considered as a homogeneous genre. Nevertheless, more detailed research on larger amount of different reviews covering different domains/topics is needed to fully understand these differences.

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Generating Gender Augmented Data for NLP
Nishtha Jain | Maja Popović | Declan Groves | Eva Vanmassenhove
Proceedings of the 3rd Workshop on Gender Bias in Natural Language Processing

Gender bias is a frequent occurrence in NLP-based applications, especially pronounced in gender-inflected languages. Bias can appear through associations of certain adjectives and animate nouns with the natural gender of referents, but also due to unbalanced grammatical gender frequencies of inflected words. This type of bias becomes more evident in generating conversational utterances where gender is not specified within the sentence, because most current NLP applications still work on a sentence-level context. As a step towards more inclusive NLP, this paper proposes an automatic and generalisable re-writing approach for short conversational sentences. The rewriting method can be applied to sentences that, without extra-sentential context, have multiple equivalent alternatives in terms of gender. The method can be applied both for creating gender balanced outputs as well as for creating gender balanced training data. The proposed approach is based on a neural machine translation system trained to ‘translate’ from one gender alternative to another. Both the automatic and manual analysis of the approach show promising results with respect to the automatic generation of gender alternatives for conversational sentences in Spanish.

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A Reproduction Study of an Annotation-based Human Evaluation of MT Outputs
Maja Popović | Anya Belz
Proceedings of the 14th International Conference on Natural Language Generation

In this paper we report our reproduction study of the Croatian part of an annotation-based human evaluation of machine-translated user reviews (Popovic, 2020). The work was carried out as part of the ReproGen Shared Task on Reproducibility of Human Evaluation in NLG. Our aim was to repeat the original study exactly, except for using a different set of evaluators. We describe the experimental design, characterise differences between original and reproduction study, and present the results from each study, along with analysis of the similarity between them. For the six main evaluation results of Major/Minor/All Comprehension error rates and Major/Minor/All Adequacy error rates, we find that (i) 4/6 system rankings are the same in both studies, (ii) the relative differences between systems are replicated well for Major Comprehension and Adequacy (Pearson’s > 0.9), but not for the corresponding Minor error rates (Pearson’s 0.36 for Adequacy, 0.67 for Comprehension), and (iii) the individual system scores for both types of Minor error rates had a higher degree of reproducibility than the corresponding Major error rates. We also examine inter-annotator agreement and compare the annotations obtained in the original and reproduction studies.

2020

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On Context Span Needed for Machine Translation Evaluation
Sheila Castilho | Maja Popović | Andy Way
Proceedings of the Twelfth Language Resources and Evaluation Conference

Despite increasing efforts to improve evaluation of machine translation (MT) by going beyond the sentence level to the document level, the definition of what exactly constitutes a “document level” is still not clear. This work deals with the context span necessary for a more reliable MT evaluation. We report results from a series of surveys involving three domains and 18 target languages designed to identify the necessary context span as well as issues related to it. Our findings indicate that, despite the fact that some issues and spans are strongly dependent on domain and on the target language, a number of common patterns can be observed so that general guidelines for context-aware MT evaluation can be drawn.

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Neural Machine Translation for translating into Croatian and Serbian
Maja Popović | Alberto Poncelas | Marija Brkic | Andy Way
Proceedings of the 7th Workshop on NLP for Similar Languages, Varieties and Dialects

In this work, we systematically investigate different set-ups for training of neural machine translation (NMT) systems for translation into Croatian and Serbian, two closely related South Slavic languages. We explore English and German as source languages, different sizes and types of training corpora, as well as bilingual and multilingual systems. We also explore translation of English IMDb user movie reviews, a domain/genre where only monolingual data are available. First, our results confirm that multilingual systems with joint target languages perform better. Furthermore, translation performance from English is much better than from German, partly because German is morphologically more complex and partly because the corpus consists mostly of parallel human translations instead of original text and its human translation. The translation from German should be further investigated systematically. For translating user reviews, creating synthetic in-domain parallel data through back- and forward-translation and adding them to a small out-of-domain parallel corpus can yield performance comparable with a system trained on a full out-of-domain corpus. However, it is still not clear what is the optimal size of synthetic in-domain data, especially for forward-translated data where the target language is machine translated. More detailed research including manual evaluation and analysis is needed in this direction.

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Neural Machine Translation between similar South-Slavic languages
Maja Popović | Alberto Poncelas
Proceedings of the Fifth Conference on Machine Translation

This paper describes the ADAPT-DCU machine translation systems built for the WMT 2020 shared task on Similar Language Translation. We explored several set-ups for NMT for Croatian–Slovenian and Serbian–Slovenian language pairs in both translation directions. Our experiments focus on different amounts and types of training data: we first apply basic filtering on the OpenSubtitles training corpora, then we perform additional cleaning of remaining misaligned segments based on character n-gram matching. Finally, we make use of additional monolingual data by creating synthetic parallel data through back-translation. Automatic evaluation shows that multilingual systems with joint Serbian and Croatian data are better than bilingual, as well as that character-based cleaning leads to improved scores while using less data. The results also confirm once more that adding back-translated data further improves the performance, especially when the synthetic data is similar to the desired domain of the development and test set. This, however, might come at a price of prolonged training time, especially for multitarget systems.

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Informative Manual Evaluation of Machine Translation Output
Maja Popović
Proceedings of the 28th International Conference on Computational Linguistics

This work proposes a new method for manual evaluation of Machine Translation (MT) output based on marking actual issues in the translated text. The novelty is that the evaluators are not assigning any scores, nor classifying errors, but marking all problematic parts (words, phrases, sentences) of the translation. The main advantage of this method is that the resulting annotations do not only provide overall scores by counting words with assigned tags, but can be further used for analysis of errors and challenging linguistic phenomena, as well as inter-annotator disagreements. Detailed analysis and understanding of actual problems are not enabled by typical manual evaluations where the annotators are asked to assign overall scores or to rank two or more translations. The proposed method is very general: it can be applied on any genre/domain and language pair, and it can be guided by various types of quality criteria. Also, it is not restricted to MT output, but can be used for other types of generated text.

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Proceedings of 1st Workshop on Post-Editing in Modern-Day Translation
John E. Ortega | Marcello Federico | Constantin Orasan | Maja Popovic
Proceedings of 1st Workshop on Post-Editing in Modern-Day Translation

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Relations between comprehensibility and adequacy errors in machine translation output
Maja Popović
Proceedings of the 24th Conference on Computational Natural Language Learning

This work presents a detailed analysis of translation errors perceived by readers as comprehensibility and/or adequacy issues. The main finding is that good comprehensibility, similarly to good fluency, can mask a number of adequacy errors. Of all major adequacy errors, 30% were fully comprehensible, thus fully misleading the reader to accept the incorrect information. Another 25% of major adequacy errors were perceived as almost comprehensible, thus being potentially misleading. Also, a vast majority of omissions (about 70%) is hidden by comprehensibility. Further analysis of misleading translations revealed that the most frequent error types are ambiguity, mistranslation, noun phrase error, word-by-word translation, untranslated word, subject-verb agreement, and spelling error in the source text. However, none of these error types appears exclusively in misleading translations, but are also frequent in fully incorrect (incomprehensible inadequate) and discarded correct (incomprehensible adequate) translations. Deeper analysis is needed to potentially detect underlying phenomena specifically related to misleading translations.

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On the differences between human translations
Maja Popovic
Proceedings of the 22nd Annual Conference of the European Association for Machine Translation

Many studies have confirmed that translated texts exhibit different features than texts originally written in the given language. This work explores texts translated by different translators taking into account expertise and native language. A set of computational analyses was conducted on three language pairs, English-Croatian, German-French and English-Finnish, and the results show that each of the factors has certain influence on the features of the translated texts, especially on sentence length and lexical richness. The results also indicate that for translations used for machine translation evaluation, it is important to specify these factors, especially if comparing machine translation quality with human translation quality is involved.

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QRev: Machine Translation of User Reviews: What Influences the Translation Quality?
Maja Popovic
Proceedings of the 22nd Annual Conference of the European Association for Machine Translation

This project aims to identify the important aspects of translation quality of user reviews which will represent a starting point for developing better automatic MT metrics and challenge test sets, and will be also helpful for developing MT systems for this genre. We work on two types of reviews: Amazon products and IMDb movies, written in English and translated into two closely related target languages, Croatian and Serbian.

2019

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Combining PBSMT and NMT Back-translated Data for Efficient NMT
Alberto Poncelas | Maja Popović | Dimitar Shterionov | Gideon Maillette de Buy Wenniger | Andy Way
Proceedings of the International Conference on Recent Advances in Natural Language Processing (RANLP 2019)

Neural Machine Translation (NMT) models achieve their best performance when large sets of parallel data are used for training. Consequently, techniques for augmenting the training set have become popular recently. One of these methods is back-translation, which consists on generating synthetic sentences by translating a set of monolingual, target-language sentences using a Machine Translation (MT) model. Generally, NMT models are used for back-translation. In this work, we analyze the performance of models when the training data is extended with synthetic data using different MT approaches. In particular we investigate back-translated data generated not only by NMT but also by Statistical Machine Translation (SMT) models and combinations of both. The results reveal that the models achieve the best performances when the training set is augmented with back-translated data created by merging different MT approaches.

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Are ambiguous conjunctions problematic for machine translation?
Maja Popović | Sheila Castilho
Proceedings of the International Conference on Recent Advances in Natural Language Processing (RANLP 2019)

The translation of ambiguous words still poses challenges for machine translation. In this work, we carry out a systematic quantitative analysis regarding the ability of different machine translation systems to disambiguate the source language conjunctions “but” and “and”. We evaluate specialised test sets focused on the translation of these two conjunctions. The test sets contain source languages that do not distinguish different variants of the given conjunction, whereas the target languages do. In total, we evaluate the conjunction “but” on 20 translation outputs, and the conjunction “and” on 10. All machine translation systems almost perfectly recognise one variant of the target conjunction, especially for the source conjunction “but”. The other target variant, however, represents a challenge for machine translation systems, with accuracy varying from 50% to 95% for “but” and from 20% to 57% for “and”. The major error for all systems is replacing the correct target variant with the opposite one.

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Automated Text Simplification as a Preprocessing Step for Machine Translation into an Under-resourced Language
Sanja Štajner | Maja Popović
Proceedings of the International Conference on Recent Advances in Natural Language Processing (RANLP 2019)

In this work, we investigate the possibility of using fully automatic text simplification system on the English source in machine translation (MT) for improving its translation into an under-resourced language. We use the state-of-the-art automatic text simplification (ATS) system for lexically and syntactically simplifying source sentences, which are then translated with two state-of-the-art English-to-Serbian MT systems, the phrase-based MT (PBMT) and the neural MT (NMT). We explore three different scenarios for using the ATS in MT: (1) using the raw output of the ATS; (2) automatically filtering out the sentences with low grammaticality and meaning preservation scores; and (3) performing a minimal manual correction of the ATS output. Our results show improvement in fluency of the translation regardless of the chosen scenario, and difference in success of the three scenarios depending on the MT approach used (PBMT or NMT) with regards to improving translation fluency and post-editing effort.

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Building English-to-Serbian Machine Translation System for IMDb Movie Reviews
Pintu Lohar | Maja Popović | Andy Way
Proceedings of the 7th Workshop on Balto-Slavic Natural Language Processing

This paper reports the results of the first experiment dealing with the challenges of building a machine translation system for user-generated content involving a complex South Slavic language. We focus on translation of English IMDb user movie reviews into Serbian, in a low-resource scenario. We explore potentials and limits of (i) phrase-based and neural machine translation systems trained on out-of-domain clean parallel data from news articles (ii) creating additional synthetic in-domain parallel corpus by machine-translating the English IMDb corpus into Serbian. Our main findings are that morphology and syntax are better handled by the neural approach than by the phrase-based approach even in this low-resource mismatched domain scenario, however the situation is different for the lexical aspect, especially for person names. This finding also indicates that in general, machine translation of person names into Slavic languages (especially those which require/allow transcription) should be investigated more systematically.

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Evaluating Conjunction Disambiguation on English-to-German and French-to-German WMT 2019 Translation Hypotheses
Maja Popović
Proceedings of the Fourth Conference on Machine Translation (Volume 2: Shared Task Papers, Day 1)

We present a test set for evaluating an MT system’s capability to translate ambiguous conjunctions depending on the sentence structure. We concentrate on the English conjunction “but” and its French equivalent “mais” which can be translated into two different German conjunctions. We evaluate all English-to-German and French-to-German submissions to the WMT 2019 shared translation task. The evaluation is done mainly automatically, with additional fast manual inspection of unclear cases. All systems almost perfectly recognise the target conjunction “aber”, whereas accuracies for the other target conjunction “sondern” range from 78% to 97%, and the errors are mostly caused by replacing it with the alternative conjunction “aber”. The best performing system for both language pairs is a multilingual Transformer “TartuNLP” system trained on all WMT 2019 language pairs which use the Latin script, indicating that the multilingual approach is beneficial for conjunction disambiguation. As for other system features, such as using synthetic back-translated data, context-aware, hybrid, etc., no particular (dis)advantages can be observed. Qualitative manual inspection of translation hypotheses shown that highly ranked systems generally produce translations with high adequacy and fluency, meaning that these systems are not only capable of capturing the right conjunction whereas the rest of the translation hypothesis is poor. On the other hand, the low ranked systems generally exhibit lower fluency and poor adequacy.

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Automatic error classification with multiple error labels
Maja Popovic | David Vilar
Proceedings of Machine Translation Summit XVII: Research Track

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On reducing translation shifts in translations intended for MT evaluation
Maja Popovic
Proceedings of Machine Translation Summit XVII: Translator, Project and User Tracks

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Proceedings of the Qualities of Literary Machine Translation
James Hadley | Maja Popović | Haithem Afli | Andy Way
Proceedings of the Qualities of Literary Machine Translation

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Challenge Test Sets for MT Evaluation
Maja Popović | Sheila Castilho
Proceedings of Machine Translation Summit XVII: Tutorial Abstracts

Most of the test sets used for the evaluation of MT systems reflect the frequency distribution of different phenomena found in naturally occurring data (”standard” or ”natural” test sets). However, to better understand particular strengths and weaknesses of MT systems, especially those based on neural networks, it is necessary to apply more focused evaluation procedures. Therefore, another type of test sets (”challenge” test sets, also called ”test suites”) is being increasingly employed in order to highlight points of difficulty which are relevant to model development, training, or using of the given system. This tutorial will be useful for anyone (researchers, developers, users, translators) interested in detailed evaluation and getting a better understanding of machine translation (MT) systems and models. The attendees will learn about the motivation and linguistic background of challenge test sets and a range of testing possibilities applied to the state-of-the-art MT systems, as well as a number of practical aspects and challenges.

2018

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A Multilingual Wikified Data Set of Educational Material
Iris Hendrickx | Eirini Takoulidou | Thanasis Naskos | Katia Lida Kermanidis | Vilelmini Sosoni | Hugo de Vos | Maria Stasimioti | Menno van Zaanen | Panayota Georgakopoulou | Valia Kordoni | Maja Popovic | Markus Egg | Antal van den Bosch
Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)

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Complex Word Identification Using Character n-grams
Maja Popović
Proceedings of the Thirteenth Workshop on Innovative Use of NLP for Building Educational Applications

This paper investigates the use of character n-gram frequencies for identifying complex words in English, German and Spanish texts. The approach is based on the assumption that complex words are likely to contain different character sequences than simple words. The multinomial Naive Bayes classifier was used with n-grams of different lengths as features, and the best results were obtained for the combination of 2-grams and 4-grams. This variant was submitted to the Complex Word Identification Shared Task 2018 for all texts and achieved F-scores between 70% and 83%. The system was ranked in the middle range for all English texts, as third of fourteen submissions for German, and as tenth of seventeen submissions for Spanish. The method is not very convenient for the cross-language task, achieving only 59% on the French text.

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Improving Machine Translation of English Relative Clauses with Automatic Text Simplification
Sanja Štajner | Maja Popović
Proceedings of the 1st Workshop on Automatic Text Adaptation (ATA)

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Proceedings of the 21st Annual Conference of the European Association for Machine Translation
Juan Antonio Pérez-Ortiz | Felipe Sánchez-Martínez | Miquel Esplà-Gomis | Maja Popović | Celia Rico | André Martins | Joachim Van den Bogaert | Mikel L. Forcada
Proceedings of the 21st Annual Conference of the European Association for Machine Translation

2017

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chrF++: words helping character n-grams
Maja Popović
Proceedings of the Second Conference on Machine Translation

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Proceedings of the 55th Annual Meeting of the Association for Computational Linguistics: Tutorial Abstracts
Maja Popović | Jordan Boyd-Graber
Proceedings of the 55th Annual Meeting of the Association for Computational Linguistics: Tutorial Abstracts

2016

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TraMOOC (Translation for Massive Open Online Courses): providing reliable MT for MOOCs
Valia Kordoni | Lexi Birch | Ioana Buliga | Kostadin Cholakov | Markus Egg | Federico Gaspari | Yota Georgakopolou | Maria Gialama | Iris Hendrickx | Mitja Jermol | Katia Kermanidis | Joss Moorkens | Davor Orlic | Michael Papadopoulos | Maja Popović | Rico Sennrich | Vilelmini Sosoni | Dimitrios Tsoumakos | Antal van den Bosch | Menno van Zaanen | Andy Way
Proceedings of the 19th Annual Conference of the European Association for Machine Translation: Projects/Products

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PE2rr Corpus: Manual Error Annotation of Automatically Pre-annotated MT Post-edits
Maja Popović | Mihael Arčan
Proceedings of the Tenth International Conference on Language Resources and Evaluation (LREC'16)

We present a freely available corpus containing source language texts from different domains along with their automatically generated translations into several distinct morphologically rich languages, their post-edited versions, and error annotations of the performed post-edit operations. We believe that the corpus will be useful for many different applications. The main advantage of the approach used for creation of the corpus is the fusion of post-editing and error classification tasks, which have usually been seen as two independent tasks, although naturally they are not. We also show benefits of coupling automatic and manual error classification which facilitates the complex manual error annotation task as well as the development of automatic error classification tools. In addition, the approach facilitates annotation of language pair related issues.

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Tools and Guidelines for Principled Machine Translation Development
Nora Aranberri | Eleftherios Avramidis | Aljoscha Burchardt | Ondřej Klejch | Martin Popel | Maja Popović
Proceedings of the Tenth International Conference on Language Resources and Evaluation (LREC'16)

This work addresses the need to aid Machine Translation (MT) development cycles with a complete workflow of MT evaluation methods. Our aim is to assess, compare and improve MT system variants. We hereby report on novel tools and practices that support various measures, developed in order to support a principled and informed approach of MT development. Our toolkit for automatic evaluation showcases quick and detailed comparison of MT system variants through automatic metrics and n-gram feedback, along with manual evaluation via edit-distance, error annotation and task-based feedback.

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chrF deconstructed: beta parameters and n-gram weights
Maja Popović
Proceedings of the First Conference on Machine Translation: Volume 2, Shared Task Papers

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Potential and Limits of Using Post-edits as Reference Translations for MT Evaluation
Maja Popovic | Mihael Arčan | Arle Lommel
Proceedings of the 19th Annual Conference of the European Association for Machine Translation

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Can Text Simplification Help Machine Translation?
Sanja Štajner | Maja Popovic
Proceedings of the 19th Annual Conference of the European Association for Machine Translation

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Language Related Issues for Machine Translation between Closely Related South Slavic Languages
Maja Popović | Mihael Arčan | Filip Klubička
Proceedings of the Third Workshop on NLP for Similar Languages, Varieties and Dialects (VarDial3)

Machine translation between closely related languages is less challenging and exibits a smaller number of translation errors than translation between distant languages, but there are still obstacles which should be addressed in order to improve such systems. This work explores the obstacles for machine translation systems between closely related South Slavic languages, namely Croatian, Serbian and Slovenian. Statistical systems for all language pairs and translation directions are trained using parallel texts from different domains, however mainly on spoken language i.e. subtitles. For translation between Serbian and Croatian, a rule-based system is also explored. It is shown that for all language pairs and translation systems, the main obstacles are differences between structural properties.

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Enlarging Scarce In-domain English-Croatian Corpus for SMT of MOOCs Using Serbian
Maja Popović | Kostadin Cholakov | Valia Kordoni | Nikola Ljubešić
Proceedings of the Third Workshop on NLP for Similar Languages, Varieties and Dialects (VarDial3)

Massive Open Online Courses have been growing rapidly in size and impact. Yet the language barrier constitutes a major growth impediment in reaching out all people and educating all citizens. A vast majority of educational material is available only in English, and state-of-the-art machine translation systems still have not been tailored for this peculiar genre. In addition, a mere collection of appropriate in-domain training material is a challenging task. In this work, we investigate statistical machine translation of lecture subtitles from English into Croatian, which is morphologically rich and generally weakly supported, especially for the educational domain. We show that results comparable with publicly available systems trained on much larger data can be achieved if a small in-domain training set is used in combination with additional in-domain corpus originating from the closely related Serbian language.

2015

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DFKI’s experimental hybrid MT system for WMT 2015
Eleftherios Avramidis | Maja Popović | Aljoscha Burchardt
Proceedings of the Tenth Workshop on Statistical Machine Translation

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chrF: character n-gram F-score for automatic MT evaluation
Maja Popović
Proceedings of the Tenth Workshop on Statistical Machine Translation

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Identifying main obstacles for statistical machine translation of morphologically rich South Slavic languages
Maja Popović | Mihael Arčan
Proceedings of the 18th Annual Conference of the European Association for Machine Translation

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Poor man’s lemmatisation for automatic error classification
Maja Popović | Mihael Arčan | Eleftherios Avramidis | Aljoscha Burchardt | Arle Lommel
Proceedings of the 18th Annual Conference of the European Association for Machine Translation

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Towards Deeper MT - A Hybrid System for German
Eleftherios Avramidis | Aljoscha Burchardt | Maja Popović | Hans Uszkoreit
Proceedings of the 1st Deep Machine Translation Workshop

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Identifying main obstacles for statistical machine translation of morphologically rich South Slavic languages
Maja Popovic | Mihael Arcan
Proceedings of the 18th Annual Conference of the European Association for Machine Translation

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Poor man’s lemmatisation for automatic error classification
Maja Popovic | Mihael Arcan | Eleftherios Avramidis | Aljoscha Burchardt
Proceedings of the 18th Annual Conference of the European Association for Machine Translation

2014

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Using a new analytic measure for the annotation and analysis of MT errors on real data
Arle Lommel | Aljoscha Burchardt | Maja Popović | Kim Harris | Eleftherios Avramidis | Hans Uszkoreit
Proceedings of the 17th Annual Conference of the European Association for Machine Translation

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Relations between different types of post-editing operations, cognitive effort and temporal effort
Maja Popović | Arle Lommel | Aljoscha Burchardt | Eleftherios Avramidis | Hans Uszkoreit
Proceedings of the 17th Annual Conference of the European Association for Machine Translation

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Exploring cross-language statistical machine translation for closely related South Slavic languages
Maja Popović | Nikola Ljubešić
Proceedings of the EMNLP’2014 Workshop on Language Technology for Closely Related Languages and Language Variants

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Correlating decoding events with errors in Statistical Machine Translation
Eleftherios Avramidis | Maja Popović
Proceedings of the 11th International Conference on Natural Language Processing

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The tara corpus of human-annotated machine translations
Eleftherios Avramidis | Aljoscha Burchardt | Sabine Hunsicker | Maja Popović | Cindy Tscherwinka | David Vilar | Hans Uszkoreit
Proceedings of the Ninth International Conference on Language Resources and Evaluation (LREC'14)

Human translators are the key to evaluating machine translation (MT) quality and also to addressing the so far unanswered question when and how to use MT in professional translation workflows. This paper describes the corpus developed as a result of a detailed large scale human evaluation consisting of three tightly connected tasks: ranking, error classification and post-editing.

2013

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Selecting Feature Sets for Comparative and Time-Oriented Quality Estimation of Machine Translation Output
Eleftherios Avramidis | Maja Popović
Proceedings of the Eighth Workshop on Statistical Machine Translation

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A CCG-based Quality Estimation Metric for Statistical Machine Translation Learning from Human Judgments of Machine Translation Output
Maja Popovic | Eleftherios Avramidis | Aljoscha Burchardt | Sabine Hunsicker | Sven Schmeier | Cindy Tscherwinka | David Vilar
Proceedings of Machine Translation Summit XIV: Posters

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Learning from Human Judgments of Machine Translation Output
Maja Popovic | Eleftherios Avramidis | Aljoscha Burchardt | Sabine Hunsicker | Sven Schmeier | Cindy Tscherwinka | David Vilar
Proceedings of Machine Translation Summit XIV: Posters

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What can we learn about the selection mechanism for post-editing?
Maja Popović | Eleftherios Avramidis | Aljoscha Burchardt | David Vilar | Hans Uszkoreit
Proceedings of the 2nd Workshop on Post-editing Technology and Practice

2012

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TerrorCat: a Translation Error Categorization-based MT Quality Metric
Mark Fishel | Rico Sennrich | Maja Popović | Ondřej Bojar
Proceedings of the Seventh Workshop on Statistical Machine Translation

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Class error rates for evaluation of machine translation output
Maja Popović
Proceedings of the Seventh Workshop on Statistical Machine Translation

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Morpheme- and POS-based IBM1 and language model scores for translation quality estimation
Maja Popović
Proceedings of the Seventh Workshop on Statistical Machine Translation

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Involving Language Professionals in the Evaluation of Machine Translation
Eleftherios Avramidis | Aljoscha Burchardt | Christian Federmann | Maja Popović | Cindy Tscherwinka | David Vilar
Proceedings of the Eighth International Conference on Language Resources and Evaluation (LREC'12)

Significant breakthroughs in machine translation only seem possible if human translators are taken into the loop. While automatic evaluation and scoring mechanisms such as BLEU have enabled the fast development of systems, it is not clear how systems can meet real-world (quality) requirements in industrial translation scenarios today. The taraXÜ project paves the way for wide usage of hybrid machine translation outputs through various feedback loops in system development. In a consortium of research and industry partners, the project integrates human translators into the development process for rating and post-editing of machine translation outputs thus collecting feedback for possible improvements.

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Automatic MT Error Analysis: Hjerson Helping Addicter
Jan Berka | Ondřej Bojar | Mark Fishel | Maja Popović | Daniel Zeman
Proceedings of the Eighth International Conference on Language Resources and Evaluation (LREC'12)

We present a complex, open source tool for detailed machine translation error analysis providing the user with automatic error detection and classification, several monolingual alignment algorithms as well as with training and test corpus browsing. The tool is the result of a merge of automatic error detection and classification of Hjerson (Popović, 2011) and Addicter (Zeman et al., 2011) into the pipeline and web visualization of Addicter. It classifies errors into categories similar to those of Vilar et al. (2006), such as: morphological, reordering, missing words, extra words and lexical errors. The graphical user interface shows alignments in both training corpus and test data; the different classes of errors are colored. Also, the summary of errors can be displayed to provide an overall view of the MT system's weaknesses. The tool was developed in Linux, but it was tested on Windows too.

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Terra: a Collection of Translation Error-Annotated Corpora
Mark Fishel | Ondřej Bojar | Maja Popović
Proceedings of the Eighth International Conference on Language Resources and Evaluation (LREC'12)

Recently the first methods of automatic diagnostics of machine translation have emerged; since this area of research is relatively young, the efforts are not coordinated. We present a collection of translation error-annotated corpora, consisting of automatically produced translations and their detailed manual translation error analysis. Using the collected corpora we evaluate the available state-of-the-art methods of MT diagnostics and assess, how well the methods perform, how they compare to each other and whether they can be useful in practice.

2011

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DFKI’s SC and MT submissions to IWSLT 2011
David Vilar | Eleftherios Avramidis | Maja Popović | Sabine Hunsicker
Proceedings of the 8th International Workshop on Spoken Language Translation: Evaluation Campaign

We describe DFKI’s submission to the System Combination and Machine Translation tracks of the 2011 IWSLT Evaluation Campaign. We focus on a sentence selection mechanism which chooses the (hopefully) best sentence among a set of candidates. The rationale behind it is to take advantage of the strengths of each system, especially given an heterogeneous dataset like the one in this evaluation campaign, composed of TED Talks of very different topics. We focus on using features that correlate well with human judgement and, while our primary system still focus on optimizing the BLEU score on the development set, our goal is to move towards optimizing directly the correlation with human judgement. This kind of system is still under development and was used as a secondary submission.

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Towards Automatic Error Analysis of Machine Translation Output
Maja Popović | Hermann Ney
Computational Linguistics, Volume 37, Issue 4 - December 2011

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Evaluate with Confidence Estimation: Machine ranking of translation outputs using grammatical features
Eleftherios Avramidis | Maja Popovic | David Vilar | Aljoscha Burchardt
Proceedings of the Sixth Workshop on Statistical Machine Translation

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Evaluation without references: IBM1 scores as evaluation metrics
Maja Popović | David Vilar | Eleftherios Avramidis | Aljoscha Burchardt
Proceedings of the Sixth Workshop on Statistical Machine Translation

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Morphemes and POS tags for n-gram based evaluation metrics
Maja Popović
Proceedings of the Sixth Workshop on Statistical Machine Translation

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From Human to Automatic Error Classification for Machine Translation Output
Maja Popović | Aljoscha Burchardt
Proceedings of the 15th Annual Conference of the European Association for Machine Translation

2009

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Syntax-Oriented Evaluation Measures for Machine Translation Output
Maja Popović | Hermann Ney
Proceedings of the Fourth Workshop on Statistical Machine Translation

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The RWTH Machine Translation System for WMT 2009
Maja Popović | David Vilar | Daniel Stein | Evgeny Matusov | Hermann Ney
Proceedings of the Fourth Workshop on Statistical Machine Translation

2007

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Word Error Rates: Decomposition over POS classes and Applications for Error Analysis
Maja Popović | Hermann Ney
Proceedings of the Second Workshop on Statistical Machine Translation

2006

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Morpho-syntactic Information for Automatic Error Analysis of Statistical Machine Translation Output
Maja Popović | Adrià de Gispert | Deepa Gupta | Patrik Lambert | Hermann Ney | José B. Mariño | Marcello Federico | Rafael Banchs
Proceedings on the Workshop on Statistical Machine Translation

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POS-based Word Reorderings for Statistical Machine Translation
Maja Popović | Hermann Ney
Proceedings of the Fifth International Conference on Language Resources and Evaluation (LREC’06)

Translation In this work we investigate new possibilities for improving the quality of statistical machine translation (SMT) by applying word reorderings of the source language sentences based on Part-of-Speech tags. Results are presented on the European Parliament corpus containing about 700k sentences and 15M running words. In order to investigate sparse training data scenarios, we also report results obtained on about 1\% of the original corpus. The source languages are Spanish and English and target languages are Spanish, English and German. We propose two types of reorderings depending on the language pair and the translation direction: local reorderings of nouns and adjectives for translation from and into Spanish and long-range reorderings of verbs for translation into German. For our best translation system, we achieve up to 2\% relative reduction of WER and up to 7\% relative increase of BLEU score. Improvements can be seen both on the reordered sentences as well as on the rest of the test corpus. Local reorderings are especially important for the translation systems trained on the small corpus whereas long-range reorderings are more effective for the larger corpus.

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AER: do we need to “improve” our alignments?
David Vilar | Maja Popovic | Hermann Ney
Proceedings of the Third International Workshop on Spoken Language Translation: Papers

2005

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Augmenting a Small Parallel Text with Morpho-Syntactic Language
Maja Popović | David Vilar | Hermann Ney | Slobodan Jovičić | Zoran Šarić
Proceedings of the ACL Workshop on Building and Using Parallel Texts

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Exploiting phrasal lexica and additional morpho-syntactic language resources for statistical machine translation with scarce training data
Maja Popovic | Hermann Ney
Proceedings of the 10th EAMT Conference: Practical applications of machine translation

2004

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Towards the Use of Word Stems and Suffixes for Statistical Machine Translation
Maja Popović | Hermann Ney
Proceedings of the Fourth International Conference on Language Resources and Evaluation (LREC’04)

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Statistical machine translation of spontaneous speech with scarce resources
Evgeny Matusov | Maja Popovic | Richard Zens | Hermann Ney
Proceedings of the First International Workshop on Spoken Language Translation: Papers

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Improving Word Alignment Quality using Morpho-syntactic Information
Hermann Ney | Maja Popovic
COLING 2004: Proceedings of the 20th International Conference on Computational Linguistics

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Error Measures and Bayes Decision Rules Revisited with Applications to POS Tagging
Hermann Ney | Maja Popović | David Sündermann
Proceedings of the 2004 Conference on Empirical Methods in Natural Language Processing

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