David Alfter


2022

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Proceedings of the 11th Workshop on NLP for Computer Assisted Language Learning
David Alfter | Elena Volodina | Thomas François | Piet Desmet | Frederik Cornillie | Arne Jönsson | Evelina Rennes
Proceedings of the 11th Workshop on NLP for Computer Assisted Language Learning

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Towards a Verb Profile: distribution of verbal tenses in FFL textbooks and in learner productions
Nami Yamaguchi | David Alfter | Kaori Sugiyama | Thomas François
Proceedings of the 11th Workshop on NLP for Computer Assisted Language Learning

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L’Attention est-elle de l’Explication ? Une Introduction au Débat (Is Attention Explanation ? An Introduction to the Debate )
Adrien Bibal | Remi Cardon | David Alfter | Rodrigo Wilkens | Xiaoou Wang | Thomas François | Patrick Watrin
Actes de la 29e Conférence sur le Traitement Automatique des Langues Naturelles. Volume 1 : conférence principale

Nous présentons un résumé en français et un résumé en anglais de l’article Is Attention Explanation ? An Introduction to the Debate (Bibal et al., 2022), publié dans les actes de la conférence 60th Annual Meeting of the Association for Computational Linguistics (ACL 2022).

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FABRA: French Aggregator-Based Readability Assessment toolkit
Rodrigo Wilkens | David Alfter | Xiaoou Wang | Alice Pintard | Anaïs Tack | Kevin P. Yancey | Thomas François
Proceedings of the Thirteenth Language Resources and Evaluation Conference

In this paper, we present the FABRA: readability toolkit based on the aggregation of a large number of readability predictor variables. The toolkit is implemented as a service-oriented architecture, which obviates the need for installation, and simplifies its integration into other projects. We also perform a set of experiments to show which features are most predictive on two different corpora, and how the use of aggregators improves performance over standard feature-based readability prediction. Our experiments show that, for the explored corpora, the most important predictors for native texts are measures of lexical diversity, dependency counts and text coherence, while the most important predictors for foreign texts are syntactic variables illustrating language development, as well as features linked to lexical sophistication. FABRA: have the potential to support new research on readability assessment for French.

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Proceedings of the 2nd Workshop on Tools and Resources to Empower People with REAding DIfficulties (READI) within the 13th Language Resources and Evaluation Conference
Rodrigo Wilkens | David Alfter | Rémi Cardon | Núria Gala
Proceedings of the 2nd Workshop on Tools and Resources to Empower People with REAding DIfficulties (READI) within the 13th Language Resources and Evaluation Conference

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A Dictionary-Based Study of Word Sense Difficulty
David Alfter | Rémi Cardon | Thomas François
Proceedings of the 2nd Workshop on Tools and Resources to Empower People with REAding DIfficulties (READI) within the 13th Language Resources and Evaluation Conference

In this article, we present an exploratory study on perceived word sense difficulty by native and non-native speakers of French. We use a graded lexicon in conjunction with the French Wiktionary to generate tasks in bundles of four items. Annotators manually rate the difficulty of the word senses based on their usage in a sentence by selecting the easiest and the most difficult word sense out of four. Our results show that the native and non-native speakers largely agree when it comes to the difficulty of words. Further, the rankings derived from the manual annotation broadly follow the levels of the words in the graded resource, although these levels were not overtly available to annotators. Using clustering, we investigate whether there is a link between the complexity of a definition and the difficulty of the associated word sense. However, results were inconclusive. The annotated data set is available for research purposes.

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CENTAL at TSAR-2022 Shared Task: How Does Context Impact BERT-Generated Substitutions for Lexical Simplification?
Rodrigo Wilkens | David Alfter | Rémi Cardon | Isabelle Gribomont | Adrien Bibal | Watrin Patrick | Marie-Catherine De marneffe | Thomas François
Proceedings of the Workshop on Text Simplification, Accessibility, and Readability (TSAR-2022)

Lexical simplification is the task of substituting a difficult word with a simpler equivalent for a target audience. This is currently commonly done by modeling lexical complexity on a continuous scale to identify simpler alternatives to difficult words. In the TSAR shared task, the organizers call for systems capable of generating substitutions in a zero-shot-task context, for English, Spanish and Portuguese. In this paper, we present the solution we (the {textsc{cental} team) proposed for the task. We explore the ability of BERT-like models to generate substitution words by masking the difficult word. To do so, we investigate various context enhancement strategies, that we combined into an ensemble method. We also explore different substitution ranking methods. We report on a post-submission analysis of the results and present our insights for potential improvements. The code for all our experiments is available at https://gitlab.com/Cental-FR/cental-tsar2022.

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Is Attention Explanation? An Introduction to the Debate
Adrien Bibal | Rémi Cardon | David Alfter | Rodrigo Wilkens | Xiaoou Wang | Thomas François | Patrick Watrin
Proceedings of the 60th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)

The performance of deep learning models in NLP and other fields of machine learning has led to a rise in their popularity, and so the need for explanations of these models becomes paramount. Attention has been seen as a solution to increase performance, while providing some explanations. However, a debate has started to cast doubt on the explanatory power of attention in neural networks. Although the debate has created a vast literature thanks to contributions from various areas, the lack of communication is becoming more and more tangible. In this paper, we provide a clear overview of the insights on the debate by critically confronting works from these different areas. This holistic vision can be of great interest for future works in all the communities concerned by this debate. We sum up the main challenges spotted in these areas, and we conclude by discussing the most promising future avenues on attention as an explanation.

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Linguistic Corpus Annotation for Automatic Text Simplification Evaluation
Rémi Cardon | Adrien Bibal | Rodrigo Wilkens | David Alfter | Magali Norré | Adeline Müller | Watrin Patrick | Thomas François
Proceedings of the 2022 Conference on Empirical Methods in Natural Language Processing

Evaluating automatic text simplification (ATS) systems is a difficult task that is either performed by automatic metrics or user-based evaluations. However, from a linguistic point-of-view, it is not always clear on what bases these evaluations operate. In this paper, we propose annotations of the ASSET corpus that can be used to shed more light on ATS evaluation. In addition to contributing with this resource, we show how it can be used to analyze SARI’s behavior and to re-evaluate existing ATS systems. We present our insights as a step to improve ATS evaluation protocols in the future.

2021

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Proceedings of the 10th Workshop on NLP for Computer Assisted Language Learning
David Alfter | Elena Volodina | Ildikó Pilan | Johannes Graën | Lars Borin
Proceedings of the 10th Workshop on NLP for Computer Assisted Language Learning

2020

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Using Multilingual Resources to Evaluate CEFRLex for Learner Applications
Johannes Graën | David Alfter | Gerold Schneider
Proceedings of the Twelfth Language Resources and Evaluation Conference

The Common European Framework of Reference for Languages (CEFR) defines six levels of learner proficiency, and links them to particular communicative abilities. The CEFRLex project aims at compiling lexical resources that link single words and multi-word expressions to particular CEFR levels. The resources are thought to reflect second language learner needs as they are compiled from CEFR-graded textbooks and other learner-directed texts. In this work, we investigate the applicability of CEFRLex resources for building language learning applications. Our main concerns were that vocabulary in language learning materials might be sparse, i.e. that not all vocabulary items that belong to a particular level would also occur in materials for that level, and, on the other hand, that vocabulary items might be used on lower-level materials if required by the topic (e.g. with a simpler paraphrasing or translation). Our results indicate that the English CEFRLex resource is in accordance with external resources that we jointly employ as gold standard. Together with other values obtained from monolingual and parallel corpora, we can indicate which entries need to be adjusted to obtain values that are even more in line with this gold standard. We expect that this finding also holds for the other languages

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Proceedings of the 9th Workshop on NLP for Computer Assisted Language Learning
David Alfter | Elena Volodina | Ildikó Pilan | Herbert Lange | Lars Borin
Proceedings of the 9th Workshop on NLP for Computer Assisted Language Learning

2019

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Interconnecting lexical resources and word alignment: How do learners get on with particle verbs?
David Alfter | Johannes Graën
Proceedings of the 22nd Nordic Conference on Computational Linguistics

In this paper, we present a prototype for an online exercise aimed at learners of English and Swedish that serves multiple purposes. The exercise allows learners of the aforementioned languages to train their knowledge of particle verbs receiving clues from the exercise application. The user themselves decide which clue to receive and pay in virtual currency for each, which provides us with valuable information about the utility of the clues that we provide as well as the learners willingness to trade virtual currency versus accuracy of their choice. As resources, we use list with annotated levels from the proficiency scale defined by the Common European Framework of Reference (CEFR) and a multilingual corpus with syntactic dependency relations and word annotation for all language pairs. From the latter resource, we extract translation equivalents for particle verb construction together with a list of parallel corpus examples that can be used as clues in the exercise.

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LEGATO: A flexible lexicographic annotation tool
David Alfter | Therese Lindström Tiedemann | Elena Volodina
Proceedings of the 22nd Nordic Conference on Computational Linguistics

This article is a report from an ongoing project aiming at analyzing lexical and grammatical competences of Swedish as a Second language (L2). To facilitate lexical analysis, we need access to metalinguistic information about relevant vocabulary that L2 learners can use and understand. The focus of the current article is on the lexical annotation of the vocabulary scope for a range of lexicographical aspects, such as morphological analysis, valency, types of multi-word units, etc. We perform parts of the analysis automatically, and other parts manually. The rationale behind this is that where there is no possibility to add information automatically, manual effort needs to be added. To facilitate the latter, a tool LEGATO has been designed, implemented and currently put to active testing.

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Proceedings of the 8th Workshop on NLP for Computer Assisted Language Learning
David Alfter | Elena Volodina | Lars Borin | Ildikó Pilan | Herbert Lange
Proceedings of the 8th Workshop on NLP for Computer Assisted Language Learning

2018

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Towards Single Word Lexical Complexity Prediction
David Alfter | Elena Volodina
Proceedings of the Thirteenth Workshop on Innovative Use of NLP for Building Educational Applications

In this paper we present work-in-progress where we investigate the usefulness of previously created word lists to the task of single-word lexical complexity analysis and prediction of the complexity level for learners of Swedish as a second language. The word lists used map each word to a single CEFR level, and the task consists of predicting CEFR levels for unseen words. In contrast to previous work on word-level lexical complexity, we experiment with topics as additional features and show that linking words to topics significantly increases accuracy of classification.

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SB@GU at the Complex Word Identification 2018 Shared Task
David Alfter | Ildikó Pilán
Proceedings of the Thirteenth Workshop on Innovative Use of NLP for Building Educational Applications

In this paper, we describe our experiments for the Shared Task on Complex Word Identification (CWI) 2018 (Yimam et al., 2018), hosted by the 13th Workshop on Innovative Use of NLP for Building Educational Applications (BEA) at NAACL 2018. Our system for English builds on previous work for Swedish concerning the classification of words into proficiency levels. We investigate different features for English and compare their usefulness using feature selection methods. For the German, Spanish and French data we use simple systems based on character n-gram models and show that sometimes simple models achieve comparable results to fully feature-engineered systems.

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Proceedings of the 7th workshop on NLP for Computer Assisted Language Learning
Ildikó Pilán | Elena Volodina | David Alfter | Lars Borin
Proceedings of the 7th workshop on NLP for Computer Assisted Language Learning

2016

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Coursebook Texts as a Helping Hand for Classifying Linguistic Complexity in Language Learners’ Writings
Ildikó Pilán | David Alfter | Elena Volodina
Proceedings of the Workshop on Computational Linguistics for Linguistic Complexity (CL4LC)

We bring together knowledge from two different types of language learning data, texts learners read and texts they write, to improve linguistic complexity classification in the latter. Linguistic complexity in the foreign and second language learning context can be expressed in terms of proficiency levels. We show that incorporating features capturing lexical complexity information from reading passages can boost significantly the machine learning based classification of learner-written texts into proficiency levels. With an F1 score of .8 our system rivals state-of-the-art results reported for other languages for this task. Finally, we present a freely available web-based tool for proficiency level classification and lexical complexity visualization for both learner writings and reading texts.

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From distributions to labels: A lexical proficiency analysis using learner corpora
David Alfter | Yuri Bizzoni | Anders Agebjörn | Elena Volodina | Ildikó Pilán
Proceedings of the joint workshop on NLP for Computer Assisted Language Learning and NLP for Language Acquisition

2014

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A Dictionary Data Processing Environment and Its Application in Algorithmic Processing of Pali Dictionary Data for Future NLP Tasks
Jürgen Knauth | David Alfter
Proceedings of the Fifth Workshop on South and Southeast Asian Natural Language Processing